On 3/23/20 10:00 PM, Tom Wilson wrote:
On Mon, Mar 23, 2020 at 6:30 PM Brian K. White <[email protected]
<mailto:[email protected]>> wrote:
There is also a fairly good cheat sheet built right in to REXMGR.
There are still a mystery or two though. For instance, what is the OS
tab? "OS" sounds like it must be the main rom feature, and the screen
even looks like it, but the main rom images are managed in the SYS tab.
That's exactly what it is. You have to connect two wires from the REX to
the system ROM and the ROM socket. (You have to lift the CS pin on the
ROM chip to make it work.)
Once you've done that, you can store 32K ROMs on the REX and use those
to replace the system ROM. This would let you run custom firmware on
your system... however, as Stephen has already pointed out, it may be
preferable to save the CPLD and program space used by this feature and
use that for something else.
I know how the min rom feature works. I even made a special pcb just to
facilitate using it.
It allows you to route the /cs line out to the option rom bay, and back,
such that you can remove the REX and re-activate the internal rom
without opening the case again to re-install the original chip. Also
provides a no-solder hookup with pins and dupont jumper wires.
http://tandy.wiki/FlexROM_100
http://tandy.wiki/FlexROM_102
Except, for 102, the original rom is soldered, so you have to desolder
that to install a socket on T102, but you'd have to that or worse anyway
on a T102, so at least this is the minimum hassle, least hacky end
result possible.
--
bkw
