Ciarciaʼs Circuit Cellar
Byte Magazine, May 1984

Trump Card -

Circuit sections

Notes: One 100n decoupling capacitor on each IC. N/C denotes No Connection.


Clock and Reset

The Z8515 chip might be hard to get hold of. It does some kind of complex clock-stretching.

ADD2 adds two wait states.

Most of the chips features are unused. I think the CPU clock could be managed much like the clock stretcher in the 6502 design.


CPU

The Z8000


Simple.

Status decoder

Simple.


Glue

Trump Card glue - ADD2 logic

Adds wait states for slow memory.


Trump Card glue - PC A0 buffer


Trump Card glue - reset generator


Trump Card glue - PC select decoder


Complementary phi clocks

Simple.


Trump Card glue - 1a


Trump Card glue - 1b


Trump Card glue - 2a


Trump Card glue - 2b


Trump Card glue - 2c


Trump Card glue - 3


Trump Card glue - NMI generator


Trump Card glue - incrementer


Interprocessor communications

Quite clever, uses 2K RAM and a '393 counter for the address lines.

2K RAM letterbox


ROM 2K by 16 bit

Simple.


DRAM

DRAM is easily replaced by SRAM these days.