<> > Hmm... Unix came out first on a PDP7, but later versions ran on the
<> > PDP11. I am not sure where C came in all this, but there are certainly
<> > PDP11 versions.
<>
<> > I've never heard of either fitting on a PDP8.
While neither were developed on a pdp8 there is nothing to say it cant be
done. The -8 does run fortran, basic, cobal, focal and I believe pascal as
well.
The reson it wasn't done (C or unix) is timing. the -8 was past it's peak
and the PDP-11 had eclipsed it.
Allison
I doubt that there's need for the high voltage drivers. Any open collector
should work if your LED's are driven from the 5V supply.
Be careful with your socket, i.e. make sure things will fit back together
before you solder it in!
Dick
-----Original Message-----
From: Bill Sudbrink <bill(a)chipware.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Wednesday, June 30, 1999 3:20 PM
Subject: IMSAI front panel (7405 == 7406)??
>I'm suspicious of one of the 7405s (Hex open-collector
>inverters) driving the data lines to the MPU-A. I
>don't have any replacements, but I do have a handfull
>of 7406s (Hex open-collector high-voltage inverters).
>The pinouts in the Chip Directory look the same, only
>difference by them is that the 7406 is "Maximum output
>voltage is 30V". I think I'll try socketing the
>suspect chip (U1 for anybody keeping score) and putting
>in a 7406.
>
You may indeed be onto something here, Allison, but the ISA is no less
general in its inherent qualities than the S-100, and I'd submit that a
major case for the S-100's popularity for non-8080 applications was the
ready commmmercial availability of numerous desirable functions at
reasonable prices. That's how the ISA occurred to me.
Aside from that, a general purpose not processor-biased architecture would
provide a few control signals, e.g. IORD, IOWR, MEMRD, MEMWR, maybe a couple
of clocks, probably one fairly fast one suitable as a dot clock for a video
circuit, and one slower, suitable for bus transaction timing, a few
interrupt and DMA support signals, and a couple of dozen address lines.
Parity and maybe a "tilt" line would be handy, as well as a wait signal.
Most busses have these signals in one form or another.
The key element for generalized development, though, is whether or not you
can afford to buy the functions you don't want to build right away. Don't
you agree?
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, July 03, 1999 9:35 AM
Subject: Re: OT: A call to arms (sort of)
><agree on what your goals are? Some of these suggestions indicate that
><certain people like certain things, but there's really been no discussion
o
><why one might want to use one or another. In the absence of
><goals/requirements, there can be no analysis or design.
><
><Does anybody know where this is supposed to lead?
>
>To yet another iteration of the last 30 years of computer and bus design.
>
<snip>
>
>The ugly exception! This doesn't make it good, only the odd exception
>for unexplainable reasons despite being primarily a 8080 bus!
>
>S100 8080, 8085, 808x, 80x86, z80, z180, LSI-11, AM100, TI9900, 6502,
> 6800, 6809, 6800x
>
>How is it that one of the ugly busses stands out like this in history?
>My cut is that the very flavor of an experimentors "hobby" bus was the
>draw.
>
>Allison
>
The 7109 is an adc, of the dual-slope integrating variety more or less like
the panel meter IC's Intersil developed and everyone else copied. I think
www.maxim-ic.com is the place to look for the functions on this board. I'll
let you guess what the DAC800 is. (chuckle) If it's working, it's probably
a keeper. Look for any additional identifiers and then hit the web with a
search for that.
Dick
-----Original Message-----
From: Joe <rigdonj(a)intellistar.net>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, June 07, 1999 8:38 PM
Subject: ID this PC card
>Hi,
>
> I picked up an old IBM AT the other day and found a strange card in it.
>It's a full length card with an 8 bit ISA plug. It has two Burr Brown
>DAC800P-CBI-V ( D to A?) ICs on it along with a large IC marked TSC
>7109CPL. (I have no idea what that one is.) There is also a small flat
>sealed Yuasa NiCad battery in the top corner of the card. It has 37 pin
>male connector on the back and it's marked "copyright 1983 MBC". Most of
>the ICs are dated 1986. It looks like it may be some kind of D to A
>convertor card. Does anyone know what it is for sure?
>
> Joe
>
>
>
<agree on what your goals are? Some of these suggestions indicate that
<certain people like certain things, but there's really been no discussion o
<why one might want to use one or another. In the absence of
<goals/requirements, there can be no analysis or design.
<
<Does anybody know where this is supposed to lead?
To yet another iteration of the last 30 years of computer and bus design.
To me it's mostly an exercise, few are into construction of their own
design and fewer still actually have the resources to do it. Those that
can aren't going to let a committe design their box (they do that at work).
so whats left... A discussion of buses and what was good or bad about each
one.
FYI: the greatest common problem of most buses is they tend to be somewhat
processor centric. To wit.
Multibus 8080, 8085, 808x, z80 mostly
STD Z80
VME 68K
Qbus PDP-11 or VAX
Unibus PDP-11 or VAX
SS50 6800 and 6809
The ugly exception! This doesn't make it good, only the odd exception
for unexplainable reasons despite being primarily a 8080 bus!
S100 8080, 8085, 808x, 80x86, z80, z180, LSI-11, AM100, TI9900, 6502,
6800, 6809, 6800x
How is it that one of the ugly busses stands out like this in history?
My cut is that the very flavor of an experimentors "hobby" bus was the
draw.
Allison
<Dwight, exactly, I forgot to say that I'm PULLING air from heat
<producing components via shrouds around heatsinks and ducts to draw
<out hot air from cards and PSU. Like vacuuming up hot air and keep
<it seperated from cooler air till exhausted outside.
Also most fans do not work well against any pressure, the airflow drops
greatly!
A small blower in the 15-50 cfm range will cost more than a fan but not
so much as to prevent attaining the goal of reliability via effective
cooling.
Allison
<> 2. The only way to make uniform air flow is with restriction.
<
<In other words: ducts and shrounds?
Thats it and ample power to motovate the air.
<Tell me about this "rotating air will do strange thing till
<straightened out" what it do strange thing? And how is done to
<straighten it out?
Air does not go through a fan smoothly and the rotation of the fan
plus aerodynamic effects imparts a spin on the air. That air will
not travel nicely.
<Do tell your tales about this! I'm trying to design a case to do
<cooling of all drives, PSU motherboard and CPU by one large quiet
<fan and ducts/shrounds. Isssues: noise and reliablity from too many
<fans.
Harder tha it looks as each drive has a differnt fit and different
air flow. Plan to use a big blower rather than a fan. Also air at
higher pressure can transport more heat so a 200cfm imparting a static
pressure of and inch of water along with airflow will cool better.
IT will also be noisy!
Allison
< Actually air flow is quite complicated. Using muffin type fans
<makes it worse. Here are some basic rules of thumb.
Yep!
<1. Fast moving air in an open space will find a surface
< and run along it.
Pressure boundary.
<2. The only way to make uniform air flow is with restriction.
Also a must as you cannot control freely moving air.
<3. Rotating air will do strange things until straightened
< out. ( examples, air coming from a rotary fan and also
< most air going through a single small restriction ).
Vanes unrotate air.
<4. Laminar flow is best understood but turbulent
< flow removes more heat.
The trick is to get turbulent air that goes where you want it.
< I have seen the above problems cause all kinds of effects
<that were not obvious at first.
The best case I know is the 8xxx and 9xxx series VAXes as they were air
cooled and also tried to be quiet and efficient in cooling the contents.
Both series would cook in minutes if the cooling failed (or if the phase
rotation was wrong!).
The Altair cooling was poor at best even with a 125CFM fan (noisy too).
the IMSAI was a bit better, the compupros s110 rack better still. The
best s100 crate was the Intergrand and TEI boxes as they clearly were built
to address the heat problem. An example of how rough this is the NS*
horizon I have has a 115cfm fan with a filter pushing air in and the box
has varios strips of manilla (144pound stock) to block and route the air
or the heat build up on the teltek HD controller and the z80 master
processors (z80, 64k sram, 2sio and ttl mapping and bus master logic)
would make them shut down even with a modified PS.
Allison
Anyone know what a ImageMaker Model IM100 by Presentation Technologies is ??
Saw one today at the thrift for $25 but would not buy since it was unknown
to me and was a little high in price. Thanks John
