Panasonic HHC ROM 'capules'

[Jeff_Birt]

(01-06-2023 06:55 AM)brouhaha Wrote:  The SnapFORTH development ROM was 16KiB and wouldn't fit in a capsule. It was an expansion box, about the same size as e.g. the RS-232 expansion box, but without an I/O connector. Inside there are EPROMs and logic for bank-switching.

Looking at the HHC documentation about SnapFORTH they mention the SnapFORTH capsule multiple times. The only sort of memory expansion I can find that plugged into the system bus is a 16K RAM expansion. I also see that an EPROM burner is mentioned. Looking at the ROM images I got from the Silicium forum it seems that both SnapBASIC and SnapFORTH were 16K capsules. Perhaps they used the EPROM box until they could get the custom 16K, 24-pin ROMs made?

EDIT: Reading some other Panasonic HHC related messages from the linked archive there was a reference to a 3rd party EPROM box (bottom mounted) and a reference to a side mounted SnapFORTH compiler add on.

Thanks for the tip on the SnapBASIC image being corrupted this line in that message:

"The HHC inverts address line A12 to the ROMs, so the two halves of the EPROM are logically swapped." explains the file naming convention in the ROM files I received, i.e. the use of 'swapped' in some file names.