It's very late, I've spent a lot of time trying to make that thing work,
but... it doesn't!
This is how I connected the whole thing: (sorry, didn't find time to draw
a schematic, and I have no dedicated software. Do you know good, open-source ones?)
- not connected:
A4-A15 (I only watch A0-A3)
/HALT,/MREQ,/IORQ, /RD, /WR, /BUSAK, /M1, /RFSH
- to Arduino 5V :
Vcc, /INT, /NMI, /WAIT, /BUSRQ
- to GND:
- to arduino:
CLK, /RESET, A0-A3
When I power this on, without any resistor before GND, the CPU overheats
very fast (even if I clock the CPU at 1 Hz... it seems strange to me), and I unplug
it 'cause I'm not sure it won't break.
If I use a resistor, it takes time to heat, but enventually will. And it doesn't work the same.
My sketch is the following :
set arduino clk & reset to output, arduino A0-A3 to input
reset <- low
clock <- low
every 500 ms, switch the clock output from low to high or high to low
after 3 s, reset <- hi
read A0-A3. if result is different than previously read, display.
When I use a resistor, I've got a fixed 1111 result from A0-A3.
When I don't, it alternates very quickly between 1111 and 0111. (faster
than the clock). But I didn't think of MREQ, maybe I have to check its
value too before displaying A0-A3.
So, still I'm stucked... but I go on searching.
BTW, Rob, thanx for the http://www.z80.info
website, I think I will try to
setup the minimum Z80 CPU test circuit (http://www.z80.info/z80test0.htm
seems a good way to find if the CPU is still OK, and if there is any problem with
Time to sleep, I will just try the MREQ thingy before (or I won't be able to sleep!). See ya.