ECB SBC Z180 mark IV / mk4
What a wonderful design! Has both SD card and IDE interface onboard, fast and easy to build. I love it!
Tips on U10:
I have just learned that when building this with all 74AHCT chips; the U10 (74ls38 NAND BUFFER) can be substituted with 74AHCT00 (NAND GATE), since the specs for the AHCT variant of the '00 exceeds the driving capacity of the '38 by +5mA. (I have not found a single 74AHCT38 for sale anywhere)
U10 has 4 NAND's, but only 3 are used in this design;
* U10A=/CS (Card Select of the SD card)
* U10B=Activity LED driver
* U10C=/INT2 signal to CPU on pin 12.
I have tested it for a week now and it seems to work fine with several SD card types, RomWBW 3.0.1 (with 2 custom config; supercap charge set on and activate PropIO v2 on boot)
I have not tested the MAX3467 / RS-422 yet.
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Built with 74LS chips and 18.322Mhz 1x CPU clock | ![]() |
Built with 74AHCT chips and 18.322Mhz 2x CPU clock | ![]() |
U10 seems to be ok with a 74AHCT00 | ![]() |