#Retro
Retro computing, such as a memory upgrade for the IBM 5155 Portable.
- Upgrading an IBM PC/XT Motherboard with 1MB of RAM
How I filled all four RAM banks of an IBM 5155 Portable's 64-256KB XT system board with 41256 chips and replaced the U44 decoder PROM with a GAL16V8 to get 640KB plus up …