On 4/27/2018 4:10 PM, Mia Magnusson wrote: > > In the 6509 replacement thread I think Jim got stuck at a point where > a nmos 6502 works but a cmos 65C02 doesen't work. "stuck" might be too strong a word. I noticed it did not, and I needed to do the board rev, so I quit debugging until the new baords came. They have arrived, and I can drag it out and test. > That needs to be > investigated. If a 65C02 could be made to work, it would be good to > check if any existing software uses illegal op codes or similar. If > not, a 65816 might be a good idea. In it's 6502 emulation mode it could > use the same kind of registers as the 6509 to access all 1MB ram, but > in the full 65816 mode it could access all ram in it's native way. I am sure it will work, and an '816 as well. Happy to help with CPLD work. > Also I'm not sure that everyone interested in a replacement board > actually wants one that fits an existing B series case. I certainly > don't want that as I haven't got any B series machine. But as long as > we don't almost run out of space on the board, it could probably be > edited to fit various physical form factors if that would be wanted. > > Btw, are the 6551 compatible enough with a 6850? If not, what differs? A lot > > Which software uses the 6551? > > One thing I would really like to have is hardware that can remap > various stuff so it could emulate a PET too. I am confident that the board can be as small as the DIP ICs (6509/6502, 6551, 6525, 6525, 6526, 6581, 6845) + a tqfp144, a TSOP44 FLASH and a TSOP48 2MB SRAM + connectors. But, at that size, the DIP ICs then dominate the board. The obvious next step is to move the '25,'25,'26,and '02/816 into progrmamable logic, but you're into FPGA land then. Then, the 6845 and the 6551 are moving, and the resulting board would be a CPLD (buffers for the FPGA), FPGA, FPGA ROM, ROM, RAM, SID, connectors. I think that leaves 2 options: DIP parts/CPLD/RAM/FLASH, or Full FPGA/RAM/FLASH/SID... JimReceived on 2018-04-28 06:00:02
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