I'm getting the itch to get back to Z80 stuff.
Has anyone used the STD bus, or have any parts?
I have a few card cages and cards
but never enough I/O cards!
In the least, I was planning on using the STD bus
just for expansion cards to a single board computer.
-- Jeffrey Jonas
In "Broadcast News" during the big layoff scene there
is at least one clear shot of a 5150. I think it was
a dual floppy model.
Regards, Jim
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> Date: Sun, 11 May 2008 16:25:18 -0700
> From: Al Kossow
> It was Sidhu, Ron Hochsprung, Larry Kenyon, and Alan Oppenheimer
>
> http://www.patentstorm.us/patents/4689786-fulltext.html
>
> Ron came up with the low-level stuff. He also did the PC Appletalk
> card and firmware (and tons of other stuff since then).
Would this be the same Ron Hochsprung who served as the computer
center manager at IIT in Chicago around 1967?
Cheers,
Chuck
Allison wrote:
> It would not be diskless only floppy less.
Er, I don't what to get into the subject of what a "disk" is, but
I'll concede that the beast would have secondary storage.
> IF you really want to enjoy the vintage experience you can include a
> floppy controller but be warned...They are a PAIN to use and program.
> The most important detail is the unless you include DMA (more parts)
> the cpu does all the heavy lifiting in real time and that requires
> tight code or some hardware tricks (more parts). It stops getting
> simple real fast. Then there are the various floppies with their
> interface quirks.
I disagree--I've been known to program a floppy controller or two in
my time and never found them particularly nasty--except for the
WD1781 which had a really annoying tendency to hang during some
operations. WD never fixed that--the 'B' part still had the problem
when they discontinued it. Our fix involved timing the operation and
then resetting the controller if it went out to lunch. So when the
PC came along when a drive-not-ready condition would cause the 8272
to hang, it seemed like old home week.
(Does anyone have a datasheet for the WD1781? I can't seem to locate
my copy anymore.)
A WD1770 is very easy program (as are most of the WD x7xx parts),
requires very little in the way of interface logic and can be
serviced with non-DMA data transfers, even on a 2MHz 8080. (Herb
Johnson has a good section on floppy transfer vs. CPU speed on his
retrotechnology.com site.) A 4MHz can easily handle DD 8" drives
without DMA, which should mean that HD 1.44MB drives should also
work. Don Tarbell's first 8" controller handled SD 8" on a 2MHz 8080
quite reliably.
The topic interested me at one time because I wondered if it was
possible to read DD 8" floppies without DMA with a 2MHz 8080. I
think it is, but you have to resort to some strange programming
tricks. I believe that Herb has my notes on this.
Cheers,
Chuck
Date: Sun, 11 May 2008 21:44:31 -0700 (PDT)
From: "Eric Smith"
> No, the MK-90 is smaller, and weighs only 0.7 kg:
>
> http://www.taswegian.com/MOSCOW/mk-90.html
>
> When I first heard of it I was skeptical of the claim that
> it used a PDP-11-compatible processor, but since then I've
> verified it by actually running my own PDP-11 code on one.
Hmmm. My guy has it listed under "calculators". But I think the MK
87 might even beat the MK-90:
http://www.leningrad.su/museum/show_calc.php?n=173
It's not clear that one can actually get to the CPU at a machine-
language level, however.
Cheers,
Chuck
Does anybody know of an equivalent or source for replacement DEC 8235 ICs?
They're AND-OR-INVERT gates used as bus drivers on the TD8E (and probably
other OMNIBUS boards).
Thanks,
Bob Armstrong
The question of which DOS-era floppy backup program was "best" has
always bothered me over the years, so today I spent the better part of
an afternoon satisfying my curiosity. (By "floppy backup program", I
mean programs that intelligently used high-speed DMA to format and write
backup data while the computer was doing other things in the background,
like reading from the hard disk and compressing the data.)
Results are here, for the curious:
http://www.oldskool.org/guides/dosbackupshootout
If I missed an obvious one that runs on XT-class hardware, let me know.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
Can somebody with a Miniscribe 6085 tell me the value (or at the very
least the color code) of the inductor near CR16, RP17, Q17, C59,
etc. ? (the actual location marking on my board is under the component).
It's at the edge of the board, toward the back of the drive. Mine is
charred and unreadable.
Thanks!
ok
bear
>>I was almost like they were re-inventing Ethernet. :-)
> When Sidhu started on that project ethernet was still pretty nascent.
It was Sidhu, Ron Hochsprung, Larry Kenyon, and Alan Oppenheimer
http://www.patentstorm.us/patents/4689786-fulltext.html
Ron came up with the low-level stuff. He also did the PC Appletalk
card and firmware (and tons of other stuff since then).
Ron also did AppleNet for Lisa.
>
>Subject: RE: Minimal CP-M SBC design
> From: "Barry Watzman" <Watzman at neo.rr.com>
> Date: Sun, 11 May 2008 11:16:18 -0400
> To: <cctech at classiccmp.org>
>
>RE: "1.4 really didn't even do a DISK bios, it was embedded in the bdos.
>the bios for 1.4 was only terminal, punch reader and printer IO. Yes, it
>was a pain to interface any new disk to it."
>
>Allison, that is simply not true. The diskette format (DPH and DBP) was
>imbedded in the BDOS, but the disk I/O was in the BIOS, more or less like
>2.x.
Right and sorta right.
When you get down to it thats nearly as bad. But your right the hardware
was tweekable but the hardware was always assumed to be 8" SSSD in the end.
Being able to easily alter the media dimensions (DPH and DPB) allowed for
larger media and more varied media.
Allison
