ITT 3451 Data Entry Terminal

Built like a brick -- this bloody thing weighs 45 kilos! Heavy weight steel plate bent and welded, with some kind of thermoset plastic (at first I thought it was aluminium) front panel.

TITLE ITT 3451/1
CODE DEZ4103A002
SERIAL No. 0425
NET WEIGHT 45 kg
GROSS WEIGHT 61 kg
MADE IN JAPAN

Top view. Power supply at top left.

Toshiba MKM0101S 202 Serial 08255.

The foam around the fan has completely perished.

From the top left, give or take.

• Intel 8279 Keyboard / Display Interface. This scans the keyboard, of course. The display part is not used.
• 12K EPROM.
• One 28-pin socket, purpose unknown (I thought maybe "1" should go here).
• Another empty socket (24-pin).
• Toshiba T3444G, which I think might be a 4-bit processor used to control the 8" floppy drives. (See Electronic Design, October 11 1977, also Sharp MZ-80)
• Intel 8257 DMA Controller.
• Intel 8085 CPU.
• Hitachi HD46505 which is a Motorola 6845, same as what is used on the IBM PC MDA.
• Three banks of 16K RAM in 4116 DRAM chips.
• 2 x 2K EPROM, presumably the character generator.
• MMI 6300-1J 256 x 4 fuse ROM, function currently unknown. With 4 outputs it's unlikely to be a memory mapper.

There are five connectors down the left-hand side, the top is the keyboard, the others presumably provide an interface to the mainframe or whatever. Second from the top "JD" would presumably be the serial connector, there's a whole bunch of 1488 and 1489 RS-232 chips there.

At this stage I suspect this unit was used as an offline data entry terminal on to the floppy, running custom software for whatever kind of data the customer wanted to capture, and the empty 28-pin socket takes a UART for the serial connection, but that was never fitted.

Unfortunately Something is Wrong (I suspect when this thing got decommissioned they pulled the EPROM number 1, which is why there's a "NO FW" message) and even if it were working, what does one use it for? (back in the day it would have made a neat CP/M machine maybe, nowadays it could be useful for is a movie prop for something like _Firefly_ or if they get around to making Fallout. But I'm completely out of storage space. So sadly yet another ITT3451 goes to scrap.

The EPROMS:

• IC 45, marked "057" (MB8516)
• IC 46, marked "058" (MB8516)
• IC 74, marked "2" (D2716)
• IC 75, marked "3" (D2716)
• IC 76, marked "4" (D2716)
• IC 77, marked "5" (HN462716)
• IC 104, marked "055" (MB8516)
• IC 130, marked "056" (MB8516)
• IC 118 (MMI 6300-1J)

Reverse Engineering. Just looking at the EPROMs, I'm going to guess IC45 and IC46 contain the factory code, and that the four EPROMS marked 2-5 contain the software. EPROM 5 might even have been added later than 2-4. OK, so let's start with "057"... Yup, looks like it has the 8085 reset / interrupt vectors. A bit more messing around and I'm pretty sure 057 and 058 map to 0x0000 and 0x0800 respectively.

A web search gives me pretty much nothing. Gregor Dietz mentions that he has / had one of these but gives no further info.

• Intel SDK-85 used a 8279 keyboard / display interface.