gt3398b@prism.gatech.EDU (DELANO,ANDREW DOUGLAS) (11/13/90)
I recently got a copy of the hp28 fast program. Here it is:
<<
#1FFF00F1F0302331h
#C8084612411310D5h
#3B82h SYSEVAL
#7195h SYSEVAL
#44A4h SYSEVAL
>>
Just type this in, press EVAL, and store the System Object under fast.
Now every time you press FAST, the 28 is 2x as fast.
BIG QUESTION!!!!
What effects, if any does this program have on the 28s??? Do the
batteries burn faster, does it hurt the calculator?? Somebody
who knows, please email me!!!
--
DELANO,ANDREW DOUGLAS
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt3398b
Internet: gt3398b@prism.gatech.eduumapd51@cc.ic.ac.uk (W.A.C. Mier-Jedrzejowicz) (11/18/90)
This is a re-posting of a follow-up on the subject of the HP-28S FAST
program/s. Apologies if you have already seen it - I am reposting it
because our system administrator changed the distribution to Europe
only, and I suspect this MIGHT be of interest to csh readers elsewhere.
As this topic has been brought up in several recent postings, I thought
I would post a summary of new and old information, since I believe I
started the whole thing ;-)
When I posted the first version of HP28S FAST on comp.sys.handhelds, it
used a list of binary numbers followed by a SYSEVAL - the result was
that an HP-28S would run at about double its standard speed until ON was
pressed. I got the necessary information from an article in USER, the
journal of the Danish club for users of HP handhelds, and I repeat my
thanks to them.
Since then, several smaller and faster versions have been posted, mostly
using PIG and BAG or other methods of entering a machine code program
more directly than my original method. My method had the advantage of
not requiring any machine code, nor any LONG strings of hex numbers. If
you want to learn more about machine code programming on the HP-28, look
in the archives, especially for Alonzo Gariepy's Saturn Processor notes.
Alonzo took a lot of the information in those notes from my book
Customize Your HP-28. I in turn used information provided by HP in the
HP-71 IDS documents, plus a considerable amount of work, described in
Customize...
Soon after I had posted FAST, people began to complain that their HP-28S
would spontaneously return to normal speed. I had not become aware of
the problem myself, and initially suggested they were accidentally
pressing the ON key. This was not the case, but there was no clear
pattern of what could be the problem. Earlier this year I discussed the
problem with Preston Brown at HP, and he explained that this is a
hardware problem - a circuit designed to detect pressure on the ON key
is over sensitive and things such as putting down the 28 or possibly
even small temperature changes are interpreted as a depression of the ON
key. This circuit does not cause a full reset, but it does restore a few
things to normal - in particular the speed, and the enabling of the
keyboard - this is the reason why my program in "Customize..." to
disable the keyboard also loses its effect after a while - exactly the
same problem as with FAST.
I did not initially notice the problem because an HP-28S in FAST mode
does not seem to return to normal speed so long as a program is running
- a running program seems to disable the circuit concerned. I would be
most interested if anyone can report that their HP-28S drops out of FAST
mode while running a program.
Does FAST burn up the batteries faster? Well, yes, while in FAST mode
the HP-28S is using the batteries faster, at least while it is running a
program. BUT, the gain in speed is greater than the extra use of
batteries, in other words you would actually be better off running in
FAST mode all the time if you wanted to get as much calculating done as
possible on a set of batteries. My thanks to Roger Rosenbaum of the
Puget Sound HP handhelds user club who pointed this out to me, and to
Tony Canas here at HPCC (the British club) for helping me confirm it.
The main thing to worry about in FAST mode is that the HP-28S was not
designed to run at the top speed provided by FAST (2MHz), so that when
the batteries begin to be used up there is no guarantee that all
operations will give a correct result - for example fetching a number to
the CPU may be slowed down so much that the CPU uses an incorrect value.
So, do NOT use an HP-28S in FAST mode for critical work! If you must,
then do the calculation twice and compare the results - but that takes
twice as long, which rather spoils the whole point of FAST! FAST is
ideal for some applications though, for example drawing plots and graphs
much faster, or playing games. If you want to use FAST mode and to check
whether the batteries are low, you cannot rely on the battery
annunciator nor on internal flags - use the "Battery gauge" program
posted several months ago by Bob Peraino instead - this warns you that
the batteries are getting low, well before the annunciator comes on.
Users sometimes ask for equivalent programs for the HP-28C or for the HP
48SX. Sorry, it can't be done! The HP-28C does not have software to vary
the running speed - if you MUST speed up an HP-28C you have to do it in
hardware - this was described in DATAFILE (the journal of HPCC - the
British club) and in "Customize...". The HP 48SX already runs at the
speed provided by FAST - BUT the HP 48SX CPU spends a significant
portion of its time checking and updating the display, even during a
running program. This means that an HP 48SX will not, in general, carry
out its number crunching as fast as an HP-28S in FAST mode. One point
for the 28 users! If you want maximum speed AND RS-232 connectivity, get
an HP-28S and have it modified by Friedrich Schroeder in Denmark, who
adds an RS-232 connector and a bunch of utilities, including comms, on a
chip he builds into your HP-28S. He can also sell you a ready modified
unit. FAST is one of the utilities built into these units (called an
HP-28COM), which have also been mentioned before on comp.sys.handhelds.
Sorry this has been long, but I hope the information will be of use. The
clubs mentioned above generally sell back numbers of their journals to
new members - and anyone can join - you do not have to live in the
club's own country. See my "club list" for addresses - that list too is
available from archive sites (and the HP BBS) - it's probably time I
updated it. Does anyone know if HPX is still active, or should I remove
HPX from the list?
Thank you for your attention ;-)
Wlodek Mier-Jedrzejowicz, Ph.D., Space and Atmospheric Physics, Imperial
College, London SW7 2BZ, UK
uucp address - see above
BITNET/EARN: MIER@SPVA.PH.IC.AC.UK - use this if possible
or : UMAPD51@VAXA.CC.IC.AC.UK
JANET : MIER@UK.AC.IC.PH.SPVA
Disclaimer: I hope this information is of interest; it is provided for
your interest and delectation but I accept no responsibility for the
results of any use made of it - nor do my employers nor HP.bson@rice-chex.ai.mit.edu (Jan Brittenson) (11/19/90)
In article <1990Nov18.061220.14564@cc.ic.ac.uk> umapd51@cc.ic.ac.uk (W.A.C. Mier-Jedrzejowicz) writes: > The HP 48SX already runs at the speed provided by FAST - BUT the HP > SX CPU spends a significant portion of its time checking and > updating the display, even during a running program. When does this happen? If you're refering to the top two lines of annunciators, then this is incorrect since they are not updated during execution. It's my impression that the 48 is slower mainly because it has more data types, as well as allowing types to be used in additional combinations, both of which factor up to more elaborate type dispatching. Also, the dispatch code is often sloppily done; in general type combinations more commonly used should be dispatched before less frequently used combinations. This is generally, but not always, the case.