Finally - A CPU

A project log for 555ENabled Microprocessor

A Microprocesser made in a digital logic family based on the NE555

TimTim 12/11/2021 at 13:450 Comments

Finally, now that everything came together for the NE555 logic flow, we can use it on an actual microprocessor. Above, you can see the result of synthesizing and placing the MCPU in NE555 logic. The MPCU is quite simple, it's an 8 bit CPU with only four instructions and optimized for small size.

Of course, any kind of discrete logic takes up a lot of PCB space and NE555 logic is a bit on the larger side. So even for this simple CPU we end up with a PCB that is about 200x200mm².

A 3D rendering out of EasyEDA above.

And one more.

The final microcell counts

ne_NOT      234
ne_WAND2     72
ne_WAND3     48
ne_TBUF      48
ne_WAND4     23
IO           20
__TBUF_       8

Total component usage

Component           Count
pin                 20
NE555               234
cap                 234
resistor            287
diode               380
npn transistor      48
------------------  -----
Total:              1203

I will not route and build the design for now, as I need to design a CPU testbed first. I have another NE555 design in preparation that I am planning to build first, but that will be in a different project.