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Re: [N8VEM-S100:1086] A new S-100 6502 CPU Board
"There has been some interest in using a WDC 65C816 processor in a system that was designed for a 6502.
However, the two are not pin for pin compatible. Some form of adapter is required.
With some suggestions from the users on the 6502 Forum, I created a working schematic for an adapter.
IC3 and IC4 are used to create the two-phased clock output PH1 and PH2 that the 65816 does not generate.
IC2 is used to keep the data bus at high-impedance during PH1."
On Wed, Aug 22, 2012 at 6:35 PM, Andrew Lynch <LYN...@yahoo.com>
Hi! Below is the circuitry from the ECB 6x0x host processor board which allows a single CPU board to use a 6502, 6809, or 6802 processor. As you can see the three processors are very similar and to make the accommodations requires an extra 40 pin socket and small number of jumpers and resistors. This works very well and several of the N8VEM ECB builders have 6x0x systems which can switch between the three processors at build time.
Thanks and have a nice day!