umapd51@cc.ic.ac.uk (03/07/90)
Subject: ...but by every word that comes from Corvallis
This area is already getting swamped with new HP stuff, as I suggested
last week (not by HP28 alone...). The latest "word" from HP Corvallis
is the HP48SX (Scientific eXpandable) calculator, and it deserves all
the attention it is getting. Some weeks ago HP offered HP48s to a few
long-standing users of HP handhelds who are also users of this net,
asking us to post reviews when the HP48SX is announced. This was good
news for those who got a 48 early - we were happy with the arrangement
(maybe "ecstatic" is a better description) - and good news for the net -
we could provide reviews in the light of some weeks' experience,
complementing the reviews from people who are very excited after seeing
an HP48SX for a few minutes or hours. Well, the announcement was today,
Tuesday March 6, so here is my review.
Calculator design, like politics, is the art of the possible. The
HP48SX shows just how much IS possible these days. Users of the HP-41,
HP-71 or HP-28 will recognize features of all these machines, with many
extensions. People who have not used earlier HP models might like to
think of the HP48SX as Derive, in a handheld package, with the hardware,
and something like Borland's SideKick, included in the price. People
who do not know Derive (SoftWarehouse's upgrade of their muMATH PC
program to do math in numeric or symbolic mode, with graphing and other
features) can just read the following list of features. The HP48SX
handles real and complex numbers, numbers with units attached, two and
three-dimensional vectors, n-dimensional vectors and mxn dimensional
matrices. It manipulates all these in symbolic form or in numerical
form, using RPN or algebraic notation. It can handle them as equations
displayed in text-book style layout, as graphs, as equations in the form
used by languages such as Basic or Fortran, or in the form of an
object-orientated programming language. It can differentiate formulae
numerically or symbolically, and it can integrate them in both ways too
(only a couple of weeks ago it was said on this net that symbolic
integration was not possible in a calculator). Admittedly, the HP48SX
can not symbolically integrate all formulae that ARE integrable; like
the HP-28 it provides Taylor approximations and integrates a Taylor's
polynomial approximation where it cannot do a direct integration. A
neat example program uses graphics to show how a Taylor polynomial
approximation corresponds to a trig function over an increasing range as
the number of terms is increased. (The manual does not point out that
the object TSL produced by this example occupies about 10kbytes -
remember to delete the TSL list when you have finished with it.)
All these features, and lots more, have already been mentioned and,
undoubtedly, will be described again in the coming days. One needs
rather more time to realize that these are not just a random selection
of gee-whiz features all in the same calculator. They all fit together,
so one operation takes you neatly into the next one, or you can find an
alternative way to approach a problem if the way you are doing it now
does not feel right. Here are just a couple of examples where one
feature is very sensibly combined with another. First, you can combine
a custom menu with a SOLVR menu. Thus you can add any special commands
you need to the variables displayed in the SOLVR menu - if you are
solving for the unknown variable in an expression you can add, say, a
unit conversion or the SWAP2 command to the menu of variables used by
the equation. Secondly, you can plot the derivative of a function over
the top of the function itself, just by pressing a special F' menu key.
Rather than continue with a list of features, I'll now describe some of
the ways in which HP have listened to the users and added commands to do
things we have asked for on the HP-28 (or in some cases have posted
SYSEVALs for on this area). Apologies to readers who do not know the
HP-28, but you too should find this worth reading. Obviously, the
display is bigger, the speed is greater (HP say about 50% faster than an
HP-28S running at normal speed, and my favourite calculator benchmark
confirms this), and the memory can be expanded (memory expansion with
plug-in RAM cards works very much as on the HP-71B - a card is either
merged with main RAM or it acts as stand-alone free ported RAM - the
card can be one or the other, but not both - some users may be unhappy
about this). One keyboard instead of two was demanded by many people
who found it impossible to use the HP-28 in one hand, though others will
be unhappy with the change. There is full I/O via two-way infrared, and
via a serial cable which can be used at a low level or with the Kermit
protocol which is built in. The menu keys can be used in combination
with the shift keys to provide up to three operations per key, AND the
whole keyboard is user-definable (being able to disable all keys except
a selected few in USR mode is very welcome - it stops users, especially
inexperienced users, doing harm by pressing a wrong key). Something I
asked for, and now have, is extended storage arithmetic - STO+ is no
longer restricted to working with stored real numbers - but why is STO^
still missing - it is available on the HP-27S! There is no fraction
arithmetic as such, but the commands ->Q and ->Qpi let users convert a
result back into a fraction, or a fraction times pi (if this gives a
simpler fraction). These operations work to the display accuracy - if
you know you are expecting a fairly simple answer then it is worth
setting a display mode showing 9 or 10 digits only, otherwise you may
well get an answer which is more accurate in terms of the calculator's
precision, but which is not the answer you want. For example one might
like:
'1/3*pi' ->NUM ->Qpi
to give the result '1/3*pi', but in STD or 12 FIX or 11 FIX modes the
actual result is '382136/364913'. A clock and alarms (appointment and
control, a la HP-41) are provided - hooray! The programmable OFF
function is there - no more SYSEVAL-ing for this - I shall recall with
nostalgia the time I spent hunting for that one on the HP-28S, and
posting it here. The UP command (only for user variables, but see Jake
Schwartz' program), checksums and byte sizes are all things for which
HP-28 programs were posted but which are now built in. Error handling
is enhanced. "Counted" strings let us do smart things such as including
the string delimiter " in a string (but strings including CHAR 0 can
still not be edited directly - you have to use SUB first to edit
substrings without the null character).
More things HP-28 users wanted: You can recover if you STO something
accidentally into a variable! LAST ARG not only replaces the name and
object on the stack but also restores the previous contents of the
variable. You can define your own RULEs - these are themselves an
extension of the HP-28 FORM subsection of ALGBRA (ALGEBRA on the HP-
28C). There are 3 character sizes - especially useful for subscripts
and superscripts in the equation entry application, but the smallest
(menu-sized) characters also allow you to put more than 22 characters on
a line - I have got as many as 63 characters on one display line this
way - it may be best if Jake Schwartz' multi-line stack display program
were to use these small characters at all times, since that would let us
see more of all long objects - Jake? Plots can be autoscaled - and
there is a command to label the axes automatically. The speed menu
contains not only the value of c, the speed of light, but also ga, the
acceleration due to a standard gravity of 1 g. Complete subdirectories
(including THEIR subdirectories) can be recalled to the stack, edited,
and replaced or stored elsewhere. HP-41 users will be delighted to know
that setting flags 1,2,3 and 4 puts corresponding numbers in the top
status line (there is no flag 0), and that large numbers can be seen
with digit separators every three digits (numbers with an absolute value
from 1,000 to 999,999,999,999 - in FIX mode only).
Mention of the HP-41 brings me to add-ons. The only CURRENTLY available
plug-in card appears to be the dealer demo ROM - with some really neat
graphics (a PC demo disk is available too, showing an HP48SX on the PC
screen doing exactly the same as the demo ROM does, and mimicking the
actions of the HP48 menu keys through the PC function keys). Plug-in
32k and 128k RAM cards are supposed to be shipping now. The plug-in HP
Solve Library ROM code is complete and cards should be shipping soon.
A Survey ROM and an HP-41CV Emulator ROM are still being worked on by
third parties (cf the corresponding HP-71B modules!), but should be
available by Summer at the latest. The HP Solve Equation Library card
is terrific - 322 equations (diagrams accompany some of these), 38
physical constants, and the Periodic Table with properties of every
element up to number 106 - there may be many more, but they haven't been
discaaavered as Tom Lehrer told us long ago (some have been since then,
but very few of us need to know their properties, even if much was known
of them). Two types of serial interface cable are available - for a PC
port (9 pin or 25 pin) or a Mac. Instead of a cable only, you can buy
an Interface Kit, with a floppy disk added - this has Kermit (which many
people have anyway) and some utility programs, including USAG which is
the equivalent of the USE key in the CATALOG menu on the HP-28. (USAG
tells you that + has an inverse, can be differentiated, and can be
used with 25 combinations of objects!) There is no equivalent of CATALOG
on the HP48SX because a 64 page pocket guide is provided instead. This
is supplemented by two manuals with a total of 850 pages. A third
Reference Manual is to be sold separately from Summer; this will contain
details of all commands (as in the HP-28S Reference Manual), but I have
been told it will contain more, including some SYSEVAL addresses! Bill
Wickes and Jim Donnelly are already writing books for the HP48SX - I am
not (yet) doing so as I would prefer to see the Reference Manual before
embarking on extensive SYSEVAL hunting expeditions. Users unhappy that
the HP48SX keyboard is not protected in a clamshell case may be happier
on learning that the HP48SX case is pretty rugged - it has been adapted
from a case used for HP instruments (voltmeters I believe).
Other accessories? Overlays will be available - some plug-in cards will
need these as they redefine the keyboard. The infrared transmitter is
designed to be used with the HP82240B printer; there is a translation
mode for owners who wish to carry on using an HP82240A instead. Other
printers can be used through the serial interface. The infrared receiver
can read information transmitted from another HP calculator - thus you
could copy all your HP-28 programs to your new HP48SX before selling
your HP-28. A program to read infrared input is included with the I/O
kit. One use of this will be to read HP-41 programs into the HP-41
emulator system, using the HP-41 Blinky module. Two HP48s can exchange
programs and data using the transmitter and receiver - does this make a
second HP48SX an accessory? (Will HP sell two-packs?) Since the serial
interface lets you connect to a PC, you can use a PC to save programs
and data, you can use the PC keyboard to type in programs, and you can
even use the PC keyboard to drive the HP48SX. In fact, you could say
that a PC is the best HP48SX accessory available!
This should be plenty for one review, I guess I'll be posting more soon.
Apologies to anyone who might be upset by the titles I have used for
this article and its predecessor - as it is the time of preparation for
Easter (and Passover) I thought it worth remembering the original text
from Deuteronomy that Jesus quoted.
Wlodek Mier-Jedrzejowicz,
Space Physics, Imperial College, London
BITNET/EARN: MIER@SPVA.PH.IC.AC.UK
Disclaimer: Neither my employer nor I claim anything, but I hope the
above will be of interest and maybe even of use.
A