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please help

High telco

Low telco

They both look like tape boards or more likely floptical, to me. Board C is definitely high telco. It’s the other one that is bothering me. It’s definitely not a standard classing hard drive board but there’s nothing else for it above high telco. Hard drive board by omission here. Lucky you. ;)

I actually have a bunch of these in a bin. Generally peripheral. The vast majority are tin-nickel contacts, not silver. Unless they’re pre-90 where they need to be separated and tested on site for potentially upgrade.

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What about the old keyboard board?

Oops. Didn't see that part until after I posted.

Lol
This one is actually silver.

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pic 3 is harddrives from mid 80s industrial copiers. pic 4 same era.

I found the platers from the harddrive

Sorry, wasn’t doubting you. Those older drives used very different technology over all. Many had two boards. Others are dependant on cpu clocks etc for timing.
More to point in out stuff was just very much not standardised.
Split boards usually go as peripheral and high telco or cd board and hard drive board.
Single boards range from low telco to hard drive board.
Depends on the board.
Floptical boards tend to be the same range as there was little consistency in them in the same manufacture.

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