Panasonic HHC ROM 'capules'

[Paul Berger (Canada)]

Any of the EPROM modules I have seen for the HHC have been the Motorola 68764 EPROM that is a 24 pin 8K EPROM different from the more common 28 pin 2764. The compiler "capsules" use a special 16K ROM that uses what would be the -E pin of a 68764 as an extra address pin. This is possible because the ROM capsules are bank selected by controlling power to the capsule instead of using a select signal. I am not aware of any replacement for this very odd ROM module, making duplicating these capsules difficult. Some time ago I purchased one of the kits that GE put together for programming some of their industrial radios and they got around this by having their program ROMs in a plug in module that contains industry standard ROMs. I have not dug into it far enough to figure out how they managed selection of ROMs but there is a signal on the HHC bus to enable external ROM when none of the internal capsules are selected .

Paul.