This is a tested and working project

This is a 512K 8bit ISA RAM card designed for XT class PCs to increase your RAM up to a maximum of 640K conventional. The RAM is configurable in banks of 64K for maximum compatibility with various memory configurations. Each bank can either be set to a low address, high address or disabled entirely. Although not strictly necessary, when ordering you may prefer to have the edge connector chamfered/bevelled.

Please see the original githiub page for the DIP switch settings.

GitHub

https://github.com/oddsocks1024/XTra-RAM

BOM (THT)

16 x 10KΩ Axial Resistors - ¼ watt

1 x 74LS245 20pin DIP

2 x 74LS157 16pin DIP

1 x 74LS151 16pin DIP

1 x AS6C4008-55PCN SRAM 32pin DIP

5 x 100nF Ceramic Capacitors

2 x 47uF Electrolytic Capacitors

1 x 10uF Electrolytic Capacitor

IC sockets optional