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daleking / Z80_Breakout_LED

Z80 LED Breakout Board for Mike (UNTESTED)
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Right 20 pins of J1 socket is *under* Z80 DIP #1

Open prlaba opened 3 years ago

prlaba commented 3 years ago

As designed, the 40-pin U7 socket for the Z80 chip covers the right 20 pins of the 40-pin J1 socket. If you want to add headers for those pins, you have to mount the header on the back of the board.

A cleaner design would be to shift the U7 DIP pins over slightly to the left, leaving enough room on the right for the right 20 pins of the J1 socket. That would allow mounting two 20-pin headers on each side of the Z80 U7 socket, with the header pins aligned with the Z80's pins.

daleking commented 3 years ago

Hey yeah I don't even know if this works - it was requested by someone so I whipped it up without too much thought. Adding headers wasn't a requirement - I think it was just for bling!

prlaba commented 3 years ago

I like the overall design, and it works well. I especially like that you "reversed" the LEDs for the Z80's active-low pins (so the LED lights when the pin is asserted/low).

Should you ever decide to redesign the board...

. Re-route the Z80's address and data lines so they're in order vertically on the board (A15 at the top, A0 at the bottom; D7 at the top, D0 at the bottom). Better yet, mount those LEDs horizontally, with A15/D7 on the left and A0/D0 on the right. Makes it much easier to read the current address and data values.

. Do the same to separate the Z80's input and output (status) control lines.

. Connect the J1 header lines to the 74HCT541 output pins instead of the Z80 pins. That would allow you to connect those lines to more devices without overloading the Z80.

. Provide separate +5V and GND holes for connecting power to the board.

. Move the location of the J1 header holes, so two 20-pin (female) headers can be mounted on the front side of the PCB.

Thanks,