A Relay ALU

A project log for 4 bit TTL ALU

Alternative for the 74LS181 ALU, built in One Square Inch

roelhroelh 11/05/2018 at 09:051 Comment

On the pages of Dieter Mueller you can find a nice Relay ALU with 5 relays. However, this can be improved to the following:

Only 4 relays are used now. The improvement is based on drawing 2 of the carrry generation of the Fast carry circuit described in another log. If you do not want to use diodes, you can instead use a relay contact to disable the carry. Using relays with two contacts, a single relay can disable the carry for two bits.

EDIT oct 2019:  I am very proud that this ALU design was used in the RR6 6-bit Reed Relay computer !

[EDIT. An even simpler relay ALU (3 SPDT relays) was designed and presented HERE ]


Yann Guidon / YGDES wrote 11/06/2018 at 03:02 point

Dieter would be proud ! :-D

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