cbscpe wrote:
At mouser the small CPLD ATF1504 and a W65C51 cost together about 12 swiss franks and the larger CPLD ATF1508 costs 8 swiss frank. I know that the receiver and the transmitter with buffering fits in a ATF1508 (i have done this and the design requires about 70 flipflops). Whether all the other features still fit in the ATF1508 I need to check. But if you can live without modem control signals (and honestly who does need them nowadays) it should not be a problem and as the ACIA only requires very few pins you can use the rest of the pins to build your address decoder. a address decoder typically requires alot of pins but very little CPLD resources. In other words they complement each other perfectly.
If we can stuff the 6551 the registers into a 128 macrocell CPLD, I'm game. The 6551 requires at least 48 registers to operate, as far as I can tell (8 for XMIT + 8 for buffer, 8 for RECV + 8 for buffer, 8 for COMMAND + 8 for CONTROL). I suspect the status flags take some as well.
But, if I could get it into a 128 or even a 256 macrocell CPLD, I'd be happy to try.
Jim
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