PLAster c128, PLA Replacement For MOS 8721, Commodore 128 Available Now and made by: ToTs RETRO PLAster c128, Is a Modern PLA Replacement For c128, c128D and c128DCR What is PLAster c128? PLAster c128 is a modern energy efficient, plug-and-play replacement for the MOS 8721 PLA (Programmable Logic Array) chip used in the Commodore C128. How do I use the new PLAster c128Simply remove the original MOS 8721 PLA in position U11 and insert your NEW PLAster c128 in its place. When upgrading your chips I recommend putting Heat sinks on all your original commodore chips to help with heat dissipation, also if replacing a chip, I always like to put a socket into the board, this will raise your chip and reduce internal clearance because of this I generally do not put the original shield back and don't recommend this, What is PLAster c128? PLAster c128 is a GitHub Open Source Project created by BackBit, that is openly available to everyone. What makes the PLAster c128 Awesome? Modern chip design allows for Low Energy Consumption and low heat Uses Exact Equations used in original MOS 8721 Compatibility Mode: Switch allows cartridges to work in FAST mode KERNAL Mode: Switch allows BackBit cartridge (and maybe others) to replace KERNAL ROM PRIVATE EYES Mode: Switch sets bus high to facilitate in-circuit testing. When Do I Replace My PLA? The Original Commodore 128 PLA, the chip located in U11 usually fails from age and internal corrosion. If your commodore 128 model is experiencing the common issues of a failed or failing PLA listed below, it may be time to upgrade your PLA. Issues can present as.... Total Black Screen Garbage Screen Solid Screen Colors Flashing/Rainbow Screen Overheating/Temperature Spikes Unstable Operation/Unexpected Freezes Peripherals Unresponsive Incorrect Memory Count/Out of Memory (if you need ram, I carry that as well in the link below) Commodore Ram Replacing your PLA is a great start however, may not always fix your problems as RAM (U34-U45), MMU MOS 8722 (U7), VDC MOS 8563/8568 (U22), VIC-II (U21), CPU MOS 8502 (U6) and Kernal/Basic ROMs (u33,u34,u35) can produce overlapping faults and failures. Also MOS 8701(u8) and MOS 74ls257/258 (u14/u15) can cause similar issues. If you have a functioning original MOS chips, placing Heat Sinks on them to protect then from excessive heat can potential help them to last longer. Any Questions Please Do Not Hesitate to ask.
