AOH :: CSHP48_3.FAQ
HP 48 S/SX/G/GX Frequently Asked Questions
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From: madd0118@gmi.edu (Keith Maddock)
Newsgroups: comp.sys.hp48,comp.answers,news.answers
Subject: comp.sys.hp48 FAQ : 3 of 4 : Appendices
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Summary: Answers to Frequently Asked Questions about HP48 calculators
Keywords: FAQ, HP48
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Last-modified: 06/20/1995
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*********************************************************
HP 48 S/SX/G/GX Frequently Asked Questions List
*********************************************************
PART 3 of 4: Appendices A - H
Currently Maintained by: Keith Maddock (madd0118@nova.gmi.edu)
Originally Compiled by: Darryl Okahata
Key: ! =new Q/A + =revised answer
PART 3:
* Appendix A: ASC\-> and \->ASC functions:
* Appendix B: Using non-HP RAM cards in your HP 48SX:
* Appendix C: What's new in the HP 48G/GX
* Appendix D: The EquationWriter Bug & Rev J Bugfix
* Appendix E: Compact Data Storage:
* Appendix F: Various useful functions
* Appendix G: Rotation rate to angular frequency conversion bug
* Appendix H: How to make a Serial Cable for your HP48
******************************************************************
* Appendix A: ASC\-> and \->ASC functions:
Note: Since this appendix was written by Bill, I dare not modify it.
However, I wish to note that ASC\-> and \-ASC do work on both the SX and
GX versions.
From: billw@hpcvra.CV.HP.COM (William C Wickes)
ASCII Encoding HP 48SX Objects
Sending an HP 48SX object via electronic mail can be difficult if the
object does not have an ASCII form, such as is the case for library
objects. There are various encoding schemes available on different
computer systems, but these require that the sender and receiver have
similar computers, or at least compatible encode/decode schemes. The
programs listed below perform the encoding and decoding on the HP 48SX itself,
which has the advantage of being completely independent of any computer.
The programs are nominally called \->ASC and ASC\->. The former takes an
object from the stack and converts it to a string, in which each nibble of the
object and its checksum is converted to a character 0-9 or A-F. (The object
must be in RAM, otherwise a "ROM Object" error is returned.) For sake of easy
inclusion in email letters, the string is broken up by linefeed characters
after every 64 characters.
ASC\-> is the inverse of \->ASC: it takes a string created by \->ASC and
converts it back into an object. When you transmit the encoded strings,
be sure not to change the string; ASC\-> uses the checksum encoded in the
string to verify that the decoding is correct. An "Invalid String" error
is returned if the result object does not match the original object
encoded by \->ASC. When you upload a string to your computer, use HP 48
translate mode 3 so that the HP 48 will convert any CR/LF's back to LF's
when the string is later downloaded.
Two versions of ASC\-> are included here. The first (P1) is in HP 48 user
language, using SYSEVALs to execute system objects. P2 is a
string that the setup program uses P1 to decode into an executable
ASC\->--then P1 is discarded. The second version is more
compact than the first, and also uneditable and therefore safer (but it can't
be transmitted in ASCII form, which helps to make the point of this exercise).
Here are the programs, contained in a directory:
(start)
%%HP: T(3)A(D)F(.);
DIR
P1 @ ASC\-> Version 1.
\<<
IF DUP TYPE 2 \=/
THEN "Not A String" DOERR
END RCWS \-> ws
\<< 16 STWS
#0 NEWOB SWAP DUP SIZE
IF DUP 4 <
THEN DROP SWAP DROP "Invalid String" DOERR
END
DUP 65 / IP - 4 - # 18CEAh SYSEVAL
"" OVER # 61C1Ch SYSEVAL
SWAP # 6641F8000AF02DCCh
# 130480679BF8CC0h # 518Ah SYSEVAL
# 19610313418D7EA4h # 518Ah SYSEVAL
# 7134147114103123h # 518Ah SYSEVAL
# 5F6A971131607414h # 518Ah SYSEVAL
# 12EA1717EA3F130Ch # 518Ah SYSEVAL
# 280826B3012808F4h # 518Ah SYSEVAL
# 6B7028080BEE9091h # 518Ah SYSEVAL
# BE5DC1710610C512h # 518Ah SYSEVAL
# 705D00003431A078h # 518Ah SYSEVAL
# 3D8FA26058961431h # 518Ah SYSEVAL
# 312B0514h # 518Ah SYSEVAL
# 18F23h SYSEVAL
DUP BYTES DROP 4 ROLL
IF ==
THEN SWAP DROP
ELSE DROP "Invalid String" DOERR
END ws STWS
\>>
\>>
P2 @ ASC\-> Version 2. To be converted by ASC\-> version 1.
"D9D20D29512BF81D0040D9D20E4A209000000007566074726636508813011920
140007FE30B9F060ED3071040CA1304EC3039916D9D2085230B9F06C2A201200
094E66716C696460235472796E676933A1B21300ED30FD5502C230C1C1632230
CCD20FA0008F14660CC8FB97608403104AE7D814313016913213014117414317
414706131179A6F5C031F3AE7171AE214F8082103B6280821909EEB0808207B6
215C0160171CD5EB870A13430000D50713416985062AF8D341508813044950B9
F06BBF06EFC36B9F0644230C2A201200094E66716C696460235472796E676933
A1B2130B21300373"
P3 @\->ASC. To be converted by ASC\->.
"D9D20D2951881304495032230FD5502C230A752688130ADB467FE30322306AC3
0CB916E0E30CBD30F6E30C1C1632230CCD20DC0008F14660CC8FB97608403104
AE7D8143130169174147061741431311534AC6B4415141534946908D9B026155
4A6F53131F3AE731A014C161AE215F08082103A6280821939EEC08082170A621
4C161170CD56B870A18503430000D5071351796A9F8D2D02639916D9D2085230
C2A209100025F4D402F426A6563647933A1B2130A2116B213033C0"
SETUP @Automatic setup program
\<< P2 P1 'ASC\->' STO
P3 ASC\-> '\->ASC' STO
{ P1 P2 P3 SETUP } PURGE
\>>
END
(end)
Installation instructions:
1. Edit the above text between (start) and (end) into a text file
named CONV (for example). Be sure that you leave the strings
exactly as entered above, with no extra spaces or other
invisible characters at the beginnings or ends of the lines.
2. Set the HP 48SX into ASCII transfer mode.
3. Using Kermit, download CONV text file to the 48, verify its
checksum (6C8Ah).
4. Execute CONV to make it the current directory.
5. Execute SETUP.
6. The directory CONV now contains ASC\-> and \->ASC, ready to
use.
To archive the decoded versions of ASC\-> and \->ASC back on your computer,
be sure to set the HP 48SX in binary transfer mode before uploading.
Disclaimers:
+ Use the programs at your own risk. Any time you delve into the SYSEVAL
world, there are increased dangers. Archive your 48 memory before
experimenting with these programs! Also, verify the checksums of objects
defined above to make sure they have been downloaded correctly, before
executing ASC\->.
+ I will not answer questions about how the programs work. This is not
because of any great secrecy, but rather because it's hard to give
any answer that doesn't lead to more questions, and more, and more...
+ 48 hackers are welcome to mine any nuggets they can from the programs,
and from the fact that \->ASC is a convenient way to decompile an object.
******************************************************************
* Appendix B: Using non-HP RAM cards in your HP 48SX:
If you use RAM cards that are NOT designed for the HP 48SX, it is
possible to severely damage your HP 48SX. If you want to be safe, you
should only use RAM cards designed for the HP 48SX.
Here is an edited discussion from comp.sys.handhelds.
From steveh@hpcvra.CV.HP.COM Fri Mar 1 17:00:00 1991
From: steveh@hpcvra.CV.HP.COM (Steve Harper)
Date: Thu, 10 May 1990 22:46:09 GMT
Subject: RE: HP48SX Memory Card Pricing
Organization: Hewlett-Packard Co., Corvallis, OR, USA
There has been a substantial amount of comment regarding the
memory cards for the HP48SX and their prices. My purpose in this
response is not to attempt to justify any particular price, but
rather to present the technical reasons why there is a
substantial price difference between the memory cards and other
types of expansion memory for PC's, for example, with which users
are probably more familiar.
Some users have correctly pointed out that the memory in the
cards is static RAM rather than dynamic RAM commonly used in
PC's. Dynamic RAM uses one transistor and a capacitor for each
bit of memory whereas static RAM requires either four transistors
and two resistors, or six transistors. The net result is that an
equivalent amount of static RAM is much larger and therefore much
more expensive than dynamic RAM. The advantage is that static
RAM doesn't need to continually be running and drawing current
(refresh cycles) to retain the contents of memory.
In addition, the static memory used in the cards is not just any
static memory, but is specially processed and/or selected for
very low standby current. This allows the backup battery in the
card to keep memory alive for a very long time, rather than
requiring the user to replace it every few months. The special
processing and/or special testing to select low current parts
adds to the already higher cost of the static RAM chips.
The standard molded plastic DIP package used for most integrated
circuits, including memory chips, is relatively inexpensive
because of its simplicity and the huge volumes. Unfortunately,
these packages are too large to put into a memory card.
Therefore, the card manufacturer mounts the individual silicon
memory chips directly on a special thin PC board together with
the memory support chips. Because multiple chips are being
placed in a single hybrid package in a special process which has
lower volume, yields are lower and this again causes the cost to
be higher. Indeed, the yield becomes exponentially worse as the
number of chips and interconnections increases in such a
packaging process.
In addition to the memory chips themselves, two more integrated
circuits and several discrete components are required for power
and logic control. A bipolar technology chip senses the external
voltage and switches the power to the chips from the internal
keep-alive battery as needed. A CMOS gate array chip protects
the memory address and data lines from glitches/ESD when the card
is not plugged in. This chip also generates the proper enabling
signals when there are multiple memory chips in the card, as is
presently the case with the 128 Kbyte RAM card. These chips must
be designed for extremely low current, just as the memory chips
are.
In addition to the battery and the battery holder, the other
mechanical parts are important, too. The molded plastic frame
holds the PC board and provides the foundation for the metal
overlays and the shutter-and-springs assembly which protects the
contacts from ESD and from contaminants. The write-protect
switch is also an important feature. It is quite expensive for
the manufacturer to make the tools necessary to fabricate each of
these parts as well as the tools to assemble and test the
complete card. While the volume of memory cards is relatively
low this tooling cost represents a significant part of the cost
of each card.
Admittedly, there are other alternatives, such as those presently
used in PC's, to provide a memory expansion capability. To
provide that kind of expansion would require the calculator to be
much larger than it is and possibly more expensive. This is
clearly very undesirable.
Other features that were felt to be essential were the ability to
distribute software applications and to share and archive/backup
user-created programs and data. Other expansion alternatives do
not provide these important benefits. The IO capabilities of the
calculator provide these features only to a limited degree.
One other item bears repeating here: Memory cards for use in the
calculator will clearly indicate that they are for use with the
HP48SX. Other memory cards exist which are mechanically
compatible with the HP48S, but these cards cannot be relied upon
to work electrically in the calculator. The HP48SX cards are
designed for a lower supply voltage range. Use of the other
cards may cause memory loss, and under certain circumstances may
even damage your calculator electrically.
From steveh@hpcvra.CV.HP.COM Fri Mar 1 17:00:00 1991
From: steveh@hpcvra.CV.HP.COM (Steve Harper)
Date: Fri, 11 May 1990 16:52:07 GMT
Subject: Re: Memory Card: Give Us *True* Facts!
Organization: Hewlett-Packard Co., Corvallis, OR, USA
My previous statement that under certain circumstances the
calculator may even be damaged electrically is not a ploy.
If the calculator's internal power supply voltage happens to
be near the low end of the range, say 4.1 V, and the voltage
at which the card's voltage control chip shuts it down
happens to be near the high end of its range, say 4.2 V (this
can and does occasionally occur for the non-HP48SX cards),
then the calculator will start to drive the memory address
lines and the card will still have these clamped to ground
(that's what it does to protect itself when there is not
sufficient system voltage to run). This unfortunate situation
may simply trash your memory, or if the calculator tries
to drive enough of the lines high at the same time, several
hundred milliamps may flow...for awhile that is, until something
gives up... On the other hand, your calculator and a particular
non-HP48SX card may work just fine if those voltages happen
to be at the other end of their ranges. These voltages are
also slightly temperature sensitive. It may work in the
classroom or office and not at the beach, or vice versa.
The voltage trip point of the HP48SX cards has been set
lower (a different voltage control chip) so that this cannot
occur, regardless of part and temperature variations.
One other item was brought to my attention yesterday by
Preston Brown that I should have included in my original
posting here. While most of us recognize that comparing
ram cards to a handful of dynamic ram chips to plug into
your PC is apples and oranges, it may be more interesting
to compare the HP48SX cards with cards for other products,
like the Atari Portfolio, the Poquet, the NEC Ultralite,
etc. I believe you will find that the prices on the
HP48SX cards are not at all out of line.
Steve
"I claim all disclaimers..."
the non-HP48SX cards
From prestonb@hpcvra.CV.HP.COM Fri Mar 1 17:00:00 1991
From: prestonb@hpcvra.CV.HP.COM (Preston Brown)
Date: Thu, 17 May 1990 17:26:53 GMT
Subject: Re: Memory Card: Give Us *True* Facts!
Organization: Hewlett-Packard Co., Corvallis, OR, USA
When the RAM cards detect that voltage is to low to operate they
clamp the address lines to ground. This clamping is done by turning
on the output drivers of a custom chip included on the card. The
clamping current is speced at 2mA min at the Vol output level. Since
the 48 can be trying to drive the line all the way high even more
current is typical. 10mA per fight is not uncommon with totals of
several hundred mAs.
The VDD power supply is regulated at 4.1 - 4.9 with typical
parts at the low end (4.3). The power to the cards is switched
thru a transistor, creating up to a 0.1V drop. Standard Epson
cards have a significant chance of seeing this voltage as
to low and shutting down. We have seen cards do this in the lab.
When it occurs the calculator locks up with VDD pulled down
to about 2.5V and 250mA being drawn from the batteries. This
current drain greatly exceeds the ratings for the power supply
and can damage your calc. The least that will happen is a loss
of memory.
Now, why didn't we regulate VDD higher?
The 48 has two power supplies VDD at 4.3 and VH at 8.5. VH
cannot be regulated higher without exceeding the spec for
our CMOS IC process. VH is used as the + voltage for the I/O.
In order to meet a +3V output level VH must be more then 3.6V
above VDD. (VDD is used as I/O ground). Our power supply
system increase the battery life and reduces the cost greatly
for the wired I/O.
Preston
******************************************************************
* Appendix C: What's new in the HP 48G/GX?
[ The following was taken from a posting by Joe Horn. ]
+--------------------+
| WHAT'S NEW |
| IN THE HP48 G/GX |
+--------------------+
collected & annotated
by Joseph K. Horn
(1) AUTOMATIC LIST PROCESSING
Almost all commands that did not accept list(s) as their arguments
can do so now. Here are just a few examples:
{ 1 2 3 } SF sets flags 1, 2, and 3
{ 1 2 3 } SQ --> { 1 4 9 }
{ 2 4 } 10 / --> { .2 .4 }
10 { 2 4 } / --> { 5 2.5 }
{ 10 12 } { 2 4 } / --> { 5 3 }
{ .1 .2 .5 } ->Q --> { '1/10' '1/5' '1/2' }
{ freq freq ...} { dur dur ... } BEEP can play a song with no
audible hiccup between tones.
Since + has always been used to concatenate lists, a new ADD
function exists to add the elements of two lists, like this:
{ 1 2 3 } { 4 5 6 } ADD returns { 5 7 9 }, whereas
{ 1 2 3 } { 4 5 6 } + returns { 1 2 3 4 5 6 } as it did
before.
The only commands which do not have automatic list processing are:
a. those which never get a Bad Argument Type error (like DUP),
b. meta-object commands (like ROLL),
c. program branch structures (like FOR), and
d. commands that specifically work on lists (like GET).
Sometimes the results are non-obvious, for example:
5 { A B C } STO --> A=5, B=5, C=5
{ 5 6 7 } 'A' STO --> A={ 5 6 7 } (same as on SX)
{ 5 6 7 } { A B C } STO --> A=5, B=6, C=7
List processing is only recursive for ->Q and ->Qpi.
(2) PORTS AND MEMORY
The HP48G, like the 48S, only has 32K RAM. The GX, unlike the SX,
has 128K RAM built-in. Card slot 1 can contain another 128K
(maximum), but card slot 2 can contain up to 4 megabytes of RAM.
Only port 1 can be merged in the GX. Card slot 2, which is
intended for large-capacity RAM cards, is permanently "free", and
is automatically divided up into 128K "ports", each of which
becomes Port 2, Port 3, Port 4, etc. Up to 4 Megabytes can be
plugged into slot 2, which would then become Port 2 through Port
33. (Although the FREE and MERGE commands were kept for HP 48SX
compatibility, GX users will prefer the new FREE1 and MERGE1
commands). Therefore the maximum amount of merged main memory is
256K (unlike the SX which allowed up to 288K) after MERGE1; the
maximum amount of fully online free independent memory is 4224K
after FREE1.
(3) LOCAL VARIABLES.
Variable names prefixed with a <- (backarrow character) are
compiled as local (temporary) variable name objects even if
they're not explicitly after FOR or ->. This allows programs to
share values through local variables, which is much faster than
sharing values through global variables, and they get purged
automatically.
(4) SPEED.
CPU clock speed is double the S/SX's, but throughput is estimated
to be only 40% faster, primarily due to the fact that *all* RAM &
ROM is now bankswitched (on the S/SX only a 32K portion of the ROM
required bank switching), and it still has the same 4-bit bus
bottleneck.
(5) IMPROVED COMMANDS:
AXES can now also specify the spacing of the tick marks.
DEPND can now also specify the initial values and tolerance
for the new DIFFEQ plot type.
REPL and SUB now work on arrays.
(6) HP SOLVE EQUATION LIBRARY CARD COMMANDS:
AMORT, amortization calculations
CONLIB, starts Constants Library catalog
CONST, returns value of a named CONLIB constant
DARCY, calculates Darcy friction factor
EQNLIB, starts Equation Library catalog
F0lambda, calculates black-body power fraction
FANNING, calculates Fanning friction factor
LIBEVAL is a generalized form of the EQ card's ELSYSEVAL; it
executes any XLIB by its library number
MCALC, marks an MSOLVR variable as "not user-defined"
MINEHUNT, starts the "Minehunt" video game
MINIT, initializes Mpar from 'EQ' for MSOLVR
MITM, customizes title & menu of MSOLVR's screen
MROOT, solve for variable(s) in MSOLVR
MSOLVR, shows Multiple Equation Solver menu
MUSER, marks an MSOLVR variable as "user-defined"
SIDENS, density of silicon as function of temperature
SOLVEQN, starts solver for specified EqLib equation(s)
TDELTA, subtracts temperatures like "-" ought to but doesn't
TINC, adds temperatures like "+" ought to but doesn't
TVM, shows the financial calculator (Time Value of Money) menu
TVMBEG, sets payments-at-beginning-of-periods mode
TVMEND, sets payments-at-end-of-periods mode
TVMROOT, solves for a TVM variable
ZFACTOR, calculates gas compressibility factor Z
Note: The EQ Card's Periodic Table and Tetris game are not in the
HP 48G/GX, but the EQ Card can be used in the GX if those
applications are needed. Tetris was not included because no
agreement on royalty was reached. The Periodic Table is
available separately as freeware on HPCVBBS.
(7) NEW ARRAY COMMANDS:
COL+, inserts a column vector into a matrix or a number into a
vector (like INSCOL/PUTCOL in Donnelly's Tool Library)
COL-, deletes a column from a matrix or number from a vector
(identical to DELCOL in Donnelly's Tool Library)
COL->, combines multiple column vectors into a matrix
->COL, breaks a matrix into multiple column vectors
(like repeated GETCOL in Donnelly's Tool Library)
COND, column norm condition number of a square matrix
CSWP, swaps two columns in a matrix
(like EXCOL in Donnelly's Tool Library)
->DIAG, returns vector of major diagonal elements of a matrix
DIAG->, creates matrix with specified diagonal elements
EGV, eigenvalues and right eigenvectors of a square matrix
EGVL, eigenvalues of a square matrix
FFT, discrete Fourier transform
IFFT, inverse discrete Fourier transform
LQ, returns the LQ factorization of a matrix
LSQ, minimum norm least-squares solution to an ill-determined
system of linear equations
LU, returns the Crout LU decomposition of a square matrix
PCOEF, returns polynomial with given roots (inverse of PROOT)
PEVAL, evaluates polynomial at x
PROOT, finds all roots of polynomial (inverse of PCOEF)
QR, returns QR factorization of a matrix
RANK, rank of a rectangular matrix (uses flag -54)
RANM, creates matrix with random elements
RCI, multiplies elements in one row of a matrix by a scalar
RCIJ, does RCI then adds the result to a row
ROW+, inserts a row vector into a matrix or a number into a vector
(like INSROW/PUTROW in Donnelly's Tool Library)
ROW-, deletes a row from a matrix or number from a vector
(identical to DELROW in Donnelly's Tool Library)
ROW->, combines multiple row vectors into a matrix
->ROW, breaks a matrix into multiple row vectors
(like repeated GETROW in Donnelly's Tool Library)
RSWP, swaps two rows in a matrix
(identical to EXROW in Donnelly's Tool Library)
SCHUR, computes the Schur decomposition of a square matrix
SNRM, spectral norm of an array
SRAD, spectral radius of a square matrix
SVD, singular value decomposition of a matrix
SVL, computes the singular values of a matrix
TRACE, sum of diagonal elements of a square matrix
(8) GRAPHICS & PLOTTING COMMANDS:
ANIMATE, displays grobs on the stack sequentially. You can use
the defaults, or specify your own delay between frames
(can be *very* fast), the number of times to repeat the
sequence, and even the pixel coordinates. It's just like
a ROLL REPL loop... except very fast.
Note: Charlie Patton converted 17 seconds of the Apollo
moon-walk video into HP48 GROBs and ran them with
ANIMATE, and it looked very good!
ATICK, specifies tick spacing on plot axes
EYEPT, specifies the eye-point coordinates in a perspective plot
GRIDMAP, selects the new "gridmap" plot type
PARSURFACE, selects the new "parametric surface" plot type
PCONTOUR, selects the new "pcontour" plot type
PICTURE, same as GRAPH command
SLOPEFIELD, selects the new "slopefield" plot type
WIREFRAME, selects the new "wireframe" plot type
XVOL, sets the width of the 3D plotting volume
XXRNG, sets the width of the 3D target mapping range for gridmap
and parametric surface plots
YSLICE, selects the new "yslice" plot type
YVOL, sets the depth of the 3D plotting volume
YYRNG, sets the depth of the 3D target mapping range for gridmap
and parametric surface plots
ZVOL, sets the height of the 3D plotting volume
(9) USER-INTERFACE COMMANDS:
CHOOSE, displays a point-and-click menu "dialog box"
INFORM, formatted multi-line input with named fields (nice!!)
MSGBOX, displays text in a centered box with shadow, then WAITs
NOVAL, placeholder for unspecified values in INFORM argument list
(10) LIST PROCESSING COMMANDS:
ADD, adds lists element-wise (see section #1 above)
DOLIST, evals an object on multiple lists
DOSUBS, evals a program or command taking arguments from a list
ENDSUBS, returns the number of loops the current DOSUBS will do
HEAD, first element in a list or first char in a string
(identical to CAR in Donnelly's Tool Library)
DeltaLIST, list of first finite differences of list objects
SigmaLIST, sum of the elements in a list
PiLIST, product of the elements in a list
NSUB, returns the current list pointer value during a DOSUBS
REVLIST, reverses the order of the objects in a list
(like REVERSE in Donnelly's Tool Library)
SEQ, list of results from repeated execution of an object
(like a FOR/STEP loop but the results go into a list)
SORT, sorts elements in a list into ascending order, or sorts a
list of lists using each list's first element as the key
(can be done with LSORT/QSORT in Donnelly's Tool Library)
STREAM, executes an object on first two elements of a list, then
again on the result and the 3rd element, etc. Allows
easy creation of things similar to SigmaLIST and PiList.
TAIL, returns a decapitated list or string (see HEAD above)
(identical to CDR in Donnelly's Tool Library)
(11) SYSTEM COMMANDS:
CLTEACH, clears the 'EXAMPLES' directory created by TEACH
CYLIN, sets polar/cylindrical coordinate mode
FREE1, like 1 FREE (see section #2 above)
MERGE1, like 1 MERGE (see section #2 above)
PINIT, port initialize, esp. important for 4-Meg RAM card users
RECT, sets rectangular coordinate mode
SPHERE, sets polar/spherical coordinate mode
TEACH, loads the Owner's Manual examples into a dir in HOME
VERSION, returns the operating system ROM version string and a
copyright notice, like this:
2: "Version HP48-R" <-- means version "R"
1: "Copyright HP 1993"
Note: See FAQ answer 2.4 for details about the versions.
XRECV, Xmodem protocol receive (binary mode only)
XSEND, Xmodem protocol send (binary mode only)
(12) MATH COMMANDS:
LININ, tests whether an equation is linear in a given variable
NDIST, normal probability density
PCOV, population covariance of SigmaDAT
PSDEV, population standard deviation of SigmaDAT
PVAR, population variance of SigmaDAT
RKF, solves initial value problem using Runge-Kutta-Fehlberg
RKFERR, change in solution and absolute error using RKF
RKFSTEP, next solution step with given error tolerance using RKF
RRK, solves initial value problem using Rosenbrock & RKF
RRKSTEP, next solution step with given error tolerance using RRK
RSBERR, change in solution and absolute error using Rosenbrock
(13) MENU NUMBERS & KEY CODES.
Many menu numbers have changed, so software that uses # MENU or #
TMENU may not work the same as in the HP 48S/SX. (Specifically,
only menu numbers 0-3, 28, 30, and 42-59 are the same). Likewise,
almost all of the shifted keycodes correspond to new commands and
menus, which programmers must take into account; for example, the
"RAD" key on the S/SX had the keycode 82.2, but it's 21.2 on the
G/GX. The left-shift key, which was orange on the S/SX, is now
purple [officially "lavender"], and the right-shift key which was
blue on the S/SX is now green [officially "teal"] on the G/GX.
Also, the digit-key menus can be activated by both shift keys;
left-shift gives the softkey menus like in the S/SX, but the
right-shift gives the new user-friendly full-screen menus.
The unshifted keys remain identical to the S/SX, except for a
cosmetic color change to match the very dark green of the
calculator case.
(14) MANUALS
The G/GX comes with two manuals, a "Quick Start Guide" for
beginners, and a cost-cutting, slimmer owner's manual called the
"User's Guide" which has only 21 pages about programming, since HP
figures that the huge majority of all 48 owners never program it
anyway. The power users can buy the optional "Advanced Users
Reference Manual" (similar to the S/SX's "Programmer's Reference
Manual") which covers programming and the many commands that are
not mentioned in the User's Guide. There is no "Quick Reference
Guide" like the S/SX came with, although the case still has a
pocket for one. Jim Donnelly has marketed a nice pocket guide,
but it's too wide to fit in the case's pocket. The User's Guide
is not spiral bound, but is made to open fully and last a long
time, since it's not just glued but has sewn signatures like real
books, and is printed on quality paper.
(15) FLAGS
Some previously "unused" flags are now used. They are:
-14 Clear = end-of-period payment mode (for TVM calculations)
Set = beginning-of-period payment mode
-27 Clear = display symbolic complex numbers in coordinate form
e.g. '(X,Y)'
Set = display symbolic complex numbers using 'i'
e.g. 'X+Y*i'
-28 Clear = plot multiple equations like the S/SX does (serially)
Set = plot multiple equations simultaneously
-29 Clear = include axes in plots (like the S/SX does)
Set = omit axes from 2D and statistics plots
-30 is no longer used (it never did anything useful anyhow)
-54 Clear = tiny matrix elements get rounded to zero
Set = leaves matrix elements alone
The default setting of all these flags is Clear (as in the S/SX).
(16) FLAG BROWSER
There is a System Flag browser which shows the flag number, shows
whether it's set or clear, lets you toggle it, and shows in
English what the current setting means.
(17) CHARACTER BROWSER
While programming, if you want to type any character at all, press
CHARS and a screenful of ASCII characters is displayed that you
can browse with the arrow keys, and not only does the screen also
show the ASCII code (NUM value) and even the shortcut keyboard key
sequence (if any) for each character, but if you press ECHO, it'll
be "typed" into your program. There's no need any more for the
alpha keyboard table.
(18) DIRECTORY MAINTENANCE
Press right-shift VAR to launch a Variable Browser which is a
complete memory manager. You can tag multiple objects and copy,
move, or delete them all with a single keystroke; there's even a
Mark All and an Unmark All, like a real computer. It's slow,
however, and has been obsoleted by the very fast PCT library.
(19) FRACTIONAL UNIT POWERS
The S/SX only handled integer powers of units correctly, but the
G/GX can use any real number as a unit power.
(20) NAME PLATE
The case has a rectangular indentation in the back like the HP
95LX and 100LX, and it comes with an adhesive metal nameplate that
you can get engraved with your name. ($5 at EduCALC if ordered at
time of purchase).
(21) XLIB NAMES
All of the new commands in the GX are XLIB names, and therefore
take 5.5 bytes in programs. The commands common to the SX and GX
take 2.5 bytes each, as they did in the SX.
(22) INPUT FORMS and CHOOSE BOXES
Many operations have two menu types: the old SX style, and a new
"drop-down" menu and "input forms" that have the feel of computer
dialog boxes. Especially useful for the HP48 beginner.
(23) ENHANCED PRECISION
The internal precision of at least some of the matrix routines has
been improved; INV gets better answers on square matrices than the
SX did. HP has not released information about which routines were
improved, how, and by how much.
(24) IMPROVED DISPLAY
The LCD introduced with revision M of the G/GX is easier to read
since it has higher contrast between on/off pixels. It has a
slower cycle response time, however, making it difficult to use
for rapid-motion video games or any other rapid animation.
*******************************************************************
* Appendix D: The EquationWriter Bug & Rev J Bugfix
[ The following was taken from a posting by Joe Horn. ]
Rev A-E EquationWriter Bug & Rev J Bugfix
-----------------------------------------
observed by Joe Horn
+------------------+
| Rev E behavior |
+------------------+
Clear flag -53 first (the Precedence Flag).
On a Rev E, put '((1+2)/(3+4))^5' on the stack and press down-arrow.
You'll see:
5
/ 1+2 \
| --- | (A)
\ 3+4 /
which is as it should be. But now press [orange-shift] [+]; see the
message "Implicit () off" momentarily; press [left-arrow] (not
backspace), then press the [EXIT] softkey. The expression gets
mangled into this:
1+2
----------- (B)
(5)
(3+4)
which is not equal to expression (A) above! Bug, yes? Press [ON] to
abort the process.
Now set flag -53, then repeat the above procedure. First you see:
5
/ 1+2 \
| --- | (C)
\ 3+4 /
which is the same as (A) above; but continuing as before, you see:
(5)
/ 1+2 \
| ----- | (D)
\ (3+4) /
which *is* equal to the original. Thus the bug can be worked around
by keeping flag -53 set (not a pleasant solution).
+------------------+
| Rev J behavior |
+------------------+
Major difference: after pressing down-arrow, Rev J goes directly into
graphic mode, so you have to press ON and then EXIT to get into the
equation editor (which Rev E goes directly into). But that's petty
cash compared to the following big change.
The same sequence of operations, first with flag -53 clear, then set,
exactly as detailed above, yields these four displays in a Rev J:
5
/ (1+2) \
| ----- | (A')
\ 3+4 /
(notice the extra parentheses?) and then:
5
/ (1+2) \
| ----- | (B')
\ (3+4) /
which *is* equal to (A'); nothing at all like expression (B) above!
and then:
5
/ (1+2) \
| ----- | (C')
\ 3+4 /
which is the same as (A') above; and then:
5
/ (1+2) \
| ----- | (D')
\ (3+4) /
which is also equal to (A'). No bug in Rev J.
SUMMARY: Rev A-E have a bug in the EquationWriter that can mangle
expressions if flag -53 is clear (the default) and if "Explicit
Parentheses" mode is toggled. This bug has been fixed in Rev J.
Unfortunately (as you can see above) Rev J *always* puts parentheses
around polynomial numerators. It is therefore impossible to use the
->GROB command on a Rev J to create a GROB that looks like expression
(A) above; the simplest that can be had is expression (A').
Another minor change, while I'm at it: Rev A-E don't change the menu
when you press REPL; Rev J automatically flips to the appropriate
RULES menu.
None of these changes are documented anyplace that I'm aware of.
Please post any corrections & additions you find. Thanx.
-Joseph K. Horn- -Peripheral Vision, Ltd.-
akcs.joehorn@hpcvbbs.cv.hp.com
Disclaimer: I don't work for HP, EduCALC, or anybody else.
******************************************************************
* Appendix E: Compact Data Storage:
From Jim Donnelly (jimd@cv.hp.com):
A simple length-encoding technique can be put to use for a
free-format, very compact multi-field data storage system.
Two tiny programs, SUBNUM and STRCON are here to help the
process, and are listed near the end of this note. At the
end of the note is a directory that may be downloaded into
the HP 48 that contains the examples.
The principle is to store starting indices in the beginning
of a string that point to fields stored subsequently in the
string. The indices are stored in field order, with an
additional index at the end to accommodate the last field.
There are several small points worth mentioning:
1) Fields may be 0-length using this technique.
2) The execution time is uniform across all fields.
3) This technique saves about 4 bytes per field after
the first field, because the string prolog and length
are omitted for fields 2 -> n.
EXAMPLE:
--------
Indices | Fields
Character | 1 11111111 12222222222
Position : 1 2 3 4 |567890 12345678 90123456789
+--+--+--+--+------+--------+-----------+
String : | 5|11|19|30|Field1| Field2 | Field 3 |
+--+--+--+--+------+--------+-----------+
This is a string that contains 3 fields, and therefore 4
index entries. The first field begins at character 5, the
second field begins at character 11, and the third field
begins at character 19. To keep the pattern consistent,
notice that the index for field 4 is 30, which is one more
than the length of the 29 character data string.
To extract the second field, place the string on the stack,
use SUBNUM on character 2 to extract the starting position,
use SUBNUM on character 3 to extract the (ending position +1),
subtract 1 from the (ending position+1), then do a SUB to
get the field data. NOTE: The index for field 1 is stored
as character code 5, NOT "5"! To place the field index for
field 1 in the string, you would execute "data" 1 5 CHR REPL.
PROGRAM:
--------
The following program accepts an encoded data string in
level 2 and a field number in level 1:
DECODE "data" field# --> "field"
<< --> f
<<
DUP f SUBNUM ; "data" start -->
OVER f 1 + SUBNUM ; "data" start end+1 -->
1 - ; "data" start end -->
SUB ; "field" -->
>>
>>
DATA ENCODING
-------------
The following program expects a series of 'n' strings on
the stack and encodes them into a data string suitable
for reading by the first example above.
The programs SUBNUM and STRCON are used to assemble the
indices.
ENCODE field n ... field 1 n --> "data"
<< DUP 2 + DUP 1 - STRCON --> n data
<<
1 n
FOR i
data i SUBNUM OVER SIZE ; ... field index fieldsize
+ data SWAP ; ... field "data" index'
i 1 + i + SWAP CHR REPL ; ... field "data"'
SWAP + 'data' STO ; ...
NEXT
data ; "data"
>>
>>
In this example, four strings are encoded:
Input: 5: "String"
4: "Str"
3: "STR"
2: "STRING"
1: 4
Output: "xxxxxSTRINGSTRStrString" (23 character string)
(The first five characters have codes 6, 12, 15, 18, and 24)
VARIATION:
----------
The technique above has a practical limit of storing
up to 254 characters of data in a string. To overcome
this, just allocate two bytes for each field position.
The code to extract the starting index for becomes a
little more busy. In this case, the index is stored as
two characters in hex.
Indices | Fields
Character | 11111 11111222 22222223333
Position : 12 34 56 78|901234 56789012 34567890123
+--+--+--+--+------+--------+-----------+
String : |09|0F|17|21|Field1| Field2 | Field 3 |
+--+--+--+--+------+--------+-----------+
<< --> f
<<
DUP f 2 * 1 - ; "data" "data" indx1 -->
SUBNUM 16 * ; "data" 16*start_left_byte -->
OVER f 2 * SUBNUM + ; "data" start
OVER f 2 * 1 + SUBNUM ; "data" start end_left_byte -->
16 * 3PICK f 1 + 2 *
SUBNUM + 1 - ; "data" start end -->
SUB ; "field" -->
>>
>>
TWO VERY TINY HELPFUL PROGRAMS
------------------------------
SUBNUM "string" position --> code
<< DUP SUB NUM >>
STRCON code count --> "repeated string"
<< --> code count
<< "" code CHR 'code' STO
1 count START code + NEXT
>>
>>
A DIRECTORY YOU CAN DOWNLOAD
----------------------------
This is a directory object. Cut after the === to the end of
the file and download to your HP 48 using the ASCII transfer.
========================================================================
%%HP: T(3)A(D)F(.);
DIR
DECODE
\<< \-> f
\<< DUP f
SUBNUM OVER f 1 +
SUBNUM 1 - SUB
\>>
\>>
ENCODE
\<< DUP 2 + DUP 1
- STRCON \-> n data
\<< 1 n
FOR i data
i SUBNUM OVER SIZE
+ data SWAP i 1 +
SWAP CHR REPL SWAP
+ 'data' STO
NEXT data
\>>
\>>
STRCON
\<< \-> code count
\<< "" code CHR
'code' STO 1 count
START code
+
NEXT
\>>
\>>
SUBNUM
\<< DUP SUB NUM
\>>
END
******************************************************************
* Appendix F: Various useful functions
Begin OBJFIX.DOC
-----------------------------------------------------------------------
OBJFIX by HP for SX and GX
When a binary object received by Kermit on the HP-48 is
left as a string beginning with HPHP48, OBJFIX will
extract the HP-48 object if the only problem is that
extra bytes got appended to the end.
OBJFIX takes a variable name in stack level 1 and
modifies the contents of the variable if no other
problems are detected.
[Note: This is like FIXIT by Horn & Heiskanen on Goodies
Disk #8, but this one is by HP and so I suppose it's
more reliable. Although it fails the test cases
included with FIXIT, that may be because they were
artifically contrived cases. Try both on real-world
downloads that need fixing. Which do you like better?
-jkh-]
-----------------------------------------------------------------------
End OBJFIX.DOC
--------Cut-Between-the-Lines:-Begin-OBJFIX.ASC-----------------------
%%HP: T(3)A(D)F(.);
"D9D202BA81D9F81B2040D9D20F2A26DA91629C8145126489162C23072C80CCD2
0BD0008FB9760147108134164142C2818F24D534501008B2F41643150D73B840
58405438314A161966D2BF6BF6A6F5BE16314213114334CF8208A6F58F235A04
55136D7D4EA494D231A1CA101110131CA130DBE284F8FC0760D41198F29960D4
130142119EA1408F5E0108D341503223072D70B2130B21301460"
--------Cut-Between-the-Lines:-End-OBJFIX.ASC-------------------------
Begin FIXIT.DOC
-----------------------------------------------------------------------
(Comp.sources.hp48)
Item: 139 by akcs.joehorn@hpcvbbs.cv.hp.com [Joseph K. Horn]
and mheiskan@hut.fi [Mika Heiskanen]
Subj: Fixit v3.2, repairs bad downloads
Date: 14 Jul 1992
PURPOSE:
-------
Converts a badly uploaded string into the original object.
THEORY:
------
A lot of folks upload HP 48 objects poorly, such that when you
download them, you just get strings full of garbage that look
something like this:
"HPHP48-E#c&r$a%p@!*!..." [looks familiar, eh?]
That's because they uploaded it using XMODEM, or managed to screw it
up some other way. The following FIXIT program takes such a string
and extracts the actual HP 48 object that they originally intended to
upload (if at all possible).
Such object extraction can be done by hand, but it's too dangerous.
FIXIT minimizes the danger of Memory Clear. It checks whether the
extracted object is a valid one, and if not, drops it from the stack
before the HP 48 attempts to display it. All of the many bad
downloads I've archived over the years are fixed by FIXIT, whereas
about half of them cause a Memory Clear when extracted manually. No
guarantees, however. Use at your own risk.
The actual extraction is done by a "Code object" written by Mika
Heiskanen. The User RPL "shell" around this code object is what
minimizes the danger of Memory Clear; it was written by Joe Horn.
INSTRUCTIONS:
------------
BACKUP YOUR MEMORY, just in case the string contains a logic bomb.
Place the bad download on the stack (see "HPHP48-...") and run FIXIT.
Possible results:
(1) No error: the object was extracted successfully and is on level 1.
(2) "Bad Argument Type" error: you didn't have a string on level 1.
(3) "Bad Argument Value" error: the string wasn't of the proper form;
it must be an "HPHP48-..." downloaded string.
(4) "Invalid Definition" error: the object was mangled in transmission
so badly that its end was lost; the object cannot be extracted.
(5) "Undefined Result" error: there is no HP 48 object in the string.
(6) "Recover Memory? YES/NO": the string contained a bomb, and FIXIT
detonated it. Press YES to sift through the shrapnel and rubble
in a feeble attempt to resurrect the dead. Press NO to bury them.
EXAMPLES:
--------
To do the following examples, download the FIXIT directory to your HP 48
and get into it.
(1) Press HI. See "HPHP48-E%$@#%@...", a badly uploaded download.
Before pressing FIXIT to fix it, try doing what we all used to do:
press EDIT to see if we can recognize anything (usually a futile
attempt). We see:
"HPHP48-E%@$#%$@...
<< Melancholy Baby >>"
But looks can be deceiving; press ON to exit the editor, and then
press FIXIT to extract the intended upload:
<< Happy Camper >>
(2) Press WTAV; see another garbage download. But EDIT refuses; the
string contains nulls. Press FIXIT; see successfully extracted
directory.
(3) Press BAD1. Notice that it looks exactly like WTAV. (Press WTAV,
compare, then DROP). But its ending is all messed up; manually
extracting WTAV from BAD1 can cause Memory Clear. Press FIXIT and
see "Error: Invalid Definition" indicating that the object inside
BAD1 is so mangled that its end cannot be located.
(4) Press BAD2. Looks like WTAV again. But its body is messed up;
manually extracting it would create an External object that could
cause Memory Clear if evaluated. Press FIXIT and see "Error:
Undefined Result" indicating that there is nothing recognizable
inside BAD2.
-----------------------------------------------------------------------
End FIXIT.DOC
--------Cut-Between-the-Lines:-Begin-FIXIT.ASC------------------------
%%HP: T(3)A(D)F(.);
"69A20FF7CE20000000402414442340C2A203B000840584054383D25403A20FF7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"
--------Cut-Between-the-Lines:-End-FIXIT.ASC--------------------------
*******************************************************************
(Shamelessly lifted from the HP-41C manual:)
The LASTX function is useful in calculations where a number occurs
more than once. By recovering a number using LASTX, you do not
have to key that number into the calculator again.
For example, calculate:
96.704 + 52.394706
--------------------
52.394706
Keystrokes: Stack:
------------------ --------------------
96.704 ENTER 96.704
52.304706 + 149.098706
LASTX 149.098706
52.304706
/ 2.84568265351
@
@ This is a version of LASTX for the HP 48
@
%%HP: T(3)A(D)F(.);
\<< DEPTH \-> n
\<< LASTARG DEPTH n
- DUP \-> s
\<< ROLLD s 1 -
DROPN
\>>
\>>
\>>
******************************************************************
* Appendix G: Rotation rate to angular frequency conversion bug
[Editor's Note: A counter point to this bug report is provided at
the end appendix]
By: Wlodek Mier-Jedrzejowicz
wlodek@ic.ac.uk (or if that fails, try wacm@doc.ic.ac.uk)
Posted to comp.sys.hp48 on April 29, 1994
----BEGIN QUOTED MATERIAL-----------
ROTATION RATE TO ANGULAR FREQUENCY CONVERSION BUG
There is a rotation rate conversion bug in the HP48G/GX which I have
not seen reported here before, so after discussion with the folks at
Corvallis I am posting this description. Warning: it is 159 lines long!
First - an example. Put the unit object 60_rpm in level 2 and the unit
object 1_r/s in level 1, then execute the command CONVERT. You are
asking the HP48 to convert a rotation rate of 60 revolutions per minute
into an angular frequency in radians per second. 60 rpm is 1 revolution
per second, or 2pi radians per second. No HP48G/GX will give this answer!
Not everyone uses rpm or is even aware of the existence of this unit -
it is one of the extra units in the UTILS menu of the Equation Library -
so here is a second example - add 2pi radians per second to one Hertz.
Put 6.2832_r/s in level 1, 1_Hz in level 1, and add. You are adding an
angular frequency of two pi (one cycle) per second to a rotation rate
of one per second, so the result should be a frequency of two Hertz. On
an HP48S/SX that is the answer. On an HP48G/GX it is not.
When units are converted, by CONVERT, or during arithmetic on unit
objects, the level 2 object is first turned into "base units", and then
the result is converted into the units of the level 1 object. On the
HP48S/SX, the "base unit" of angles is one rotation (or a "unit circle"
or a revolution or a cycle). So, the angle unit of rpm (a revolution)
or of Hz (a cycle if Hz is treated as a rotation rate) is already in
base units - conversions to angles involving rpm and Hz automatically
work correctly. On the HP48G/GX, the "base unit" of angles is the
current angle mode (DEG, RAD or GRAD) - so any conversion from rpm or
Hz (or any formula which works in cycles, rotations, revolutions, unit
circles) to angles should be preceded by a conversion from the unit
circle to the current angle. Apparently no-one noticed this would be
necessary, because it all worked automatically on the HP48S/SX.
So, when you convert 60_rpm to units of _r/s, an HP48G/GX converts not
60 rotations but 60 "base angle units" per minute to radians/second. In
RAD mode, you get 1 radian per second. In DEG mode you get 1 degree per
second, and in GRAD mode you get 1 grad per second (in each case
expressed in radians). That's three different answers, none of which is
correct! Exactly the same happens if you convert 1_Hz to angles per
second, and the inverse mistake is made if you convert angles per time
to cycles or rotations divided by time.
I first learned of this bug from a member of HPCC (the British club for
users of HP handhelds), Peter Embrey. He describes his troubles in
articles in the first two 1994 issues of our club journal, DATAFILE (in
Volume 13 number 1 pages 12 to 14 and V13n2p6). He was calculating the
energy stored by a flywheel - given by the formula (1/2)*I*omega^2 and
after a time he decided the answers had to be much too big when he
CONVERTed from kg*m^2*(r/s)^2 to W*h on an HP48GX. It turns out that
(r/s) are the correct units to get the right answer, but the GX was
converting to degrees per second as it was in DEG mode, so his answer
was too large by a factor of (360/2pi)^2 - a factor of about 3,300. In
this case, his HP48SX was not much better, since it converted from
radians to unit circles. The way to get the correct answer is to use an
HP48G or GX in RAD mode - or to divide out the radians from the formula
before using CONVERT. This is not yet a bug, but needs as much care as
does use of temperature units on the HP48. But when Peter tried to deal
with the problem by working in rpm, he came upon the bug described
above. My thanks to Peter for putting me on the trail!
Apparently this bug not been reported before - at least my friends in
HP tell me that it was not on their list of known problems until I told
them of it. (This means it is not fixed in the new revision R.) Why not
- does everyone know about it and work around it without thinking to
tell anyone else? Or does no-one use their HP48 to do calculations on
rotating bodies - or do most people do calculations with rotating
bodies in such a way that they do not encounter this problem? Could
there be hundreds of students and engineers out there calculating and
designing things on their HP48G/GX and getting wildly inaccurate
results? Has anyone built a disk drive or a jet engine which rotates
far too fast and will disintegrate because of this? No, of course not,
all engineers know that any design calculation absolutely must be
repeated on two entirely separate calculators or computer programs! :-|
Maybe some students have lost marks in exams because of this though -
but please, this is not intended to restart the discussion as to
whether calculators should be allowed in exams!
I want to underline again that apparently no-one has reported this
before - which must mean that few people have been affected by it. It
is therefore not a good reason to throw away your HP48G/GX or get on a
high horse and demand that HP replace your HP48G/GX - but I think it is
important that people be warned so they can take appropriate avoiding
action. The rest of this message goes into more detail - if you never
worry about rotation calculations then you can safely ignore the rest -
though you might find it interesting, so don't stop yet :-)
One way to avoid this would be to add a new unit to the HP48 - call it
what you like - the "cycle" or "rotation" or "revolution" or "unit
circle". As I wrote above, this is already implied in the HP48S/SX; to
see this on an HP48S/SX, put 360 degrees in level 1 and execute UBASE -
the result is 1, meaning that 360 degrees are equivalent to one base
unit of angle measurement, but that there is no named HP48 unit
corresponding to this. In contrast, UBASE on an HP48G/GX considers the
base unit of angle measurement to be the radian, even though CONVERT
behaves as though the base unit is the current angle mode. There appear
to be two different norms for base angle units on the HP48G/GX!
The whole subject gets very little mention in HP's manuals. In the
original HP48SX manual (two volumes, spiral bound), the section on
"Dimensionless Units of Angle" in chapter 13, on page 198, warns the
reader about the danger of using dimensionless units and states how
angle units and scalars are treated. In the later HP48S and HP48SX
manual (one volume), the same warning is given in "Converting
Dimensionless Units of Angle", on page 13-12. The HP48G Series User's
Manual, in "Converting Angular Units" on page 10-7, says that
conversion will interpret a scalar according to the current angle
mode setting. (A scalar is a pure number with no units.)
For a detailed description, look in the HP48S/SX edition of "HP48
Insights Vol II", section 21.4.3. This book is written by Dr Bill
Wickes, who was the design team leader of the HP48SX, and who wrote
the "Insights" books largely to provide the sort of explanations and
details that get left out of manuals. A good explanation of angle units
is exactly the sort of thing one can find there! He explains the
pitfalls and unavoidable contradictions of working with angles in the
HP48 units system and points out that the HP48S/SX make the somewhat
arbitrary choice of using 2pi as the base unit of angles, thereby
making conversions between angles per time and Hertz work correctly.
Maybe no-one on the HP48G/GX team read this while they were making
changes from the HP48S/SX! Why did they change the base unit at all?
Most likely they were trying to deal with another contradiction: the
units system lets you add pure numbers to angles, since both are
dimensionless. If you add the number 1 in level 2 to the unit object
0_r in level 1 on an HP48S/SX, the number 1 is treated as 1 base unit,
or 2pi radians, and the result is 6.2832_r - but if you take the SIN of
the number 1 instead, it is not treated as 2pi, but as 1 unit of the
current angle mode. The change made on the HP48G/GX does resolve this
contradiction, but at the cost of introducing the bug described above.
As mentioned, a way to resolve the problems involved would be to add
the angle unit "cycle" explicitly to the HP48 units system. Hz would
then be treated as cycles per second when used in calculations
involving rotations - rpm would be treated as cycles per minute, and
conversions would go from cycles to the appropriate angle units. This
suggestion was made by Peter Embrey in his articles, and the folks at
HP accept that this is a good solution - but they have not implemented
it yet. In the meantime, be very, very careful when converting between
units of rotation rate and units of angular frequency. I would urge
everyone who does not yet have a copy of Insights II to buy one and
read the relevant section - maybe that will even entice Bill Wickes
into publishing his long-awaited HP48G/GX version of the book!
I have not yet mentioned solid angles. In principle there should be no
problem - on both the HP48S/SX and the HP48G/GX the base unit of solid
angle is a "unit sphere", or 4pi steradians. On the HP48S/SX you can
add the pure number 1 to 0_sr and get 12.5664_sr (4pi steradians). The
HP48G/GX manuals imply that exactly the same should happen, but on my
(version L) HP48GX this gives the error message "Inconsistent Units".
This is yet another undocumented difference between the Series S and
Series G but at least it is no bug!
Apologies for making this description so long, I hope most people will
agree that a subject like this deserves a careful description! For my
next trick - some details on the HP48 Random Number Generator.
----END QUOTED MATERIAL-----------
Additional insight from Eric Haas (ERICHAAS@delphi.com)
"The angular conversion bug is actually in the definition
of the rpm unit. If you put 1_rpm on the stack, and type
UBASE, you get 1.66666666667E-2_1/s. Notice that there
is no angular unit in the definition. If the rpm unit is
instead defined as 6_=F8/s, all conversions to and from
rpms will work just fine. As an easy work-around, define
the unit RPM as 6_=F8/s and use that instead of the
built-in unit.
If desired, one could also define the unit HZ as 60_rpm
or 360_=F8/s. However, as Hz is sometimes used to describe
things other than rotation rates, such a definition
would not be appropriate for all circumstances."
******************************************************************
* Appendix H: How to make a Serial Cable for your HP48
From: prompt@xs4all.nl (Frank A. Vorstenbosch)
HOW TO MAKE A SERIAL CABLE FOR YOUR HP48
========================================
THE CONNECTOR FOR YOUR HP48
The connector used in your HP48 is a 4 pin (i.e. male) connector,
with pins spaced 2 mm (NOT 0.1") apart. These connectors are not
readily available in stores so you'll have to improvise. If you
happen to have a broken floppy drive or harddisk lying around,
look inside and see if you can find a connector there that will fit
the HP48. Do not use a 0.1" connector, as this will damage the
pins in your calculator.
If you can't find a usable connector, then you'll have to make one
yourself. For this you need four pins taken from a wire-wrap IC
socket (available from Radio Shack or some other shop catering for
DIY electronics). The smallest IC socket available usually has 8
pins; so don't worry if you damage a pin while removing it from the
hard plastic socket. The pins of the wire-wrap socket are about
1" long, thereby making soldering them easier than standard sockets.
Next, solder a 'fork' from thin rigid metal wires, to hold the four
IC pins spaced at exactly 2 mm while you glue them together with
superglue. Glue a plastic 'handle' to the four IC pins to be able
to remove the connector from the HP48. You can also indicate the
top side of the connector on this handle.
Note that the hole in the HP48 in which the connector should go
is not symmetrical; the pins are nearer to the top of the calculator
than the bottom, and you can use this to make it difficult to insert
the connector the wrong way up.
Connector to plug
in your HP48 (F) HP48 connector (M)
______ ______
|oooo| |....|
\____/ \____/
pin 4 pin 1 pin 1 pin 4
MAKING THE CONNECTIONS
You can use either a 9 or a 25 pin female sub-D socket for the
PC-side of the cable.
9-pin RS232 25-pin RS232
connector (F) connector (F)
pin 5 pin 1 pin 13 pin 1
------------- ---------------------------
| o o o o o | | o o o o o o o o o o o o |
\ o o o o / \ o o o o o o o o o o o /
--------- -----------------------
pin 9 pin 6 pin 25 pin 14
Use flexible 4-wire cable to connect the four contacts of your HP48
connector to the PC connector. Pin 1 of the HP48 should be
connected to the metal shield of the RS232 connector. Usually it
is not easy to solder this shield; first scratching the shield bare
(it has some kind of coating) using a screwdriver or a file will
help. If this doesn't work, simply leave pin 1 of the HP48
disconnected. Note that pins 2 and 3 of the RS232 connector must
be swapped when you use a 25-pin connector.
HP to PC cable
HP48 | RS232-9 | RS232-25
-----+---------+----------
1 | shield | shield
2 | 2 | 3
3 | 3 | 2
4 | 5 | 7
Before connecting the completed cable to your HP48, check for
short-circuits using an ohmmeter or multimeter set to ohms or
"diode test".
HP TO HP CABLE
If you want to use 9600 bps communication between two HP48s, then
make two HP48 connectors and simply connect the two, swapping pins
two and three.
HP to HP cable
HP#1 | HP#2
-----+-----
1 | 1
2 | 3
3 | 2
4 | 4
WARRANTY, DISCLAIMER ETC.
Although the serial interface of the HP48 is protected internally,
it is possible to damage the calculator when a wrong connection is
made. I am not responsible for any errors in this file, or for any
mistakes you may make.
******************************************************************
END PART 3 OF 4
--
Keith Maddock--madd0118@nova.gmi.edu--HomePage:http://www.gmi.edu/~madd0118
"Of course I'm crazy, but that doesn't mean I'm wrong. I'm mad but not ill"
GMI Engineering & Mgt Inst: So2,ME-Auto, Flint, MI/Freightliner Corp,PDX,OR
comp.sys.hp48 FAQ Maintainer (GX-R), Eagle Scout, Delta Tau Delta EI-B, :-)
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