10 Oct
2019
10 Oct
'19
10:22 a.m.
On 2019-Oct-10, at 5:33 AM, Wouter de Waal via cctech wrote:
Funny, the usual goto reference for early 6800-series chips is the 6800 Micro System
Design manual:
http://bitsavers.org/components/motorola/6800/MC6800_Microcomputer_System_D…
but it's not in there.
There are a couple of other 1K ROMs however (6830,68308).
Might compare pinout with those.
Very likely a
semi custom or custom memory device, due to the prefix.
Armed with that and the fact that pin 1 connects to the leadframe I figured maybe
it's something like the 6830 Mikbug prom -- 0V on 1, 5V on 12, data on the left,
address on the right. Tried reading it like that (for all 16 combinations of chip selects)
but 0xFF throughout.
So I popped the lid, stuck it under a microscope. The chip says "MCM6816" which
is in fact a 1k ROM.
Anyone have more information on the 6816 ROM?