-------------- Original message from ard at p850ug1.demon.co.uk (Tony Duell): --------------
> > I know the design well. The contacts spring togethe, and are kept apart
> by a plastic pin in the plunger when the key is not pressed.
>
> The keycap is a press-fit into the plunger, which means it slightly
> stretches the latter. In time the plunger cracks anyway, even if you
> don'y drop anything on it.
>
> The other prolem is fitting new contacts. At one time you could buy
> individual contacts and more importantly a tool to hold them and press
> them in place without damaging them. Said tool was (at least) sold by
> Radio Shack Nationl Parts Centre and HP (I have part numbers for both),
> but AFAIK it's now unavailale, It's possilble to use long-nose pliers
> carefully, but it's very easy to mangle the contacts.
>
> >
> > What I would like to find is a doner type of system that does not have
> > any value so I can rob the middle piece.. (typewiter) ???
>
> I've seen this type of keyswitch on (at least) the following :
>
> DEC VT50 series
> DEC VT100 series
> TRS-80 Model 1 (early version only)
> TI 99/4a
> HP80 series (HP85, etc)
> HP9915 keyboard (very rare!)
> HP98203 (small keyboard for the HP9816)
> HP2623 (IIRC) graphics terminal
>
> Unfortunatley none of those are exactly common. When I repaired my 9816,
> I was lucky enough to find a 'spare' VT52 keyboard PCB i nthe junk box,
> given to me with a load of other DEC spares, which provided contacts,
> plungers, even keycaps.
>
> -tony
>
Yes that is what I'm finding . The donors have more value than the
pieces I'm working on.
Tony, Do you have one of these tools ??? and/or what it looks like
- Jerry
Jerry wright
g-wright at att.net
I have a couple of Macintosh Color Classics I'd like to find a home
for. As far as I know, they both work. One has been upgraded with a
faster system board and one has a IIe card in it. I also have the
cable and external 5.25" drive to go with the IIe card. Both machines
come with a keyboard and mouse.
The catch is, I'm not really interested in packing and shipping them.
I'd first like to see if anyone is willing to come pick them up. I'm
in Bedford, NH 03110 and would be willing to drive a bit to meet
someone if that is necessary.
Anyone interested?
David Betz
Looking for an Western Digital WD1001 MFM controller card , preferably working.
It is an 8X305 based, very early controller card .
I do not know how rare they were, but they are bound to be rare now.
Jos Dreesen
From: dwight elvey <dkelvey at hotmail.com>
> More voltage and it would have used more power. Less
> voltage and it would have been too slow. In the DTL days,
> unlike today, the major factor in speed was the transistors
> them selves and not the interconnect. Today, the interconnect
> dominates and the smaller one can make the transistors,
> the shorter the interconnects.
I've got a brief Moto app note here from the late 60's that
essentially says that 7400/5400 TTL could be run from Vcc as high as
+7, so long as V(IH) was not allowed to go any higher than +5. The
term "exceptional circumstances" is used, meaning, I suppose, where
better noise immunity or more speed is required.
Since this is contemporary with 5400/7400 SSI, I don't know if it
could be carried over to more recent MSI/LSI TTL circuits.
RTL had a much wider supply range, IIRC.
FWIW,
Chuck
Just wanted to pose the question to the group in regards to the gummy
pinch roller problem in the HP-85.
Anyone know where I can find a commpatible, hard plasic pinch roller?
Not me, but saw this mentioned elsewhere (from New York):
http://buffalo.craigslist.org/sys/540478438.html
> Date: 2008-01-15, 9:04PM EST
>
>
>
> I'm clearing out some of my collection of older Unix-based systems,
> and at this point, I just want to be rid of them. I'm offering them
> for $20 each. Any less than that, and I'll part them out, and
> reclaim the gold. If you want more than $100 in gear, let me know,
> and I'll work out a deal with you.
>
> Most of these systems all worked the last time I used them, and all
> have CPU's, memory, and a disk. Some of the rest of them I never
> got around to doing anything with, so I don't know for sure if they
> have a disk. I also don't know for sure what the exact specs are --
> the model numbers don't really help, because I usually reconfigured
> them when they arrived. Some of these systems take proprietary
> keyboards and mice, which I may or may not have laying around.
> Others (like Sun, for example) I have more keyboards than I know
> what to do with.
>
> I do have ISOs of operating system installation CD's for most of
> these systems, which I can burn onto DVD-R in trade for a bunch of
> blanks.
>
> Here's a list of the machines that need homes:
>
> - DEC/Digital MicroVAX 2000; this one doesn't have a disk, so it'd
> have to be net booted over a LAVc.
> - Silicon Graphics Indy; I have two of these to move.
> - DEC/Digital DEC 3000 Alpha workstation
> - DEC/Digital Personal DECstation 5000/25
> - Sun SPARCstation 2; not sure if this one works anymore -- you can
> have it for free
> - Sun SPARCstation 4
> - Sun SPARCstation 5
> - HP B160L
> - HP C240
> - IBM 43p
> - Sun Ultra 10
> - Silicon Graphics Indigo2; a few Express graphics systems and a
> couple Impact graphics systems. The R10k Max Impact with a lot of
> memory is something I'd like to get $50 for.
>
> Non-workstation stuff that I want to move:
> Chaparral Fibre Channel to SCSI bridge
> Brocade Silkworm 2800 -- two carcasses, with one supply in each --
> one has the password set, and the other doesn't boot properly, and
> I don't use Brocade, so I don't need them.
>
> I also have Fibre Channel and SCSI storage and accessories, which
> would be more than the $20 each. I have 73GB SCSI drives in
> UltraWide SCSI arrays, and I have 181GB FC drives in small
> standalone enclosures. I do also have 1G/2G/4G Fibre Channel PCI
> cards, cables, GBICs/SFPs, etc. If you need anything to do with FC/
> SCSI storage, let me know.
>
> Thanks,
> Chris
>
>
>
>
> * Location: North Tonawanda
> * it's NOT ok to contact this poster with services or other
> commercial interests
>
>
>
>From: "Jason T" <silent700 at gmail.com>
>
>
>>> From: Alan Perry <alanp at snowmoose.com> <alanp at snowmoose.com>
>>
>>> A friend of mine has a Coleco Adam (and bits to go with the system) that
>>> he wants to get rid. I do not yet have the complete list of what he
>>> has. Anyone here interested in it? It is located in Shelton, WA. It
>>> sounded like it was free, but I need to confirm that.
>>
>>
>
>Any idea if he's willing to ship it?
>
I expect that he is going to ship it (at the expense of whoever gets it).
My friend was quite surprised when I forwarded him e-mail from 4 people
who were interested in it.
alan
> > Does anybody know why the 7400-series TTL used +5V for Vcc? I've
>
> ---snip---
>
> To make them plug compatable with DTL. Next!
> Dwight
OK, if that's the case, then why 5V for DTL?
-Bobby
>
>Subject: Supply voltage for 2N2/256-BSCP
> From: Robert Nansel <bnansel at bigpond.net.au>
> Date: Wed, 16 Jan 2008 21:24:59 +1030
> To: cctalk at classiccmp.org
>
>On Wed 16 Jan Brent Hilpert said:
>
>> ...
>> I hope you're not looking to mimic TTL - you'll have trouble sourcing
>> multi-emitter transistors in discrete form. (I know - it's outside
>> your design
>> constraint anyways.) More seriously, looking to TTL or standard DTL
>> ICs for
>> design would kind of chew up the transistor count very quickly. Is
>> there a
>> reason you're not looking to period/original discrete-component
>> logic designs?
>
>I am using discrete diode-transistor logic; I'm just trying to
>figure out what a sensible Vcc should be. I've seen discrete
>transistor logic designs with Vcc voltages from 3.6V clear on up to
>90V, plus and minus (and often both). I suspect the higher voltages
>were more out of habit from vacuum tube days, but perhaps there were
>other reasons.
More in the realm of other reasons. Transistors of the day could not
switch much current so I^2R ruled where higher voltage at the current
they could switch was used to get enough power. This was balanced
against device breakdown voltages. Other factors that are to be
considered is higher voltages allow larger signal swings for better
noise immunity at the cost of speed (R*C).
>Since I'll ultimately run this whole thing from batteries, I would
>naturally prefer to deal with 6V or 12V (or even 3V or 4V, depending
>on the battery chemistry), less the <mumble> dropout voltage of my
>regulator.
Forget batteries. The voltage stability will be important and as you
get enough powered elements you'll find that all those milliamps start
to pile up to amps, potentially lots of them.
I'd stick to 5V for interface to current parts where needed but you
might find time to look at old machines and their design. One of the
things done was -V to reverse bias transistors to help with stored
charge for faster switching. The -V was in the range of -3 to -10V.
The most recent of transistor machines like the PDP-8 (link-8 too
as well as early DEC modules and the TX2 machine) would be an example
to look at. FYI: the really ond machines used PNP transistors as the
Germainium technology was better able to make those, that only means
all the votages are "upside down" compared to what we currently expect.
>So far I've been able to keep everything in the ALU data path to a
>depth of two diode gates. I'm using the complementary outputs from
>three flip-flops for true and inverted versions of the A-word and B-
>word bit streams and Carry inputs to the adder. It takes more gates
>this way, 25 diodes but no inverters, versus 12 diodes with two
>inverters.
Watch fanout, that is output of the FF being loaded with enough current
sinks to inhibit operation or make for lousy noise immuunity. Many
designs used enough inverters to avoid needing buffers, again a
balanacing act.
Allison
On Wed 16 Jan Brent Hilpert said:
> ...
> I hope you're not looking to mimic TTL - you'll have trouble sourcing
> multi-emitter transistors in discrete form. (I know - it's outside
> your design
> constraint anyways.) More seriously, looking to TTL or standard DTL
> ICs for
> design would kind of chew up the transistor count very quickly. Is
> there a
> reason you're not looking to period/original discrete-component
> logic designs?
I am using discrete diode-transistor logic; I'm just trying to
figure out what a sensible Vcc should be. I've seen discrete
transistor logic designs with Vcc voltages from 3.6V clear on up to
90V, plus and minus (and often both). I suspect the higher voltages
were more out of habit from vacuum tube days, but perhaps there were
other reasons.
Since I'll ultimately run this whole thing from batteries, I would
naturally prefer to deal with 6V or 12V (or even 3V or 4V, depending
on the battery chemistry), less the <mumble> dropout voltage of my
regulator.
So far I've been able to keep everything in the ALU data path to a
depth of two diode gates. I'm using the complementary outputs from
three flip-flops for true and inverted versions of the A-word and B-
word bit streams and Carry inputs to the adder. It takes more gates
this way, 25 diodes but no inverters, versus 12 diodes with two
inverters.
