68k homebuilts

[Chuck Guzis]

On 12 Dec 2008 at 14:31, bfranchuk at jetnet.ab.ca wrote:


> That is 3 opcode bits  and a indirect bit. Going to 4 opcode bits
> gives you 32K of memory and would make a nice small machine
> that dates around the early 60's.
> 
> The problem is that I want to have local function variables, and that 
> requires

I suppose that a 16-bit (or 20-bit 3-(16/32 register) address design 
would be too complex.  But it would give you the flexibility you need 
without an explicitly-implemented hardware stack.  Make one of the 
registers PC and branches get interesting.

Who needs registers or indirect addressing anyway?  IA was an 
*option* on the CADET.    Instruction modification was a way of life.

Cheers,
Chuck