Editing Amstrad CPC 464 Maintenance Guide (section)

== ROM Health ==

The CPC 464 holds its operating system (Amstrad Firmware v1.0, part 40009) and Locomotive BASIC 1.0 in a single 32 KB mask ROM at IC103 (TMM-23256P-1950). Mask ROM is more robust than EPROM: there is no UV-degradation path. The most common ROM-related fault is a bad socket, not a bad chip. Reseat IC103 if the system boots to a corrupted character pattern or hangs at the prompt.

The English-language firmware part number is '''40009'''; Spanish firmware is '''40037'''; French firmware is '''40050''' (paired with an AZERTY keyboard mat).