HP-71B CMT Card Reader Memory Module Internal

[Sylvain Cote]

About HHP 71 M/M modules ...

HHP has created 32KB RAM & EPROM PCB's that they reuse into all their modules.

The 32KB RAM PCB contains ...
-> 1 x HHP designed printed circuit board
-> 1 x HP 1LJ4-0301 custom memory controller chip
-> 4 x Hitachi HM6264LFP-15 8KBytes @ 150 ns

The 32KB EPROM PCB contains ...
-> 1 x HHP designed printed circuit board
-> 1 x HP unmarked custom memory controller chip (probably 1LJ4-0301 as well)
-> 1 x EPROM socket compatible with 27256 (32KB), 27128 (16KB) & 2764 (8KB) EPROM @ 200 ns

HHP 71 M/M 32KB RAM has one RAM board
HHP 71 M/M 64KB RAM has two RAM boards soldered together
HHP 71 M/M 96KB RAM has three RAM boards soldered together
HHP 71 M/M 32KB RAM / 32KB EPROM has one RAM board and one EPROM board soldered together
HHP 71 M/M 32KB EPROM has one EPROM board

Sylvain