From the "85MC01" experience... https://www.amibay.com/showthread.php...rk-in-progress
A pair of replacement 7501/8501 CPUs using a 6502A* N-MOS core - they can handle illegal opcodes!
"CPU4C16":a specific CPU replacement to fit into a C16
"CPU4PLUS4":a specific CPU replacement to fit into a PLUS4
Tested also with "metamerism", "pets rescue",2 versions of "Elite","krill's loader", jiffydos, ......
..
..
........
Features:
A) normal sw N-MOS 6502 behaviour (as 8501, illegal opcode included)
B) The I/O bits are at right places: the self-turbo routines (loaders) will work
C) R/W line is put on 3state and HOLD like as 8501 timings spec
D) TBC technique applied to help the CPU, even in the "worst case", to match the correct bus timings
E) the 2 bytes ram under the CPU port will be not corrupted (on C16 they are reachable by their mirrored address)
F) (*) each 6502 (which you will already find included in the CPU replacement) are selected for 2 specs:
---1) it has to be an N-Mos,
---2) it has to match to the specifics bus timings
Remember that N-MOS 6502 chips are discontinued,
often on market the sold chips are refurbished and relabelled with a label different to the old one:
chips marked as "6502" may not be N-Mos as it have to be, and vice versa (C-MOS, so no execution of the illegal opcode).
I found a chip labelled as "W65C02S" (10MHz C-MOS) that is a 1MHz N-MOS, and some of not working chips marked as "MOS6502A" seem to be MC6809 Cpu...
This mod will be assembled on request, also on sale elsewhere.
The cost:
29€+untracked shipping cost: PPal "FOR FRIENDS" (I can't be responsible for untracked shipping)
29€+tracked shipping cost (+ eventual PPal fees if PPal "COMMERCIAL" )
PM me about the price of small lots of my different items
Other projects for C16 PLUS4 and combined shipping available.
For CPU4PLUS4: please declare whether U4 is soldered onto your motherboard or whether it is on a socket.
-If U4 is on the socket, it takes up more vertical space and CPU4PLUS4 needs to be assembled with high pins and consequently the 6502 chip must be soldered directly onto it.
-If U4 is soldered on the motherboard, it takes up less vertical space, and CPU4PLUS4 can be assembled with short pins and the 6502 chip can be placed on a socket.
For more details contact me via PM,
thanks
A pair of replacement 7501/8501 CPUs using a 6502A* N-MOS core - they can handle illegal opcodes!
"CPU4C16":a specific CPU replacement to fit into a C16
"CPU4PLUS4":a specific CPU replacement to fit into a PLUS4
Tested also with "metamerism", "pets rescue",2 versions of "Elite","krill's loader", jiffydos, ......
..
........
Features:
A) normal sw N-MOS 6502 behaviour (as 8501, illegal opcode included)
B) The I/O bits are at right places: the self-turbo routines (loaders) will work
C) R/W line is put on 3state and HOLD like as 8501 timings spec
D) TBC technique applied to help the CPU, even in the "worst case", to match the correct bus timings
E) the 2 bytes ram under the CPU port will be not corrupted (on C16 they are reachable by their mirrored address)
F) (*) each 6502 (which you will already find included in the CPU replacement) are selected for 2 specs:
---1) it has to be an N-Mos,
---2) it has to match to the specifics bus timings
Remember that N-MOS 6502 chips are discontinued,
often on market the sold chips are refurbished and relabelled with a label different to the old one:
chips marked as "6502" may not be N-Mos as it have to be, and vice versa (C-MOS, so no execution of the illegal opcode).
I found a chip labelled as "W65C02S" (10MHz C-MOS) that is a 1MHz N-MOS, and some of not working chips marked as "MOS6502A" seem to be MC6809 Cpu...
This mod will be assembled on request, also on sale elsewhere.
The cost:
29€+untracked shipping cost: PPal "FOR FRIENDS" (I can't be responsible for untracked shipping)
29€+tracked shipping cost (+ eventual PPal fees if PPal "COMMERCIAL" )
PM me about the price of small lots of my different items
Other projects for C16 PLUS4 and combined shipping available.
For CPU4PLUS4: please declare whether U4 is soldered onto your motherboard or whether it is on a socket.
-If U4 is on the socket, it takes up more vertical space and CPU4PLUS4 needs to be assembled with high pins and consequently the 6502 chip must be soldered directly onto it.
-If U4 is soldered on the motherboard, it takes up less vertical space, and CPU4PLUS4 can be assembled with short pins and the 6502 chip can be placed on a socket.
For more details contact me via PM,
thanks
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