Re: How can clueless seller tell if IIgs is a ROM 3?

[dempson@actrix.gen.nz (David Empson)]

Mitchell Spector <mitch2gs@hotmail.com> wrote:

>     There is also a leaked beta firmware found in some
> ROM 3 motherboards, these used EPROMs with less
> pins instead of the typical masked ROMs. Fairly 
> uncommon, so hardly worth mentioning.

Hi Mitch

Aren't the EPROMs a greater number of pins? The masked ROMs are 28-pin
chips, but the logic board has provision for a 32-pin chip, and that
would be required for a 128KB EPROM (not enough pins to have VPP as well
as the address pins and CS in 28).

28 pins is 2 (power/ground) + 8 (data) + 1 (chip select) + 17 (address),
with 2^17 = 128K.

-- 
David Empson
dempson@actrix.gen.nz