32kb RAM Expansion PCB for Commodore VIC-20

Operating principle: Adds 32KB of static RAM, divided into four blocks of 8KB at addresses $2000, $4000, $6000, and $A000.

The result is an additional 24KB of memory for BASIC programs (totaling 27.5KB) plus 8KB in the cartridge space.

Features:

• Write-protect switch, allowing safe execution of cartridge images with copy protection.
• Main on/off switch enabling operation as a non-modified VIC-20.
• Reset button.

Main components: SRAM chip HY62256A 32KB (DIP28, min. 100ns), logic circuit 74LS147 (DIP16), two SPDT slide switches (3-pin), two ceramic capacitors 100nF, electrolytic capacitor 220µF, tact switch button, IC sockets.

Project:
https://www.pcbway.com/project/shareproject/COMMODORE_VIC_20_32KB_MEMORY_EXPANSION_CARTRIDGE_ver_951026_a9421870.html