Kurt, no problem at all. You've done some nice work to accomplish this. Very cool. Steve
On Tue, Jul 16, 2019 at 11:26 PM Kurt McCullum <ku...@fastmail.com> wrote: > I wanted to give my thanks to Stephen Adolph for tracing down the bank > selection pin on the NEC main board. After some testing and a small bit of > soldering I can confirm it works. For mine I have SARDOS on Bank 1 and > UR-2 on Banks 2&3. > > For those interested in this modification the instructions are below. > > 1) Solder a wire to the underside of pin 15 on U53. You will need a couple > inches of wire. I used AWG 26 wire. > 2) Replace the 27C256 32k EPROM with a 27C512 64k EPROM. The lower 32k > will be the EPROM for bank 1 and the upper 32k will be the EPROM for banks > 2 & 3. (I have the binary image if anybody wants to make one) > 3) Bend pin 1 of the 27C512 EPROM out so that it wont go into the socket. > 4) Solder the wire from U53 to pin 1 of the 27C512 EPROM. > 5) Insert the EPROM into the socket making sure pin 1 is clear > > Cold start the machine and you now have 2 ROMs to work with, each with > it's own bank of memory. Enjoy. > > Thanks again Steve! > > Kurt >
