First PCBs arrived

A project log for 1 Square Inch TTL CPU

A microprocessor built with TTL chips. In one square inch.

roelhroelh 09/21/2018 at 18:052 Comments

Top and bottom side of the square inch PCB. Compare the size to an antique 8085 CPU ! The 1.27 mm header is very tiny, never used that before....

You might have noticed that the last hole on both the headers has no pad around it. Reason is, that with a pad, the pads would come too close to the border of the PCB, according to the design rules of the PCB manufacturer. So I removed the pad there, but the hole is still there, and the headers are placed a little bit out of center so the pad at the other side has enough space. The pins must be connected to a nearby pad with a small wire. For pin 1 (VCC) this connects to C2 (lower left side on bottom), and for pin 40 it connects to a dummy-resistor very close to it (upper right side on top).

Unfortunately, the bigger support pcb's are delayed, and will come after the weekend...


Dave's Dev Lab wrote 09/21/2018 at 18:28 point

love it!

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roelh wrote 09/21/2018 at 18:44 point

Yes they look cute !

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