True, a shift register may be all you can get.? Making a counter can be more difficult because you may not have access to the preset lines on the flipflops.
I skipped from the 22V10 directly to CPLDs.? I had designs that I couldn't do in PALS.
Harvey
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On 2/22/2022 3:14 PM, Dave McGuire wrote:
On 2/22/22 14:04, Harvey White wrote:
PALs are combinational logic, such as (using address lines)? A4 and A3 and not A2 and A1 and not A0.
To decode serial data, you need flip-flops, some storage to convert serial to parallel and then act on that.
CPLD's can do that, but with most PAL chips, depending on what's internal, it would be difficult.
Generally, PALs are used to decode address lines to enable a specific chip.
? No.? The very earliest PALs, like PAL16L8 etc, are combinatorial. But shortly thereafter, 16R8 (etc), the 'R' meaning "Registered", appeared.? These are sequential logic devices that store state and have feedback terms.? Still later, the 16V8 etc, (the 'V' meaning "Variable" or "Versatile", depending on who you ask) have still greater functionality.? It's easy to implement something like a shift register using PALs and nothing else.
???????????? -Dave
