PCPI clone assembly

[Alex Freed <alex_news@mirrow.com>]

A couple of people asked questions about assembling
my z80 board.

Q. Shoud R3 be 1k as on the schemaic diagram or 5.6K?
A. Definitely 5.6K. I have shipped *only* 5.6K resistor.
The oscillator may not be stable with 1K.
R7 could be anything from 0 to 100K.
Same is true for R8 if it is populated at all (trace cut).

Q. What happened to C4, C6, R1 and U7? I don't see any of them on the
circuit diagram or PCB silkscreen.
A. They just don't exist. Removed at a prototype stage.

Q. pcpi_intf.v shows logic dependent on the state of "HAVE_NMI" - does
the CPLD as shipped have support for generating a Z80 NMI?
A. Experiments show that NMI was never triggered while running CP/M.
So it was disabled. If you ever need it back to experiment with your
own code, you probably know how to re-program the CPLD.

-Alex.