2 x SN74LS257AN - direct Replacement for Commodore 64 MOS 7707 Chip, (or similar used by commodore at the time)


These Chips are a direct replacement for Logic IC Chips, located at IC postition,, U13 and U25 in the breadbin C64

Typical symptoms when faulty are a blank screen, less than 38911 bytes free at startup or a “garbage” screen.

These chips are sold as a pair as, if you have a fault described as above, you might as well replace both chips, (either chip could be bad, even both could be bad)


* you will need soldering skills / equipment to replace these chips as they will almost always be soldered to the motherboard *


and always socket your chips in  !!!

Here's why its a good idea:

(if you look at your commodore 64 motherboard, and look at the sid chip or the Vic II chip, you probably see that the chips are in a socket, and you can easily remove the chip without desoldering.
The other small chips are almost always soldered into the motherboard. so if you are desoldering any of these chips, its a good idea to add a socket for the new chip as it makes life easier if you want to swap out later on.
but you can always just solder a new chip into the motherboard directly - it's your choice really)