On 2019-Oct-10, at 5:33 AM, Wouter de Waal via cctech wrote:
>> 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?
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_Design_Data_1976.pdf
but it's not in there.
There are a couple of other 1K ROMs however (6830,68308).
Might compare pinout with those.
