Hi Guys and Gals,
FYI
After 20 some years of searching for the solution to convert my Emulator II with a Rev 1 digital board into a Emulator II + I have finally found the solution.
I've outlined the process below for anyone that wants to do the same.
Open up EII
Remove piggyback memory board
You will need to remove jumper wires from W2 & W3
You will need to add two new jumper wires from W3 to W4 and from W1 to W2.
These will be in a vertical line to each other.
Previous jumpers are running horizontal.
Replace the 32 64k memory drams on the digital board with 32 256k memory drams.
I replaced IC11 & IC98 with new CD74HCT138E
I bent the bottom right leg underneath when replacing IC98 to match the one that I pulled.
Replaced the Main Boot Rom with one that I burned using the E2newrMain_HDMB2_3_MAIN.bin file poste by czh90 from the Yahoo group site.
I've booted up using an OS3.0 disk that I had and it works fine for now but will upgrade to OS3.1 as soon as I find a disk or upgrade to the HXC.
Links to the parts I used
I'd recommend ABRA Electronics as they had the DRAM the 74HCT138 plus all the stuff I needed to build a new floppy cable to get ready for the HXC update that I'm doing next.
DRAM 150ns super cheap 65 cents each
https://abra-electronics.com/ics-semiconductors/dynamic-video-rams/41256-150-16-pin-256k-x-1-150ns-dram-41256-150.html74HCT138 35 cents each
https://abra-electronics.com/ics-semiconductors/74hct-series-dip-package/74hct138-74hct138.htmlBlank Eproms
https://abra-electronics.com/ics-semiconductors/eproms/m27c64a-15f1-eprom-u-volt-64k-bit-8k-x-8-150ns-fdip-28-m27c64a-15f1.htmlI used a TL886II Plus USB eprom programmer to burn my chips got it off of Amazon.
Well there it is in a nutshell.
Post if you have any problems or need an eprom burned to do the upgrade.
Thanks,
Dana
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