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Board NEDONAND-3

A project log for NEDONAND homebrew computer

NEDONAND is 8-bit homebrew computer entirely built out of many 74F00 chips (2-input NAND gates)

SHAOSSHAOS 02/24/2016 at 02:251 Comment

NEDONAND-3 is 4-bit part of NEDONAND program counter that uses 2 board NEDONAND-2

Pins description (2 rows - male for inputs and female for outputs):

1.1) IN (OUT) - count enable
1.2) ACT0 - external writing signal "0"
1.3) ACT1 - external writing signal "1"
1.4) /RESET - master reset
1.5) CLK - clock signal
1.6) NC - not connected
1.7) VCC - power +5V
1.8) GND - ground

2.1) D0 - bit 0 for writing
2.2) D1 - bit 1 for writing
2.3) D2 - bit 2 for writing
2.4) D3 - bit 3 for writing
2.5) D4 - used in next stacked boards
2.6) D5 - used in next stacked boards
2.7) D6 - used in next stacked boards
2.8) D7 - used in next stacked boards
2.9) D8 - used in next stacked boards
2.10) D9 - used in next stacked boards
2.11) D10 - used in next stacked boards
2.12) D11 - used in next stacked boards (in case of 2K memory it's "0")

This board could be used as a single one for 16-byte program memory or as stacked together up to 3 (to use all 2048 bytes that is max by NEDONAND spec and D11 might be counter overflow flag):


Discussions

SHAOS wrote 02/25/2016 at 05:25 point

I forgot to mention that counted address should be taken from right 4-pin header (JP7):
3.1) A0
3.2) A1
3.3) A2
3.4) A3




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