Exxoss TOS 1.4 upgrade for six chip STM
2016-04-20 20.57.27
Six chip STM (fitted with six chip 1.4 in this case) note that the very top ROM socket is offset to the right slightly. The extra chip under it is a Dallas Real Time clock.
2016-04-20 21.08.43
There are two blue wires that need connecting to the ROM area, and as I will have empty sockets, I'm adding pins. Note: I should have used smaller pins really, as these have opened up the tiny clips in the ROM socket, which will need fixing if I ever go back to 'stock'
2016-04-20 21.10.05
2016-04-20 21.15.17
Initial fitment. There are two boards, a 'master' and 'slave' - the Master has more wires coming from it, including two that need to go to two legs on the 68000
2016-04-20 21.15.27
Wires carefully soldered to the processor
2016-04-20 21.28.05
I made an error! In my excitement to fit this, I forgot that the early STM machines have the ROM sockets in a different order, so when I tried to boot with the chips in the earlier pic, I just got a white screen and no disk activity. Swapping thr boards over made it work.
2016-04-20 21.28.11
Working 1.4 :)
2016-04-20 21.35.10
One thing to note is that the original shielding will no longer fit. Two options here - trim the shielding (the hole in the pic is the already present factory 'trim' for stock ROMS) or remove the sockets and solder the new boards directly to the STM.