Current NEWT technical manual.

Thoughts on the NUT CPU.

The replacement CPU board ready to be debugged.

The replacement CPU board reverse side.

The NEWT fetches its first instruction!

Register memory is automatically mapped to the internal 16-bit RAM.
This is a register write. Notice the register address read and
write at the beginning of the sequence. The register address is
stored in RAM so that it is preserved during power-down.

Register memory read.
The register address in RAM is automatically modified by this
instruction.

LDI instruction execution.

JSB with auto-return because the first instruction is a NOP.

Entering 50x turbo mode.
Notice how fast the program counter is incrementing in turbo mode.

Executing in 50x turbo mode.
The cursors mark one instruction time. At 50x it's slightly longer than
the time for one regular Nut clock cycle.

Automatic fall-back to 1x.
The instruction is checking the keyboard flag. The NEWT waits for the
dummy external bus cycle to complete, and then executes the CHK KB
instruction at regular speed. It then resumes 50x execution.

Automatic re-fetch of instruction in 1x.
This is an ENROM1 instruction being automatically re-fetched and
executed in 1x speed so that it will be seen on the external bus.
Both the fetch and execute are done at 1x, and then turbo resumes.

Current instruction set testing status.