With his express permission, I'm forwarding a mail from a public list.
I am interested in Gene's comments about the design of SCSI, but I
don't know enough electronics to judge.
I thought others here might.
I have trimmed the mail a little to the relevant parts.
--
Liam Proven - Profile: https://about.me/liamproven
Email: lproven at cix.co.uk - Google Mail/Hangouts/Plus: lproven at gmail.com
Twitter/Facebook/Flickr: lproven - Skype/LinkedIn: liamproven
UK: +44 7939-087884 - ?R (+ WhatsApp/Telegram/Signal): +420 702 829 053
---------- Forwarded message ---------
From: Gene Heskett <gheskett at shentel.net>
Date: Wed, 8 Jan 2020 at 17:29
Subject: Re: External Disk Intrusion
To: <ubuntu-users at lists.ubuntu.com>
On Wednesday 08 January 2020 09:01:35 Liam Proven wrote:
[...]
> The thing is that actual SCSI cabling faults are very hard to
> diagnose. We used to have internet jokes about them and the need for
> sacrificial goats or chickens, but of particular colours for different
> cable types, pentagram drawn in blood, holy candles, etc.
>
And all that pickityness can be laid at the feet of a bean counter
between the interface card designer, who specified a $2.00 schotkey
diode for buss isolation, which had a maximum voltage drop across it of
perhaps .1 volts, and changed to have an 8 cent Si diode with .666 volts
drop across it, thereby lowering the logic one voltage by .45 volts.
Since the logic one at the logic chips inputs had to be at lease 2.2
volts, and the nearest set of termination resistors gave 3.0 volts when
this buss isolation diode was replaced with a short, but with the cheap
Si diode in there gave a logic one voltage closer to 2.4 most of the
circuits noise margin was used up and considering that same bean counter
crossed out the 5% terminators in favor of 20% tolerance, the result was
predictable.
The situation was much better when active terminations came into use, but
by that time the scsi buss's reputation was doomed.
But back in the day of the bottom 190 market tv stations were generating
their on air gfx needs with a bank of Amiga computers, every scsi card
that came in the door, if the engineer was worth his paycheck, that
diode was replaced the first time the Amiga it was in, crashed. End of
problem except for one Trump Card, where in traceing that card, I found
the termpacks had been soldered in bass ackwards. It was easier to cut
and jumper the supplies traces than to unsolder the packs and turn them
around. So I did that in addition to swapping out the infamous diode.
We, in a middle 160's market, were the first to put our news on the air,
out as a webpage, which led to legal problems because CBS fussed about
their copyrights, so we had to filter any web content that came from
CBS, but that didn't last long after their bean counters discovered
there was money to be made. That was all driven by ARexx and delivered
by dialup from that Amiga in those Jurrasic (in web time) days.
Who am I to criticise the makers of that stuff? I have an 8th grade
diploma, but I am also a CET. Look that up if you care.
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
--
ubuntu-users mailing list
ubuntu-users at lists.ubuntu.com
Modify settings or unsubscribe at:
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Mike -
Cer-Comp
5566 Ricochet Avenue
Las Vegas, NV 89110
(702) 452-0632
William E. Vergona wrote firmware on those two (2), 2708 ROMs.
He later (1980s) worked with Tandy (Coco-3) Color Computer products.
==
?68 Journal, May 1980 (Back to Future, 40 years later)
MiniDisk+ DOS , Pages 11 - 13
http://www.swtpcemu.com/swtpc/68MJArchive/V02N05_May1980.pdf
Have you contacted Bob Applegate (Corsham Tech)?
https://www.corshamtech.com/ss-50-faqs/
He might be aware of source from his SS-50 clients and contacts.
Bob reopened his business (Corsham) three weeks ago, for a period of time.
I did not see him at VCF Midwest, due to his health issues.
https://www.corshamtech.com/back-in-business-for-now/
Greg
Chicago
==
From: Mike Douglas <deramp5113 at yahoo.com>
To: cctalk at classiccmp.org
Subject: SWTPC 6800 and Percom Floppy Controller
I?m restoring a SWTPC 6800 that includes the Percom LFD-400 floppy controller. This controller goes on the SS-50 bus instead of the SS-30 bus where the SWTPC controllers installed. The standard Percom MiniDOS PROM is installed, and the other two PROM sockets have a third party extension called ?Minidisk+?. This was made by a company called Cer-Comp. These PROMs are instead of Percom?s own ?MiniDOS PlusX (MPX) PROM.
I?ve got the system working, and I can use Minidisk+ to save and load files, but I know I?m missing some nuances of command parameters. I don?t have any sort of documentation for Minidisk+, so before I go figure it out by disassembling the PROMs, does anyone have any sort of documentation for Minidisk+ by Cer-Comp for the Percom LFD-400 floppy disk controller?
Also, I?d like to burn the MPX PROM as an option. Does anyone have the MPX PROM or the source code for MiniDOS PlusX?
Mike
On Fri, 2020-01-03 at 12:00 -0600, cctalk-request at classiccmp.org wrote:
> On 1/2/2020 1:35 PM, Cameron Kaiser via cctalk wrote:
> > > > Anyone done anything with Netware *for PowerPC*? Allegedly
> > > > there was
> > > > some attempt at Apple to put it on what later became the
> > > > Network Servers
> > > > (the codename was apparently "Wormhole").
> > > I know the people who were working in it (based on Portable
> > > NetWare)
> > > AFAIK it never shipped.
> > Was this based on the Cygnus PowerPC port, or was it Apple-
> > specific?
> >
> Sun did a power? PC? port I think paid for by IBM, which would have
> run
> on both the open Apple servers that briefly existed, and on IBM PPC
> systems.
>
> A lot of odd PPC work happened in a group a friend worked for in
> Austin
> TX, but not sure if they did Netware work there.? There was a lot of
> OS2
> work there as well, but that's off track a bit more.
>
> thanks
> Jim
I was lead tech at a small computer company in Asheville, NC. in those
days. I ran OS/2 from version 2 in the early 90's to Ecomstation in
the early 2000's.
Does Talingent Pink sound familiar? OS/2 was ported to powerPC, and so
was Netware iirc. The field was quite busy with hopeful Microsoft
killers. OS/2 was to be morphed into a cross-platform o/s, to wean
folks from dos/x86..... Then PPC kills the x86 and we all get a decent
os. That was the plan anyway. I never saw OS2 for PPC or Netware for
OS/2, thought I know both to have shipped.
Jeff
Hi all,
I snagged one of these Nixie-like displays (from a calculator I assume) and
I'd like to light it up. Does anyone know where I might find the datasheet
for it? Google hasn't turned up anything.
https://www.ebay.com/itm/264110638970
Any help is appreciated!
--
Anders Nelson
+1 (517) 775-6129
www.erogear.com
Bitsavers has a schematic of the ANSI interface version of the Priam
3450/7050 eight-inch hard drives, but does anyone happen to have the
schematics of the "normal" version (Priam interface, as opposed to SMD or
ANSI)?
Hello all, a new member here.
I?m in the UK where I?ve lived for 17 years now. Before that I lived in
Canada.
I got my computer bug as a kid playing with VIC20, TRS-80, APPLE ][ and a
mainframe. Presently I work as a .Net programmer mainly doing ASP.Net. Most
of the old hardware I had stopped working for one reason or another and was
binned ? my Dad didn?t like clutter. So I?m surrounded by laptops and a
couple of older machines which used to run the network in the office.
I?ve started looking around for some vintage machines that I used at Uni.
Sparcstation, NeXT Cube are the ones I used the most.
One machine that I would very much like to have is a SUN Sparcstation as
I?ve some old projects that I did at university which I?d like to carry on
working on (also to show my kids what I did at Uni) If anyone on here is in
the UK and has a Sparcstation 1,2,4,5 I?d be interested. If it has the ??
drive than I?d be interested in that too. SunOS would be OK as that?s what I
used. I am tempted in a NeXT but my project used X11 and a library called
InterViews which I think will only work on X. Maybe someone can clarify
that.
Anyway, enjoying reading the posts and happy to have found you.
Salik.
I just listed one of my TU55s on eBay
I have a second one available in a rack with a TC01 avalilable for pickup in Fremont, CA
that I'm accepting offers on.
I'll be in Chicago for a week soon for a work event. Limited time for
myself but I'll have some time Sunday to maybe Uber around. Any suggestions
or cool spots for a computer collector to hit?
I see a museum of broadcast communications is close to where I'll be which
may be neat. Not sure if there are any used stores that might have vintage
computers but always willing to try.
