ITT 3451 Data Entry Terminal

Built like a brick, mostly with aliminium castings. This bloody thing weighs 45 kilos! I'm going to say there are not that many of these around any more, purely because of the scrap value of aliminium.

TITLE ITT 3451/1
CODE DEZ4103A002
SERIAL No. 0425

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.

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, and the empty 28-pin socket takes a UART for the serial connection, but that was never fitted.


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.

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