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