z80 computer

I continued this project and built i/o controller.

You can use it with instructions such as IN and OUT.

Sorry for bad resolution.

ICs used are 4075-3input or gate , 4078 8 input or/nor gate and 74hc541 non inverting buffer.

Its connected to DB25 connector

Zilog80 is in housing now.

I have used wood, beacuse it looks nicer, than plastic.

Inside is 70VA transformer and on the backside there are doors for connectors.(with iluminating light bulb.

More photos later ...

This is simple z80 computer system.

It has no rom, but it has 8kbyte of static RAM.

If you will make this make shure, that you will use a lot of filtering caps on power supply line, to clean out ac high frequency noise.

The schematic is very simple.

Just z80, sram i/o devices and some logic stuff.

Here is the video, if you are interested, how it works.

This is the program:

Besedilno polje

3E LD A,n Loads number into register a

02 n, 2

C6 ADD A, n Adds number to register a

05 n, 5

32 LD (nn), A Loads register a into external memory.

0F n(15) lower 8 addres bits (a0-7)

00 n(0) uper 8 addres bits (a8-15)

76 HALT excutes halt command

When i will finish this computer i will make another design with 74hc541 and inverters, instead of 74HC125 and 74HC126.

This will make pcb smaller and thing cheaper.

I will add backup battery for RAM.

Z80 with AND instruction video.

Code

LD A, (n)

16 (n)

E6 AND, (n)

1C (n)

32 A, (nn)

FF (n) (lower 8bits)

00 (n) (upper 8bits)

76 HALT