Funny idea!
I didn't do much F8-assembly besides the copy table routine, but learned some when on-the-fly disassembling Boris / Delta-1.
I worked more on the soldering side. Tried all possible Chip Select combinations for the EPROM, but the strange RAM behavior still happens.
These are the two most logical connections, they work for a while, but then pieces get lost or appear in RAM (Version 2), the display begins to flicker and gets garbled (Version 1). I also tried tying one of the CE's to GND.
I believe my EPROM's aren't either fast enough or that /OE (Vpp) pin isn't TTL compatible.
Code:
Original Mask-ROM Version
(A-11 of 2332 Mask-ROM is pin 18!)
F8-3853
A13 ------------> /CE1 of 2332 Mask ROM (pin 20)
(pin 30) |
| |\
---| |o----> /CE1 of 2111 RAM (pin 15)
|/
CPU
READ ------------> CE2 of 2332 Mask ROM (pin 21)
(pin 34) |
| |\
---| |o----> Out Disable of 2111 RAM (pin 9)
|/
Eprom-Version 1
(A-11 of 2732 Eprom is pin 21!)
F8-3853
A13 ------------> /E of 2732 Eprom (pin 18)
(pin 30) |
| |\
|--| |o----> /CE1 of 2111 RAM (pin 15)
|/
|-> /OE (Vpp) of 2732 Eprom (pin 20)
|
CPU |\ |
READ ---| |o----> Out Disable of 2111 RAM (pin 9)
(pin 34) |/
Eprom-Version 2
F8-3853
A13 ------------> /OE (Vpp) of 2732 Eprom (pin 20)
(pin 30) |
| |\
|--| |o----> /CE1 of 2111 RAM (pin 15)
|/
|-> /E of 2732 Eprom (pin 18)
|
CPU |\ |
READ ----| |o----> Out Disable of 2111 RAM (pin 9)
(pin 34) |/