Commodore 64 PLA (906114-0) replacement PLA20V8:
If you are a bit familiar with the hardware of the Commodore 64 you know that the PLA chip in the Commodore 64 is perhaps the most failing chip of the entire Commodore 64 today.
You will find references to these chips under the following references 906114-01, 251064-01 and the 82S100.
This PLA (Programmable Logic Array) is the custom chip that manages the memory map and memory bank switching.
Unfortunately, these chips are no longer available for a long time, if you find one that is usually used and the (Long-term) operation is not guaranteed.
The PLA20V8 is the brainchild of Daniël Mantione, who devised an alternative to the functionality of the Commodore PLA chip based on 2 GAL chips.
And that approach, according to all kinds of tests, resulted in the 'most compatible' PLA replacement, without any known drawbacks.
In fact, it's so compatible that there's no need to do anything for any revision of the C64.
Does the PLA20V8 work in all C64 motherboards?
Yes, except for the shortboard, The shortboard (assy 250469) uses a completely different type of chip.
The following boards have been successfully tested, Assy : 326298, 250407, 250425, 250466, 251103 (SX64), and C64 Reloaded MK1.
Assy : 250441 and KU-14194HB have not yet been tested, but in all likelihood no compatibility issues are to be expected there either. For all tested boards, both the PAL and NTSC versions have been tested.