I am looking for a 9 bit computer.
Is it posible to expand the My4th design to 9 bits, using 9 bit rather than 8 bit parts. I know at one time they had 9 bit D flip/flops,and 9 bit ram/rom?.(8 data + parity)
A Cmos 22V10 can be programmed to the 9 bit D flip flops, a vaild subsitute
to replace a older TTL part.
The advantage here is that you now can have bit #9 select NOR or XOR.
You might cheat and have NOR/XOR/toggle ( 2 bits ) as 9 bit alu on the input to the data register. Dieter (TAF) for a 2 stage adder using J/K flip flops.
The other advantage is you now have a 18 bit ALU, giving a huge address
space for a simple computer. (I favor 18 bits so you can have a 36 bit float).
The instruction reg still can stay at 8 bits.
Pascal and other languages (BCPL) used P-style code for a Virtual Machine.
Time proved that 8 bits was too small a data size to do useful work.
CP/M needed 48Kb of ram just to run many programs ( Small c for example).
Having up to 256kb of ram may have other retro projects develop.
In my case revising the My4Th computer is just too complex
to get both the hardware/pcb lay out and microcode debugged
to run right from the first version of the new hardware.
Ben.
PS: MyNor might be better a option, as general purpose machine.
It is amazing how many chips just vanished with the Covid Lockdown.
74Fxxx had a 9 bit buffer and a 9 bit D F/F that was around until a few
years ago.