bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) (02/04/88)
I recieved a preliminary copy of Dr. WAC Mier-Jedrzejowicz book,
'Customize Your HP-28C'. It is excellent and I suggest it to anyone who
owns a 28C. In it, he describes how to speed-up the 28C by changing two
capacitors. The speed increase is bout 180%. This makes a big
difference on all operations. Happily, the clock and beeper functions
are unaffected as they are controlled by a quartz clock. If you are
interested in a description of the modification, please email me. Better
yet, buy Mier's book (preliminary copies are only available 'to friends'
and the book will be ready in the Spring).
Brett L Maraldo
p.s. I want an HP28S. Is there any trade-up arrangements being made by
hp or other companies (i can put another 32k (or even 64k) in my 28C but
i can't change the software). Do you think it would simply be a matter
of changing the ROMs??
--
-------- Unit 36 Research ---------
"Alien Technology Today"
bmaraldo@watdcsu.waterloo.edu
{allegra,decvax,ihnp4,utzoo}!watmath!watdcsu!bmaraldobillw@hpcvra.HP.COM (Bill Wickes) (02/07/88)
I understand Educalc is offering a $50 trade-in of HP-28C's for 28S's. Note also that the 28S is completely new electronics compared to the 28C. The CPU, one display driver, and 64K of ROM are integrated into a single IC (there are two of these). The 32K RAM is a commercial part, not a Saturn RAM. These points mean a) you can't make a 28C into a 28S, and b) you can't add RAM to a 28S--it's hard configured.
conte@uicsrd.csrd.uiuc.edu (02/07/88)
> /* Written 11:21 am Feb 3, 1988 by bmaraldo@watdcsu.waterloo.edu in uicsrd.csrd.uiuc.edu:comp.sys.hp */ > > I recieved a preliminary copy of Dr. WAC Mier-Jedrzejowicz book, > 'Customize Your HP-28C'. It is excellent and I suggest it to anyone who > owns a 28C. In it, he describes how to speed-up the 28C by changing two > capacitors. The speed increase is bout 180%. This makes a big > difference on all operations. Happily, the clock and beeper functions > are unaffected as they are controlled by a quartz clock. `Clock functions?' What clock functions? I know that the 18C has a clock, and the two machines (18C and 28C) have the same processor (actually from the 71B). [This from an issue last summer of HP Journal] However, I had thought the clock was not accessable in the 28C. The 28S's have started shipping. The machine seems faster than the 28C, especially when plotting. Just eyeballing it I would say that 180% increase over the 28C is a reasonable description of the 28S's performance, so HP might have also incorporated this fix into the `S. Tom Conte Center for Supercomputing Research & Development University of Illinois The opinions expressed are my own, just mine, not the Center's, not Cedar's... uucp: ...!uiucdcs!uicsrd!conte bitnet: conte@uicsrd.csrd.uiuc.edu arpanet: conte@uicsrd.csrd.uiuc.edu
conte@uicsrd.csrd.uiuc.edu (02/07/88)
> `Clock functions?' What clock functions? ...
Just a clarification: I'm asking if there is a real-time clock, I know
there has to be a system clock. However, implying that the speedup
doesn't alter the `clock' suggests this isn't the system clock you're
talking about.bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) (02/10/88)
In article <44700011@uicsrd.csrd.uiuc.edu> conte@uicsrd.csrd.uiuc.edu writes: >Just a clarification: I'm asking if there is a real-time clock, I know >there has to be a system clock. However, implying that the speedup >doesn't alter the `clock' suggests this isn't the system clock you're >talking about. The CPU uses an LC time base as a clock while everything else uses a crystal controlled ocs. The mod to increase the speed of the CPU clock does not affect the Xtal clock. This means the beeper & real time clock (#123 SYSEVAL) are unaffected. The printer I/O uses the CPU clock for sync so the speed upgrade will make the printer port useless on the HP printer. Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" bmaraldo@watdcsu.waterloo.edu {allegra,decvax,ihnp4,utzoo}!watmath!watdcsu!bmaraldo