Hi Steve,
At 10:34 PM 9/12/02 -0700, you wrote:
>I picked up on a $10.00 eBay Buy it now an HP2644A
>terminal. This terminal uses little tapes (DC-100A's
>or HP 98200A's).
That's a pretty nifty find! The HP 2644 was HP's first product to use the DC-100 tapes. The 2644 was well covered in one of the HP Journals. According to an article in it, the DC-100 tapes were developed jointly between HP and 3M. If so then the HP tapes must be some of the very first ones made. Perhaps that explains why they're so failure prone. Not only does the media fall of but usually the rubber drive belt in the tape has crystalized and falls apart at the first attempt to use the tape. The DECTape II and DC-100 marked tapes have a high failure rate too but well below the near 100% failure rate for the HP marekd tapes.
It's slightly beat up (mostly in
>shipping in spite of the seller's best and
>professional efforts), but nothing (except see below)
>that I can't repair - I'm pretty sure I can get this
>back to nearly original factory condition. It should
>be a nice complement to some classic micro's I'm
>working with. The HP 2644A is working. It even came
>with the hard to replace RS-232 cable,with an edge
>connector to the unit, weird. Annoying, considering
>that this thing cost several $1000's in the mid
>1970's. It looks like you could put 20 amps of RS-232
>signal through it, given the diameter of the cable!
>
>The 2644A's claim to fame is that it used the 8008
>CPU, and has a tiny mini-operating system, pretty good
>for a machine with 16K of address space. There is a
>web site in Germany with a pong game that is actually
>that you run on the 8008 in the terminal via a
>diagnostic "back door", which I'm looking forward to
>trying. I wonder who wrote it.
Any idea what the HP part number is on the 8008? I have some old junk HP terminals of that style and I'll save the 8008s if I can locate them.
>
>This unit I have doesn't have many goodies like
>graphics or lower case, but for $10, what do you want.
>It's built like a "mainframe", and later models used
>the same everything with different boards plugged into
>the backplane.
>
>I got a few manuals with it; the 2645A and 2648A
>manuals. The 2645 seems to be very similar.
>
>A few questions:
>
>1. The "infamous" HP 98200A tapes are REALLY awful. I
>got a box on eBay, never used, in wrappers, and they
>failed immediately. After taking them apart, I think I
>know why. Even sealed after all these years, the oxide
>was actualy coming off the tape and the reels didn't
>even have clips to hold the tape on. Whatever held the
>ends of the tape on originally, doesn't. Hard to
>beleive that this was an HP product of that era. I've
>got almost 35 year old audio casettes that still work
>and sound great.
>
> I think DC100A's and even DC2000's will work
>according to what I've googled. Any comments?
There have been a bunch of comments about this just in the past week so I won't repeat them but yes the DC-100 tapes and DECTape IIs will work in the HP if you reformat them. The DC-2000 tapes won't work, the tape is wider and the plastic housing is thicker. The drive roller in the tape cartridge also falls half way off of the drive roller in the drive and tears up the roller.
Of
>course, I've already tackled and (probably) fixed the
>"gummy" roller problem. Before I used the drives,
>even. Naturally, I've given away all of my DC2000
>tapes...
>
>2. Has anyone ever seen a CRT develop mold between the
>(bonded to the tube) safety glass and the tube itself?
I've seen that in a lot of HPs including the 9845s and 9835s. I don't know if it's mold or what but it shows up as lots of white spots inside the glass. It seems to show up regardless of how the monitor was stored. A couple of years ago I junked seven HP 64000 LDSs. They all had good CRTS. About a week later I found that the CRTs were the same as that used in the 9835. :-( You might be able to locate a HP 64000 and use the CRT from that.
>The unit itself was probably stored indoors in a
>controlled environment because it was otherwise very
>clean. I'm pretty sure I can get a replacement, but it
>will cost. Too bad, because the tube is really good
>and not burned in whatsoever, which is very surprising
>(the tape heads have zero detectable wear also). Trust
>me, even if it's technically possible, I won't be
>trying to separate the safety glass from the tube
>itself. I hate replacing CRT's. Unfortunately, I've
>gotten good at it.
>
>3. The tab key is missing. Not broken off, just
>missing. I have a "kinda close" replacement, but if
>anyone has a junk HP product of that era with tall,
>"Cherry" keytops, I'll take anything.
I may have one. I have a couple of old HP terminals of that style laying around. I'll check when it's not raining. Remind me in a day or two if you don't hear from me.
Joe
>
>
>Thanks for reading!
>
>
>
>
>
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Received on Fri Sep 13 2002 - 16:12:34 BST