(Crappy ascii art trigger warning) | |
# Day zero | |
Behold, I got a box! | |
.-------------------' | |
.------------------./ | | |
| ______________ | | | |
| |From ebay with| | | | |
| |love | | | | |
| `````````````` | | | |
| | | | |
| | | | |
| |/ | |
.`------------------' | |
Or, here is an actual... | |
photograph | |
... rather than a textual representation. | |
You see, a few days earlier, I had ordered a HoneyWell terminal | |
from ebay. I am not particularly in the habbit of buying a ton of | |
stuff from ebay, but this is a HoneyWell terminal!! The reason for | |
all of my excitement is that I am rather fond of the Honeywell | |
(and earlier General Electric) family of mainframes this thing was | |
used with, namely the DPS series, and the GCOS (or earlier, in the | |
GE days, GECOS) operating system that ran on them. (they also ran | |
multics) - and until recently anyway (because the guy is selling a | |
bunch of them) you NEVER saw these- or any type of DPS-related | |
stuff on the bays of Eeeeh... I do | |
remember once upon a time a tape system being sold, for looooooots | |
of dollars, but that's about it. | |
So cool. I excitingly grab a sharp object and cut the box open, | |
and reveal: | |
________ | |
/_////__/| | |
|| | | | | |
||____|_|/ | |
/###### #/ | |
--------` | |
... It's contents! | |
Alright awesome! Just look at it! It's relatively clean, but still | |
has a nice patina. It even has an old printout with random names | |
labeled "buyer names" still stuck to the side. What tales could it | |
tell? But more importantly, will it work?! The ebay auction said | |
it did, but I'm not sure if I trust just powering on this thing | |
and frying it without having a look at the innards first, and at | |
least poking around with a multi-meter for obvious shorts.... | |
*pokes around the terminal to see how it might open*... but ooh... | |
what's this?! It's modular! It appears the main circuit board just | |
slides out as one solid module, encased in plastic: | |
.---------. | |
|\ /| | |
| | | | | |
|=========| | |
|________\| | |
________. | |
|\ \ | |
\ \--------- | |
\|_===__==_| | |
Alright, you get the idea,.. here's the picture. | |
With the board out, I could peek inside and figure out that the | |
cover was held in place by 2 screws, once those were out, it | |
opened up like the hood of a sportscar :) | |
This would be hard to draw, so here's just the picture ;) | |
So we see an board with the crt driving circuitry, and the metal | |
case on the left houses the power supply. At this point I was a | |
little worried because you can see some blackened metal in one | |
spot on the PSU. I tried to peek within and the components there | |
didn't look obviously damaged- but of course I can only tell so | |
much without opening the power supply cover. Instead I opted for a | |
quick measure of the outputs, which seemed fine. | |
I closed the cover backup, and re-inserted the main board module, | |
and decided to just go for it, and sure enough, it powered up into | |
it's built-in test mode. | |
First power-on picture. | |
# Day one | |
Alright, so now I had to figure out how to actually talk to this | |
thing. It has a db25 connector on the back labeled "J1/Data Set", | |
which I assume is where the electrons are supposed to enter. | |
Hoping that it's just a plain db25 serial connector like any other | |
terminal, I hook up a db25->db9 null-modem cable I have laying | |
around. I was using this cable with my panasonic luggable in the | |
past, so I know it should at least work in theory, if it were | |
plain serial. After hooking it up and messing about a bit with | |
various stty settings I do get garbage on the screen when I press | |
keys on the terminal. To my surprise i had to use 7 bits per | |
character instead of the usual 8 (cs7) - but unfortunately, I can | |
only get data in one direction; pressing keys on the terminal | |
makes characters show up in my screen session, but not the other | |
way around. I was expecting at least some garbage characters even | |
if the settings were not correct, but nothing. Well, | |
darn. | |
Back connectors (1) | |
Back connectors (2) | |
# Day two | |
So, the fact that I got readable characters in one direction is | |
actually very good news. This meant that it's talking plain 'ol | |
serial as I had hoped. The next step was to make a cable and see | |
if I could figure out what other pin the terminal might receive | |
data on. I got a few of those screw-terminal db25 and db9 | |
connectors, and cut up a piece of scrap serial cable I had laying | |
around, and wired up a plain full null-modem cable as a starting | |
point. Unsurprisingly, the homemade null-modem cable gave exactly | |
the same result as the commercial one. So then I went and took a | |
closer look at what all the 'extra' pins on a db25 serial | |
connector are for. It turns out there's actually a second set of | |
data pins, there is a second Read/Transmit-Data pins, etc,... As a | |
complete stab in the dark I tried bridging the normal RD pin with | |
the RD(2) pin, and to my surprise I now had everything working in | |
both directions! I don't know WHY the read-data needs to go to the | |
second one instead of the same set the TXD goes to, but it is what | |
it is! (If anyone knows, let me know!) - I couldn't find any | |
technical documentation for this terminal, just a few (very cool) | |
sales brochures. After messing with my Linux machine's inittab and | |
trying varous TERM variables, I managed to ssh to sdf and open up | |
commode: | |
Wiring of the connector | |
Commode | |
Commode (close-up) | |
Wiring diagram | |
# Day three | |
Alright, so now I've got a somewhat usable terminal. What's left, | |
you ask? Well! It's not quite perfect, you see. When I open up | |
vim, everything just sort of scrolls off-screen and the terminal | |
makes a bunch of unhappy bleeps. No, we can not just leave it at | |
that. We have to figure out what the appropriate TERM variable is | |
for this thing and see what else it can do. Some of the marketing | |
material mentioned it being able to do line graphics, and | |
potentially other fancy stuff by sending it SI/SO control | |
characters and what not. Given the lack of any real documentation, | |
I decided to write a little program that allows me to send it data | |
in a controlled way. | |
Some output of the test program | |
As you can see in the above photo, I did end up figuring out how | |
to toggle the line-graphics mode, well - i'm getting ahead of | |
myself - the FIRSt thing I noticed was that I could send it VT52 | |
control characters, like for instance \033A to move the cursor up, | |
but -not- ANSI control characters like \033[A - For this reason I | |
settled on the VT52 TERM variable/termcap file. Although it's not | |
quite perfect. Vim is still broken; and when looking at the | |
documentation of the VT52, it's supposed to enter line-graphics | |
mode with \033F and exit it with \033G ; but for this terminal it | |
is exactly backwards! It enters line-graphics mode with \033G and | |
exits it with \033F - I thought the wikipedia page of the VT52 was | |
backards first, until I went and looked up the actual old manual | |
and confirmed it there (unless the original manual was backwards | |
and wikipedia copied the mistake, which is of course also possible | |
but unlikely) - so for now I will assume that this honeywell | |
terminal is backwards from the VT52 - which is actually kind of | |
funny. So with that in mind, it seems obvious that I will have | |
to do more testing, and craft up my own termcap file for this | |
thing. Which, I haven't finished yet at the time of writing, but | |
when and if I do, I'll put it up here along with the other | |
documentation and findings of my experimentation. | |
The other thing is, if you notice in the pictures, there's some | |
diagonal lines going across - that's the horizontal return being | |
slightly 'off' - it probably needs some caps replaced, so that's | |
another thing on the todo list. | |
I hope you enjoyed my little story! :) | |
# Update | |
I've managed to "fix" the CRT so it no longer looks like a wash | |
of green with diagonal lines. It just needed a bit of tuning on | |
the inside. The pcb for the CRT has a bunch of potentiometers | |
and variable coils for tuning, as they typically do. There was | |
a tunable coil for the horizonal width and the brightness, after | |
adjusting that, it looks so much better! Here's the result: | |
Fixed crt | |
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