18 Sep
2002
18 Sep
'02
2:18 a.m.
At 07:05 AM 9/18/2002 -0700, you wrote:
ADM-3A/HP 6144 Terminal Updates
ADM-3A
I just "restored" a nice brown/beige ADM-3A. I got a
new CRT for USD 50, and then noticed that this unit
didn't have lower case installed. What the "lower
case" option consisted of was a lower case 2513-type
ROM and a couple of 2102-1 chips, all of which can be
inserted into sockets on the motherboard. Problem is,
the lower case 2513 LC ROM is not readily available.
So I built an adapter to make the multi-voltage 2513
PMOS chip I had from my other ADM-3A look like a 2716
to my EPROM programmer/reader. I read the upper and
lower case chips, programmed a lower case 2716, and
made a small adapter from to make the 2716 "look" like
a 2513 in the socket, installed the chips/adapter,
flipped a few switches, and voila!
This is detailed at
http://juliepalooza.8m.com/sl/adm3a-2.htm
I don't think that this is the FIRST time that this
has been done - but it might be among the last!
Nice! Back in the day, at Purdue University, we modified
a number of ADM-3a terminals with a 2x PROM which
contained an APL character set. We then added a toggle
switch in the little metal plate on the left of the keyboard
and stuck stickers onto the keyboard so that you could
select normal terminal mode or APL mode and program
in APL...
--tom
HP2644A
I've finished the keyboard, and got some paint that
fairly matches what I THINK that the original color of
this unit was. A several-hour long job was the buffing
of all (all) of the keys - this made a MAJOR
difference in the appearance of the unit (the keys are
NOT supposed to be chalky yellow).
I found a source for the unusual tube - but they want
USD 225 for it! They assure me that they use a type of
acrylic between the faceplate and the safety glass
that will never yellow, separate, or grow mold. Still,
this is a lot of money, and I intend to do the
hair-raising act of heating a nichrome wire (arriving
soon) to separate the faceplate from the CRT's safety
glass/front. Assuming that I survive with minimal
injury and am capable of writing anything, I will
detail this operation on my web pages.
If anyone has $225 to spend on a tube, contact me. I
beleive that this tube was also used on HP equipment
more worthy of spending $225 on.
http://juliepalooza.8m.com/sl/hp2644a.htm
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