If anyone on the list has a user-, or even better, a maintenance manual for a
Bull D120 cartridge drive I would like to hear from them. ( a 10Mb cartridge
drive ca. 1980 )
Spare parts, empty cartridges or a complete replacement part would be more
than welcome.
They will form the basis for a new attempt to bring my ETH Lilith back to
live.....
Jos Dreesen
Hello, I hope no one minds if I post this list of a few important documents
that I think will interest the group, I don't think eBay is the best venue
for them, and I'd rather someone from the group get first shot. Please just
respond back to me directly.
Below, just $5 each plus shipping:
- Netronics 64K S100 Memory Board "JAWS" - approximately 20 pages stapled
with assembly instructions and lots of schematics - no date, maybe 1978ish?
- Solid State Music 2P + 2S I/O Board - approximately 20 pages stapled with
assembly instructions, function check, setup and schematics - 1977.
- Dutronics 8KLST/4KLST Memory Board - approximately 7 pages stapled with
assembly instructions and schematic - no date, maybe 1976ish?
- Dynabyte 32K Memory Board - approximately 12 pages stapled with nice heavy
paper covers, professional inside. Includes general and operating
instructions, memory test program and excellent schematics - 1978.
- Canada Systems CL2400 Real Time Clock - Two manuals; one approximately 12
pages (Assembly Manual - assembly instructions and checkout) stapled with
nice heavy paper cover, and one approximately 6 pages (Appendix - parts list,
schematics) stapled with nice heavy paper cover - 1977.
- Artec Electronics 32K-100 Memory Board - approximately 16 pages stapled
with assembly instructions, parts list, theory of operation and lots of
schematics - 1977.
Below, just $10 each plus shipping:
- Zapple 8K BASIC User's Manual by Technical Design Labs - approximately 25
pages with plastic ring, notebook style binding and heavy paper covers -
1976.
- GraphicAdd Board manual for the VDM and SOL, KEA Micro Design -
approximately 30 pages with nice heavy paper covers, includes assembly
instructions, theory of operations, software package listings (Life
animation!) and schematic, some underlining and writing with some tape on
covers - 1977.
- Cromemco 8K Bytesaver Instruction Manual - approximately 14 pages with very
nice heavy paper covers, stapled at spine. Includes assembly instructions,
parts list, Bytemover software, PROM data and excellent schematic - 1976.
Below, just $15 plus shipping:
- Cromemco DazzleWriter Software - approximately 15 pages stapled with memory
requirements, paper tape loading instructions and assembly and octal listings
- no date, maybe 1976ish?
Thank you, David Greelish
On Nov 24, 10:14, Dave Woodman wrote:
> Let's try to keep this in accordance with real physical laws:- the
> current flowing in the wires will be inversely proportional to the
> resistance since the potential difference across them is the same.
So far, so good...
> The physical principle
> that causes the problem is that the power dissipated is proportional to
the *square* of the current. In case of any doubters -
>
>
> Ohms Law:
> I = V/R
>
> => V=IR
>
> Power dissipated:
> P = IV
>
> => P = I(IR)
>
> So, for example, if one cable/connector pair had twice the resistance of
> another, the second would dissipate four times as much power as the
> first.
Er, no. The current will NOT be the same in each case. If you're going to
use mathematical equations to argue, use the right ones :-)
Power dissipated (assuming steady-state DC):
P = IV
and I = V/R
=> P = V^2/R
So if one cable/connector pair has twice the resistance of the other, the
second will dissipate twice, not four times, the power (since V is the same
for both).
But even that analysis is over-simplified. The PSU provides a fixed
voltage (assuming it's running within expected limits). Part of that
voltage is dropped over the intended load, and part over the
cables/connectors. If the resistance of the cables or connectors goes up
(which is what happened) then the proportion dropped by the cable/connector
combination also rises (and the resistance also goes up slightly as the
temperature rises). This makes the situation slighly worse than my maths
above suggests, but not as bad as Dave suggested.
> If, as other posters have indicated, the bulk of the resistance is in
> the connector then the heating effect will be quite localised, and the
> home cooking lessons are on.
That's still true, of course, but the difference isn't as extreme as you
implied. In the cable looms that failed, it was the cables' insulation
that melted, but mostly near the connectors, and typically on all the 5V
cables, not just the longer ones. I remember some discussions in DECUSERVE
NOTES about it.
--
Pete Peter Turnbull
Network Manager
University of York
Does anybody want one? This is a 300baud serial interface unit.
I've tried it and it works. Slow and noisy, square pixels and all.
In the off-chance that somebody wants this, it's yours for the shipping
>from Tucson, 85711.
As a Canadian, I must explain to our US neighbors that the press
misunderstood the Canadian official at the Prague meetings who was
reported as saying "What a moron" in reference to George Dubya.
In some circles up here there is a slang phrase of approval meaning
"more on top of it", hipper. I'm sure that's what he meant. And of
course Dick Cheyny is also a veritable moron, (in Can. slang terms ,
of course).
Lawrence
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
>No. The wires are connected in parallel. They have different lengths
and thus different resistance >- the longer the higher. "Current allways
uses the way of lowest resistance." So the shortest wire >has to carry a
higher current than the other wires. The wire can carry this higher
current, but the >connector can't. So the _connector_ heats up and "the
magic blue smoke escapes"...
>Solution was to use equal length wires (=equal current distribution
among wires/connectors) and
>better connectors that can carry higher current.
I'll try to stop that late night thinking - it never works :-)
Antonio
In a message dated 11/23/2002 5:13:13 PM Eastern Standard Time,
dlormand(a)aztec.asu.edu writes:
<< Does anybody want one? This is a 300baud serial interface unit.
I've tried it and it works. Slow and noisy, square pixels and all.
In the off-chance that somebody wants this, it's yours for the shipping
from Tucson, 85711. >>
Don't want it, but I remember that being hyped up in the old DAK catalogs.
--
Antique Computer Virtual Museum
www.nothingtodo.org
At 04:20 PM 11/23/02 -0800, Antonio Carlini wrote:
> >only the power harness. And assuming one couldn't find a replacement
>power harness for the bad
> >one, what would it take to modify/repair the bad one to make it safe to
>use? Is it just the matter >of replacing some of the existing wire with
>something of a heavier gauge?
>
>I believe the problem is that the wires are of differing lengths
>and hence resistance. Plus they were (or may have been) specced
>a tad to near the limit. The end result was that the longest wire
>(greatest resistance) heated up the most and eventually went phut,
>leaving the other five (or so) to go pop shortly thereafter.
My experience - having seen several badly melted connectors - was that
the clips on the ends of the orange cable sets don't make adequate
contact with the pins on the backplane and power supply. They heat up
to the point where the connector shell begins to melt, which begins to
oxidize the pins, making more heat due to the additional resistance.
This is not due to different lengths - all the wires in the orange
cable harness are the same lengths.
You can recognize the updated wire harness because it consists of two
white blocks on either end of the assembly; the wires are different colors.
>So heavier gauge and same length would seem to be required.
Nope, it's not the wire that's the problem - it's the connector's
bearing area.
>OTOH if the problem was that bad (none of mine in the lab ever exhibited
>any pyrotechnic tendencies) would it not have corrected itself by now
>:-)
That depends on how much load you put on the cables. Lightly loaded
systems won't ever have a problem.
-Rick
Fred - the PC version was published in '83. I tracked down one of the
authors - Dale Buscaine - and he still has the manual, but has misplaced
the disk! I found one reference that Harv Pennington passed away in the
early '90's. Also found one employee of IJG who lost his personal
TRS-80's when the company folded and its doors were locked. There is a
Michael Shrayer who lives outside of LA, but I haven'r been able to find
an email address for him.
Isn't there anyone out there with a copy?!
Bob Stek
Saver of Lost Sols
At 06:23 PM 11/23/02 -0600, you wrote:
>Anyone know what the official DEC conclusion was?
Sounds like the same problem the the Dec-Rainbow had with it's power
supply, and they had a replacement cable that had thicker wire and better
IDC contacts, but I always went and bought solder type connectors of the
right spacing and appropriate color wire and made my own. the powersupply
and mainboard in the rainbow had the same spacing as video game harnesses
of the same period....
