I've *finally* gotten to putting the stuff online, I just gave up on my
ideals of having a pretty design and actually started doing work :)
I've got disk images from two systems online now, and more to follow as
I find/receive them.
http://www.classiccmp.org/cpm/ should work for that
In a message dated 11/9/2005 1:20:38 PM Central Standard Time,
fireflyst at earthlink.net writes:
Hi,
$50, but I think there are two different vendors who made this part for DEC.
Thanks, Paul
Hi,
I have the logic board, power supply, and what we used to call the "monitor
board" in stock. I worked on a lot of these when I worked for Digital. I now
deal in DEC parts.
Thanks, Paul
Hi Julian,
I have a huge inventory of DEC parts, including VT100 parts if you need any.
Are you in Illinois? I'm in the Champaign area, and can give you some tech
info.
Thanks, Paul
>
>Subject: Re: FPGA VAX update, now DIY TTL computers
> From: Paul Koning <pkoning at equallogic.com>
> Date: Wed, 09 Nov 2005 09:58:19 -0500
> To: cctalk at classiccmp.org
>
>>>>>> "Chuck" == Chuck Guzis <cclist at sydex.com> writes:
>
> Chuck> ... the other was a low-voltage tube
> Chuck> used in automobile receivers that were specified for 12.6
> Chuck> volts on the plate (e.g. 12AE7 dual triode). These would be
> Chuck> coupled with a solid-state driver and power amplifier for a
> Chuck> auto radio with no vibrator supply.
>
> Chuck> ... the second would seem to substantially reduce
> Chuck> the power requirements. To anyone's knowledge were either of
> Chuck> these two components ever used in digital applications?
>
>I doubt it for the 12 volt tube case. For car radios they make sense,
>for the reasons you gave. (I built a radio for our camper using
>those, as a boy scout project. Tubes for the RF/IF stages, a very
>early (1971 or so) op amp as AF preamp, and totem pole transistor AF
>final amp.)
This is somewhat off topic. To directly answer it however...
The additional components of the power supply (vibrator or transistor driven)
are overhead and high drain even for auto use as efficientcy is at best 80%.
12V plate voltage car radio tubes were a considerable savings in drain by
deleting the HV supply. The heater power required for the 12V vs the more
usual high voltage cousins is the same or only slightly higher, some cases
it was lower depends on the specific tube. the real difference was
generating the HV had a standing 10W load that the tubes maybe used
less than 70% of.
>
>But I don't think the electrical parameters were all that good, given
>the unusually low anode voltage. And I don't see any reason for the
>power consumption to be less. Lower voltage, sure, but the current
>may go up in proportion. And the filaments were still the usual,
>which accounts for a fair chunk of the power.
Correct. The transconductance is lower and the lower max plate current
means lower power and overload thresholds. For computers that also
translates to slower switching speeds. For AM car radio use it's
acceptable but for higher performing radios it really is problematic.
The serious limitation for tubes has always been the heat and power
>from the filament rather than the heat and power used for functional
circuits. Computers suffered using them as heat removal and protecting
other components from that heat were the issues. Never minding even with
135A 6.3V filiments used in the subminis say two hundred of them is a
mere 27.A @ 6.3V or 162W of power and no small issue with bussing around
that kind of power. when you consider they may run at 100V on the plate
and maybe 2ma (.2W) and that same 200 (assuming all conducting the same)
is only 40W power dissapated. It's the heaters that are at issue.
Transistor systems removed the heater power and lowered the per device
dissapated power by a typical factor of 5 so 200 transistors were running
in the 8-10W range. The latter is important as now heat is less an issue
and power distribution simplified. With heat being less an issue more
compact and modular systems are easier to design and assemble.
After transistors the second evolution in computers was packaging.
Allison
Does anyone have a DEC VR201 monitor and/or LK201-AA keyboard they'd
like to sell? It would be great if I could find one in the NH/MA area
so that I can pick it up. The monitor could be kind of expensive to
ship. I need these for a DECmate III+. I don't need the word
processing keyboard as I expect to use this machine to run OS/278.
Thanks,
David Betz
>
>Subject: Re: FPGA VAX update, now DIY TTL computers
> From: "Chuck Guzis" <cclist at sydex.com>
> Date: Wed, 09 Nov 2005 09:46:07 -0800
> To: cctalk at classiccmp.org
>
>On 11/9/2005 at 10:46 AM Allison wrote:
>
>>The serious limitation for tubes has always been the heat and power
>>from the filament rather than the heat and power used for functional
>>circuits.
>
>So whatever happened to tunnel cathodes? It was a very hot topic in the
>60's.
Not much after that. An idea that came too late in the game.
If anything there were more unique designs in the gated beam, sheet beam
and segmented cathode (power tubes) that evolved.
Allison
>
>Subject: Re: FPGA VAX update, now DIY TTL computers
> From: "Chuck Guzis" <cclist at sydex.com>
> Date: Wed, 09 Nov 2005 09:37:02 -0800
> To: cctalk at classiccmp.org
>
>On 11/9/2005 at 11:49 AM Allison wrote:
>
>>True for later generations. However CDC6000 was more specialized
>>packaging where the PDP6 was a whole lot of flipchips and limited
>>specialized packaging.
>
>Automated wire-wrapping is less expensive than other methods, but doesn't
>give one the leve of control that other methods afford.
depends on what your trying to control. Costs would be one dimension. ;)
>It now seems incredible on what amounts to a 10 MHz mainframe, but wire
>length was a big part of the CDC 6600 design puzzle. I recall a friend
>telling me that his first assignment on his job at CDC was to take Cray's
>6600 prototype and measure each coil of twisted pair to which had been
>attached a tag that said "tune" in preparation for actually manufacturing
>the thing.
Not to confuse propagation delay with with clock rate. It's important
as any of those delays could be critical path. However areas like ALU
and memory were often the bottleneck.
> The old 6000-series taper-pin backplanes were a deep maze of wiring
>hanging here and there and the nanosecond-per-foot rule was an important
>part of the 6600 design. CDC continued to use taper-pin style backplanes
>long after other firms were using machine-wrapped backplanes, mostly, I
>suspect because of the ability to optimize propogation delays--and still
>retain the use of standardized "cordwood" logic modules.
>
>Cheers,
>Chuck
Every manufacturer seems to have their own favorite technology for
packaging and interconnecting. Even for packaging there are more
generations that appeared. Another example was DCC D112 a TTL
PDP-8 but with a very differnt form factor and packaging. It
however was not the first. I think it was CDC160(I should check)
that helped to start that many years before.
Allison
>
>Subject: Re: MSCP SCSI controller speed
> From: Paul Koning <pkoning at equallogic.com>
> Date: Wed, 09 Nov 2005 11:22:02 -0500
> To: cctalk at classiccmp.org
>
> Allison> You need a real time or single user os to get better
> Allison> results. Plain old dos might do far better or maybe a
> Allison> custom kernal tuned for this use.
>
>All you need is an application, or OS, that can queue up multiple
>transfers. I thought the buffered I/O in Unix would take care of
>that.
>
>Certainly if you do single I/Os and wait for the answer each time,
>things will be slow, but the OS isn't really at fault then.
>
> paul
True. However a RT OS has better known and predictable latency.
There is also the issue of OS overhead for process control.
Another way this could be improved even in the Netbsd case is to
implement LRU caching so that when the IO request appears the need
to hit the device for a transfer is defered. If the buffer is large
the likelyhood of a cache hit is high and the idel time process can
be writeback and read ahead.
Allison
>
>Subject: Re: FPGA VAX update, now DIY TTL computers
> From: woodelf <bfranchuk at jetnet.ab.ca>
> Date: Wed, 09 Nov 2005 09:12:28 -0700
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Allison wrote:
>
>>After transistors the second evolution in computers was packaging.
>>
>>
>>
>No, I think Automatic wire wrapping was the big difference untill the 70's.
>Then it was the dip packaging of the transistors in the form of SSI and
>MSI.
They were later and significant however, Go back and study TX2 (Lincoln labs
Clark, Olsen, Best and Mitchell ca1956). Their inovation was packaging
into modules of standardized circuit (chips would shrink this) modules and
then integrating them into modular subsystems (ALU, memory and IO). There
were also logical enhancements on the archetecture level as well.
The lessons of the TX2 were applied directly to DEC logic modules that
would evolve to FlipChips.
Automatic wire wraping and IC were the next and nearly concurrent waves
and served to greatly lower cost. By then we were well into the 60s.
Allison
