Burroughs TD831




What a nice design.

(and the back if you're morbidly curious)

This thing has a lot of 6821s. Three 6850 UARTs I can understand.

(and the back if you're morbidly curious)

Two banks of 4027 4kx1 dynamic RAM. Installed at different times because the older (?) RAM chips read

1627 6941
and the later (?) ones
There are eight ROMs installed, with space for 32 ROM chips. As far as I can tell, these are 16 kilobit (2k x 8) mask PROMs with programmable chip-select lines.

Edit 2023-06. Turns out someone scraped this website and uploaded my pictures and initial ROM dumps to bitsavers. And the initial ROM dumps (B1.TXT to B8.TXT) are rubbish. I think I was reading too fast for the chips, I added a 1ms delay to my code and the result looks slightly more sane.

There's a thread about all of this on VCFED.

The CPU board also has a single 82S123 32x8 fuse ROM presumably used for address decoding.

(and the back if you're morbidly curious)

Video controller (I assume) is marked

AMI 7852AG
1627 6834
The "7852" is probably the date code.

The character generator ROM is marked

1627 4458
AA78 43
I have no idea how to read it yet.

2 x AM9112 / C2112-1 RAMs

Four 32x8 82S123 fuse ROMs

[Image] Hit Count
hits since 2018-05-04.

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