Teeprom is for the option rom.
FlexROM_100 or FlexROM_102 is the main rom.
Well really just the 100.
No one really needs the 102 version because for 102 you can just use a
plain 27C256 which is a lot simpler. Just for 102 you want to get some
chipquick or fastchip desoldering alloy to get the old rom out without
drama or damage.
For main rom in a 100, FlexROM_100,
http://tandy.wiki/FlexROM_100
or Mike Stein's board.
https://oshpark.com/shared_projects/Kil9S1ya
--
bkw
On Sat, Oct 31, 2020, 7:12 PM Stephen Adolph <[email protected]
<mailto:[email protected]>> wrote:
On Sat, Oct 31, 2020 at 5:52 PM Joe Grubbs <[email protected]
<mailto:[email protected]>> wrote:
Aww yeah! I'm liking where this is going. Will the sluggish
original ROM handle 8Mhz+?
No, for sure not. Right now I have a 120nsec EEPROM in the socket
and it supports 6.2 MHz.
If I simply place the original ROM back in - no go.
But the Main ROM is the easiest thing to replace. It is already
socketed! There are many ways to address it.
So far here are the changes to run 6.2 MHz (my current setup)
1) you need a faster CPU + crystal. I'm making a board for that.
Which CPU - TBD. There are a few choices. (I really should try the
stock CPU and see how fast it really is. I am currently using the
8MHz Tundra 80C85 CPU)
2) you need faster RAM. You could use REXCPM to solve that
problem. Otherwise... a lot of soldering work!
3) faster main ROM. Teeprom would be a good solution here.
4) improved M2. stock = TC40H245 (good to 5MHz). I have
piggybacked 74HC245 (6MHz)
I'm puzzled by what is failing to work at 8.2 MHz. Everything so far
looks ok. I'll keep poking around....
