Picked up something big this morning:
That's an IBM 3270AT - in pretty much mint external condition. The 3270AT is a weird beast, basically a bog-standard early IBM AT with some decidedly non-standard I/O. It's desgined to act as an intelligent terminal for an AS/400 mainframe. That's why it comes with full Model F 122 'Battleship' keyboard. Also an original IBM smoky perspex ProPrinter stand (unfortunately without printer).
Inside:
That's one fully loaded AT - and all of it factory default.
Slots 1+2+3: "PC3270 Display Adapter" video card for the AS/400 terminal stuff. Can emulate CGA and MDA, but better character ROM (sans serif) and do lots of panning/windowing stuff in hardware.
Slot 4: 128kB RAM; the motherboard has 512kB, so this loads it out to 640kB.
Slot 5: Serial+parallel card.
Slot 8: MFM HDD/Floppy controller
Slots 6 and 7 are the fancy ones though, you hook the keyboard up to card 6, part of the stuff is looped through to the DIN keyboard connector but all the extra function things are handled by this card. And then there's card 7, the Host Connect Card, which is somewhere between a NIC and an AS/400-on-a-card. This is how you connect to the mainframe.
Apart from that there's a huge full-height MFM HDD in there (size/brand unknown at present), the original DS/DD 5.25" FDD and a new DS/HD drive on top.
The keyboard is of course the Battleship and the monitor is a 5272. I intend to make an adapter for the Battleship with a Teensy USB gadget. The latter... interesting screen, but looks like non-standard pinout (DE9 connector like MDA/CGA/EGA, but pin 3 missing). Haven't had any luck so far pulling up specs/pinout for it. If I could somehow feed it EGA, it would be a glorious thing 😀
Back:
Probably not readable, but this system was delivered on September 24, 1986, and serviced by the original seller until 1989. From what I gathered from the seller, he was the second owner and didn't have a clue about the AS/400 stuff, he just had it as a conversation piece and something to play old CGA DOS games on. He stopped using it years ago and just left it on the coffee table. His wife wanted to clear stuff up and was aware these things command quite a premium 2nd hand, so they put it up for sale. I had to bid pretty high and send a nice mail to get the chance to pick it up. Unfortunately when they wanted to show it working, things went pear-shaped. Turns out there were shorts galore, and one of the tantalum caps decided to blow while we were looking. Still, external non-leaking battery, so no damage other than bad caps. And it not working knocked a lot off the price 😜