There were PLL devices I played with back then, e.g. Signetics 564, among
others, which boasted 50 MHz operation, but standard TTL logic was spec'd at
20-25 MHz at the top end, frequency wise, and one had to use H-TTL or S-TTL
to make your circuitry remain within specified limits. If you weren't into
worst-case analysis, you might get away with operating a circuit outside
those limits more often than not, but while the cases that worked might on
occasion get you some praise or a bonus, the ones that didn't would
absolutely get you fired. Back in those days, although the S-TTL ran some
50-75% faster, it cost well over double, if the function you needed was
available. It often required that several parts be replaced with schottky
parts to avoid races, as synchronous design was not yet as popular as it is
today, and synchronous circuitry has to have everybody synchronized with the
same clock, hence, able to function at the schottky rate which increased the
cost even more.
I'll stick with my earlier complaint, that the most annoying problems I saw
back then were unconnected inputs and races, both of which became VERY
troublesome when a substitution of either LS or, worse, HCMOS parts was made
as the product matured. Often this required extensive redesign, frequently
with the addition of pipeline registers to synchronize asynchronous events,
which made for ugly reworks.
Dick
-----Original Message-----
From: Allison J Parent <allisonp(a)world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, March 20, 1999 4:02 PM
Subject: Re: Fw: Pre-history of Digital Research
><designs of yesteryear. Back then we were still learning about race
><conditions and setup and hold time violations, and the like. Back then, a
><circuit designed to operate from a 25 MHz clock was taxing the limits of
th
><technology, while today, people don't even blink when the clocks are over
1
><times that fast.
>
>While the parts werent fast and there were things to be aware of it wasn't
>that backward. There were however sloppy designers doing sloppy designs.
>
>I did a PLL design, direct counting to 50mhz in 1973, that was near the
>TTL upper limit but not that hard to do. Doing 25mhz plus logic in 1975
>was not unheard of and Mini makers were doing it but there were economic
>issues in doing that not technical.
>
>The most common errors were lousy board layouts and weak ground planes.
>the altair suffered from both severely. Another fault was many designers
>were forgetting that backplanes and other busses were trnasmisstion lines
>and needed to be terminated properly, again the altair was the worst going
>from the front pannel to the bus with a bundle of wires the shortest near
>6 inches long. Even at 2MHz this was sloppy practice. Looking at
>contemporary DEC and DG backplanes for the time it was clear the design
>techniques were known.
>
>Don't forget in 1989 (-10y) a PC running at 25mhz was the hottest thing
>going. It would take another decade to get from 25 to 250+ as a mator of
>routine for PCs but there were system going much faster than PCs in 1989.
>
>
>Allison
>
I'm not so sure you're as far off-topic as you think. The connectors you
mentioned were all "old" technology back in the mid '70's when MITS and
IMSAI were pups. I'd submit that the DIN41612 connectors as used in VME bus
cards and in Apple Macintosh's NuBus are inexpensive enough today that your
can afford them. They're also 20 years old, as I was including them with my
VME wire-wrap boards in 1981-82. IIRC, the first run (20 boards) cost about
$19 per board for the connectors and mounting hardware. That's not much
more than the then-popular S-100's would have cost for 2 of each gender.
The notion of a front panel has often intrigued me, but recently I've
thought of using it more as a bus monitor probe, perhaps with an ethernet
connection to a PC and used for diagnosing functional anomalies. Instead of
discrete logic, it would use one or two of the SCENIX -SX processors and
drive the bus directly, loading memory and I/O features and storing the
monitored information in local memory for transmission to the PC host.
information could be displayed more effectively at the PC, but immediate
readouts in the form of discrete LED's, bit for bit, could be driven as
could HEX displays. The part I would view as important, however, is the
diagnostic function.
As for your loadable control store, I'd suggest you consider a mid-sized
FPGA. These can be loaded from a local processor and the architecture
changed at will, by reloading the device to suit the desired architecture.
if pinouts don't work, there are electrically reprogrammable crosspoint
switches routinely used every day, e.g. Lattice' GSX devices, to correct
unresolved routing problems, and there you are. You could actually fashion
your own processor right on your desk, but that really is off-topic.
Dick
-----Original Message-----
From: Chuck McManis <cmcmanis(a)mcmanis.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, March 20, 1999 4:18 PM
Subject: "new" classics (was Re: Pre-history of Digital Research)
>About every three weeks or so I kick around this idea of building a "new"
>classic computer. Lately my thoughts have been to build something with a
>loadable control store so that I could microprogram different instructions
>as I saw fit or was necessary. Of course the machine would have a front
>panel with switches and LEDs to indicate state.
>
>I then come to the question of "add in" boards. Ideally one would like to
>establish some sort of bus and make available a wide variety of add in
>boards that could be used to customize the system.
>
>Then there is cost, one would like to keep the cost at a minimum as well.
>
>So in the connector area I've been considering something "VME" like which
>would consist of two 50 pin right angle molex connectors and the
>"mainboard" would consist of 50 pin AMP sockets. These are pretty cheap
>because of SCSI and they should provide enough pins. (one could imagine
>three connectors for a total of 150 pins but that seems like overkill.)
>
>Unfortunately I think this is way off topic for this group.
>--Chuck
>
>
<designs of yesteryear. Back then we were still learning about race
<conditions and setup and hold time violations, and the like. Back then, a
<circuit designed to operate from a 25 MHz clock was taxing the limits of th
<technology, while today, people don't even blink when the clocks are over 1
<times that fast.
While the parts werent fast and there were things to be aware of it wasn't
that backward. There were however sloppy designers doing sloppy designs.
I did a PLL design, direct counting to 50mhz in 1973, that was near the
TTL upper limit but not that hard to do. Doing 25mhz plus logic in 1975
was not unheard of and Mini makers were doing it but there were economic
issues in doing that not technical.
The most common errors were lousy board layouts and weak ground planes.
the altair suffered from both severly. Another fault was many designers
were forgetting that backplanes and other busses were trnasmisstion lines
and needed to be terminated properly, again the altair was the worst going
>from the front pannel to the bus with a bundle of wires the shortest near
6 inches long. Even at 2MHz this was sloppy practice. Looking at
contemporary DEC and DG backplanes for the time it was clear the design
techniques were known.
Don't forget in 1989 (-10y) a PC running at 25mhz was the hottest thing
going. It would take another decade to get from 25 to 250+ as a mator of
routine for PCs but there were system going much faster than PCs in 1989.
Allison
That's truer today than it was 20-25 years ago. Much of what we saw on
S-100 equipment was used not because, say a J-K flipflop pair was the best
choice of devices, but because the boss had just bought a barrel full of the
things as surplus and wanted them used.
My concern in the previous post was over the performance of presently
available components in old circuit boards. First, because they were often
designed with the performance of the devices used figured into the timing
equations, and secondly, because it no longer works to leave device inputs
unconnected as was frequently the practice in the mid-late (Pre-LSTTL,
Pre-HCMOS) -70's.
Dick
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, March 20, 1999 3:45 PM
Subject: Re: Fw: Pre-history of Digital Research
>>
>> I've got to disagree on this one. From what I've observed the 100-pin
>> card-edge connectors are pretty common. I really don't know why, but
they
>> are. Every time I look at the local surplus parts house, I see those old
>> connectors, in the same box they were in 20 years ago, even though the
store
>
>Sure, but you can't design something, certainly not something that's
>going into production, based on parts you find in a surplus shop.
>
>You need to use parts that are in current production IMHO. I won't even
>do one-off designs based on parts I've found surplus. I don't know I'll
>be able to get parts to maintain it in the future.
>
>
>> on the secondary connector for Multibus-I, nor do they often have the
>> 31-pair or 18-pair connectors used on a PC backplane. Now, I didn't say
I
>
>Odd... Those are available _new_ in the UK without much problem...
>
>Does anyone know of a source (UK prefereably) of 0.125" 44 pin doublesided
>(22 pins on each side) connectors. No, I don't mean 0.156" ones. I
>believe they fit the expansion connector on the HP9100, for example.
>
>-tony
>
Stopped by the thrift store today and grabbed a handful of books. I
don't have use for these so if anyone wants them, let me know. I'd like
to get $1.oo plus postage for each of them. All are softcover in very
good condition.
128 Internals - The Authoritative insiders' guide. 1985 Abacus
software. Softcover 500 pages. This looks like a *great* resource for
anyone interested in the COMMODORE 128.
A Practical Guide to the TANDY 1000SX. Radio Shack, Spiral Bound, 350
ppg. This is the original manual that came with the system.
WORDSTAR Made Easy - Osborne / McGraw Hill 1982, 160 PPG. A baisc users
guide to the word processor.
First Come, First Serve --- Steve Robertson <steverob(a)hotoffice.com>
Hello, all:
Well, it seems that my deal for a bunch of AIMs is finally coming
through. I should have two extras available within the next two weeks from I
guy that I know in NJ. Cost: $100 + S/H.
Anyone interested should contact me off-list. Sorry, US shipments only.
[ Rich Cini/WUGNET
[ ClubWin!/CW7
[ MCP Windows 95/Windows Networking
[ Collector of "classic" computers
[ http://highgate.comm.sfu.ca/~rcini/classiccmp/
[ http://highgate.comm.sfu.ca/~rcini/pdp11/
<---------------------------- reply separator
I hooked up an decwriter III that hasnt been used in over 10 years. When I
turn on teh power, every LED lights up, and the 4 digit display lights up
to all 8's. The printhead doesnt return to the left.
Any suggestions?
-Lawrence LeMay
On Mar 19, 16:29, Dean Billing wrote:
> Subject: Western Digital PASCAL microengine / p-system.
> I have also been scanning all of the WEB sights that have information
about
> UCSD PASCAL and obsolete and disappeared computers and I find no
reference
> to Sage Computer Technology of Reno, NV. They made the Sage II/IV
systems
> that came with UCSD PASCAL installed. They were M-68000 based systems
and
> probably ran other operating systems too. Anybody remember them?
If you mean what I think, I have two of them (Sage-II's). A Sage-II is a
cream-coloured box with dark grey front and rear panels.
Once upon a midnight dreary, Sellam Ismail had spoken clearly:
>On Fri, 19 Mar 1999, Aaron Christopher Finney wrote:
>> I don't have much time at all, but have a lot of experience with web
>> programming and would definitely donate whatever time and energy I could
>> to something like this, if someone wanted to actually organise a
>> project...
>This is exactly the type of trading board that I've been meaning to add
>to the VCF web site for aeons now. If you can provide the programming
>I'll certainly host it. Its definitely a needed service.
[snip]
Hey! Hey! Hey! Yes, this is a *shameless* plug, but try this place:
http://www.the-dock.com/club100.html
and click on either the For Sale, Wanted or GuestBook...
(It's an ontopic site - Model 100/102/200's...)
And.... I wrote the programs that do that. It's simple, it's basic, but
hey... it works! And... it's free, too! And... it's written in Perl, so it
can run under most any operating system. And... And... Darn, ran out of
Ginzu Knives... Oh well! ;^>
If anyone wants the code, just zing me a private email...
Thanks,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger --- sysadmin, Iceberg Computers
Recycling is good, right??? Ok, so I'll recycle an old .sig.
If at first you don't succeed, nuclear warhead
disarmament should *not* be your first career choice.
<I do know that my PENTIUM HAS THREE TYPES OF COMPUTERS IT CAN BE SET UP
<AS 1. DESK TOP, 2.NETWORK SERVER(in my opinion not a good choice) 3. I
<can't remember right now as I am on my 486 @ my girlfriends. If Jason is
Generally and based on experience with 35 desktop W95 sytems and 3 NT
servers as an internal (only) intranet.
W95 has minimal security and is difficult to make hard for security.
Suitable as webserver in a non hostile environment not requiring security
>from malicious users.
Win NT can be secure, but watch those service packs as some improve it and a
few reduce it (bugs!). Generally fairly secure, common enough in use that
security holes are well known and publicized.
I'm currently looking at linux, it has potential.
Another I do know well is VMS as its generally very secure and made very
secure. It also has security by obscurity, most PC heads haven't a clue want
a VAX(alpha) or VMS is.
Allison
