Version E

A project log for One Bit CPUs

I have been exploring one bit CPUs. For the right application they may be worth knowing.

agp.cooperagp.cooper 09/15/2017 at 14:000 Comments

Version E of the One Bit CPU

I updated the schematic and the PCB of the One Bit CPU.

  1. I fixed up the two schematic errors.
  2. Removed the single step (does not work that well)
  3. Reworked the clock circuit
  4. Removed some redundant circuity

Hers is the updated schematic:

Here is the test program:

Spend a few moments to see that DOUT, IO and IO ADDR are merged into one byte.

Th high address (or page) is ADRH.

The low address is either LOW or HIGH depending on the value of DIN (the read value from the selected input).

Each instruction (PC ADDR or ADR) is four bytes, therefore when using a 32k flash ROM it has 8k program space.

You may see that the One Bit CPU is basically a Finite State Machine (FSM).

Demo Program

A demo program needs to do something visual. So I coded a binary counter:

But for this to work all the shunts have to be moved from switch to memory:

With the clock set at 10Hz, it now slow counts away the day.