cs303130@pb.usl.edu (02/22/90)
I got the SPEED program yesterday and I assume that 15 SPEED is equivalent in effect to FAST (??) (I tried to assemble FAST, from the TOOLKIT and it didn't work, yes all the checksums were correct). Also, who determined that FAST causes the calc to use more power than in normal mode? How was that determined, or did the info come from HP? What exactly does FAST do (I mean, does it directly affect OS software or hardware operation) One more thing, can someone reccommend some good books on the HP28S, especially those oriented toward the advanced programmer, and is there any published info on the hardware internals? (like in a HP technical journal perhaps) Darrin Chambers
peraino@gmu90x.gmu.edu (peraino) (02/22/90)
>From cs303130@pb.usl.edu Wed Feb 21 12:03:56 1990 >Subject: SPEED vs FAST question (HP28S) > > >Also, who determined that FAST causes the calc to use more power than >in normal mode? How was that determined, or did the info come from >HP? What exactly does FAST do (I mean, does it directly affect OS >software or hardware operation) > >Darrin Chambers FAST and SPEED work by upping the clock speed of the calc; this alone implies an increase in power consumption. If you want specific power consumption figures, wait a few more days, and I'll post the hp28 power consumption article I'm working on. ----------------------------------------------------------------------------- Bob Peraino UUCP : uunet!pyrdc!gmu90x!peraino George Mason University INTERNET: peraino@gmuvax.gmu.edu UCIS, Thompson Hall, rm 2 <- BITNET : peraino@gmuvax 4400 University Drive \ PHONE : (703)-323-2549 Fairfax, VA 22030 \- Yeah, they put us in the basement, too. -----------------------------------------------------------------------------
prestonb@hpcvra.CV.HP.COM (Preston Brown) (02/23/90)
>What exactly does FAST do (I mean, does it directly affect OS >software or hardware operation) Fast writes to a hardware register which controls the speed of the main system clock. The main clock is generated by using the time base clock (32.768KHz) as a reference and a special circuit to generate a main clock of 4MHz. The control register specifies the multiplication factor to use. The FAST programs I have seen all set the main clock to the maximum speed of 8MHZ. While this works just fine in most cases, it is operating outside of the product spec. When your battery voltage is low, it may fail; most likely resulting in a locked up machine and memory lost. The system is speced to operate at normal speed, > 3V , and a temp of 0 deg C to 40 deg C.
daver@guille.ECE.ORST.EDU (Dave Rabinowitz) (02/23/90)
In article <4282@rouge.usl.edu> cs303130@pb.usl.edu writes: >Also, who determined that FAST causes the calc to use more power than >in normal mode? How was that determined, or did the info come from >HP? What exactly does FAST do (I mean, does it directly affect OS >software or hardware operation) The HP28S uses a 32,768 Hz crystal, like the ones used in most digital watches, as its reference clock. The CPU has to run at a much higher speed, so it's clock is generated by a voltage-controlled oscillator (VCO) whose output is divided down by some number and then frequency-locked (patent pending) to the reference crystal. For example, to get 8 MHz from the VCO you divide its output by 256 and adjust the VCO frequency until the divided frequency matches the crystal frequency. The frequency divider is programmable, and the FAST program simply changes the divisor. For example, if you divide by 128 instead of 256 the clock frequency will become 4 MHz, etc.. The speed of CMOS circuitry varies significantly with voltage. The voltage obtainable from batteries goes down as the batteries age. Since the 28S has to operate reliably with relatively old batteries whose voltage has dropped, the operating speed was set to guarantee that the calculator will operate correctly until the battery voltage has dropped well below the low-battery indication. In fact, the calculator has two separate low-battery detection circuits: the first, which triggers at about 4V (new batteries put out a little over 6V), tells the software to turn on the low-battery annunciator in the display, while the second, which trips about .5V lower than the first, forces the calculator to shut down, preventing incorrect operation from destroying memory. These levels were determined to be safe for a calculator operating at the nominal speed, and are not safe for calculators operating at a higher speed, so it is possible for a FAST calculator to lose memory or otherwise get incorrect results even without the low-battery annunciator being on. The FAST program should be used only with NEW batteries, and even then there are no guarantees. As for current drain, the power dissipated by CMOS circuitry varies linearly with clock speed, so doubling the CPU speed would normally double the power. However, some of the power in the 28S is used in analog circuitry (mostly switched-capacitor) which is clocked from the 32 KHz crystal, independent of the CPU speed, so only some of the power will be doubled and the total power will increase by less than 2X (as an aside, the power varies as V^2, so the calculator dissipates more power with new batteries regardless of speed). The CPU speed only impacts CPU power, and the CPU runs only when the calculator is actually calculating something or when a key is being pressed, so when the calculator is simply displaying results and waiting for something else to do the CPU is not running and the power drain (very low) is independent of CPU speed.
umapd51@suna.cc.ic.ac.uk (W.A.C. Miev-Jedrzejowicz) (02/23/90)
Bcc: rst I heard of speed mode was via Jake Schwartz who reads and writes here too. The Danish user club described how to use this mode. Then I wrote a n RPL program which created the necessary machine language instructions to turn on speed 15 (the naximum). Then other smart folk write (wrote) direct machine language programs to do the job. I suggested in my book "Customize Your HP-28" that speeding up uses more power, and repeated this accusation in the club journal. It has since nbeen pointed out that FAST mode actually uses lkess power, since the consumption goes up less rapidly than the speed. There are othe problems though, in particular that speed mose degrades to normal mode under certain (as yet undetermined) circumstances, and HP engineers suggest that under particular circumstances (low battery?) results might be wrong in fast mode. As for books, have you heard of EduCALC? (Apologies in advance to other readers!) Wlodek Mier-Jedrzejowicz.
a634@mindlink.UUCP (Rob Prior) (02/23/90)
> prestonb writes: > > The speed reverts to normal when the ON key is pressed. This is > to allow the system to recover if it locks up because you are > running outside of the speced speed. This is the only protection > you have and you would most likely still get a memory lost if it > does get lost. This isn't the only condition in which the speed will reset itself. I have a polar plotting program that always (well, usually anyways) that seems to revert to normal speed about halfway through its calculations. (It displays the angle it's calculating on the screen as it goes, and about half-way along (About 180 degrees) it reverts to normal). Never could figure this out, and the program has no features to explain the phenomena. -- _______________________________________________________________ |Rob Prior - President, Still Animation Logo Design, Burnaby, BC| |---------------------------------------------------------------| | Mail to: Rob_Prior@cc.sfu.ca (try this first) | | ___ _ or: a634@mindlink.uucp (send here only as | | /__ /_\ a last resort...this one isn't free :) | |____/ / \____________________________________________________|
prestonb@hpcvra.CV.HP.COM (Preston Brown) (02/24/90)
>There are othe problems though, in particular that speed mose >degrades to normal mode under certain (as yet undetermined) >circumstances, and HP engineers suggest that under particular >circumstances (low battery?) results might be wrong in fast mode. The speed reverts to normal when the ON key is pressed. This is to allow the system to recover if it locks up because you are running outside of the speced speed. This is the only protection you have and you would most likely still get a memory lost if it does get lost.
pa1409@sdcc13.ucsd.edu (Steven Haehnichen) (02/27/90)
In article <1192@mindlink.UUCP> a634@mindlink.UUCP (Rob Prior) writes: >This isn't the only condition in which the speed will reset itself. I have a >polar plotting program that always (well, usually anyways) that seems to revert >to normal speed about halfway through its calculations. (It displays the angle >it's calculating on the screen as it goes, and about half-way along (About 180 >degrees) it reverts to normal). >Never could figure this out, and the program has no features to explain the >phenomena. >|Rob Prior - President, Still Animation Logo Design, Burnaby, BC| If it's anything like the PolarPlot program I wrote sometime ago and sent to gmuvax2 (didn't find news until later), the calculation process uses up tons of memory (especially at high resolutions (small steps)) to generate the plotting array. My guess is that, at some point, memory gets cramped and the HP calls the Garbage Collection internal routine to clean up the stack and such. Could it be that this also resets the clock speed? I have never seen a working copy of FAST posted and I was unable to find one anywhere on gmuvax2, but I assume it's something like SPEED which was highly erratic on my 28S. What is the difference between SPEED and FAST. (If someone wouldn't mind sending me FAST, I'd be much obliged.) I haven't been as gung-ho about hacking since the last MEMORY LOST did in about 20K. (pre-IR backups) But I am still interested in knowing when (& why) the HP resets its clock speed. Steve. shaehnichen@ucsd.edu
lishka@uwslh.slh.wisc.edu (Chris Lishka (a.k.a. Fish-Guts) ) (02/28/90)
prestonb@hpcvra.CV.HP.COM (Preston Brown) writes: >The speed reverts to normal when the ON key is pressed. This is >to allow the system to recover if it locks up because you are >running outside of the speced speed. This is the only protection >you have and you would most likely still get a memory lost if it >does get lost. Note that the hp28 can also revert back to normal speed under other conditions besides an ON key press. This happened to me several times back when I was still using fast. I believe that Bob Peraino also had this happen to him. -- Christopher Lishka 608-262-4485 "Somebody said to me, `But the Beatles were Wisconsin State Lab. of Hygiene antimaterialistic.' That's a huge myth. John lishka@uwslh.slh.wisc.edu and I literally used to sit down and say `Now, uunet!uwvax!uwslh!lishka let's write a swimming pool'."--Paul McCartney