Re: REU Rom Socket?

From: Randy Winchester (randy_at_MIT.EDU)
Date: 2000-01-11 15:55:12

At 11:23 AM 1/11/2000 +0800, you wrote:
>Hello All,
>I was recently poking around inside my 1750 REU wondering whether I'd risk
>my one-and-only REU to a 2MB expansion.... and I noticed that there is an
>area for a ROM socket and jumper pads labelled ROM Hi, ROM Lo etc....
>What are these for?  was RAMDOS been implemented in ROM on some units?  any
>binary images exist and info about the jumper configuration and memory map?
>- Nick

RAMDOS was implemented in ROM on all of my 1750 REUs and about 2500 others
that I know of.  I included RAMDOS (along with the patch to address 2MB) in
KeyDOS ROM.  As far as the memory map, it's set up as a function ROM with
the same addresses as a C128 internal function ROM (documented in the C128
Programmer's Reference Guide), only in Bank 8 instead of Bank 4.  One of
the big tricks with KeyDOS was to have the ROM check and remember its bank
location, so the same ROM could be used either as an internal function ROM
or externally in an REU.

You can find all the information about KeyDOS at but be aware that I
haven't sold any for about two years and currently don't have a C128 system
set up, so it would take me a week or so to make one.

Randy Winchester,
MIT Cable Television,,
Room 9-050, x3-7431
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