A quarter hardware for a full computer

Here is a funny idea that just came to my mind, no plans for implementing it but, possibly, a way for saving cost and labor to a quarter.

The idea is this: I could redesign the whole architecture to be 4-bits internal, 16-bits external. All registers, ALU etc. 4-bits; internal buses, 4-bits too. External buses, however, are 16 bits, standing behind latches that patiently wait for the address or data to be completed.

All sequences run 4 times longer; for example, an arithmetic operation is done 4-bits at a time. A memory write cycle that normally takes 3 clock periods, now takes 12 (well, actually less than that) because the address must be collected into the bus latches, 4 bits at a time.

Would this computer run 4 times slower? Not necessarily: the clock speed can be increased 4 times! I've design Heritage/1 around a 4 MHz clock; now I would increase to 16 MHz (T=62 ns) which is still comfortable for HCMOS chips, although care would be needed for wiring due to electromagnetic issues.

There are two cool things about this architecture: (1) A tremendous cost cut, and (2) flexible configuration.

In fact: the machine can be designed to easily accommodate different configurations, that is different bus sizes: 8 bits for a character intensive machine, 16 bits for real time applications or modest general purpose computer, 32 bits for precision scientific applications... just to say.

I would call a machine like that: "Heritage-1/4".