BigEd wrote:
Are we talking about converters on the '22s interface to the micro, or the external-facing interface?
Either way, level shifting ICs are readily available, which handle 8 (or more) signals in one chip.
Not sure I understand your terminology, but the application would be a small PCB that plugs in where the NMOS 6522 fits in the 1541. As such, all pins that are defines as inputs (RESET, PHI, PORTA, PORTB, etc.) would need some help to ensure a high level is 4V, not just 2V as specified by the NMOS 6522 and the 65C22N
As I noted for current mirrors, level shifters are nice...
Quote:
but could add significantly to the parts quantity and/or board real estate.
Which is my main concern. In this application, I may need to put a small CPLD, a 65C22S, a 75160, and a 75161. And, all of it needs to fit in the DIP40 footprint. Putting passive level shifters on PORTA, PORTB, and all the ancillary input lines like PHI, RESET, and C*[12] lines that need it would be 3 addition TSSOP20s, at least. I don't think all of that will fit on a 40 pin footprint.
Jim