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. You can also configure RAM in the UMA area but that is very system specific. 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. If chamfered/bevelled you may wish to have no solder mask in the connector area.

Please see the original github 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