register-impoverished childhoods was Re: Z80 TRAP and CP/M

Tony Duell ard at p850ug1.demon.co.uk
Wed Apr 5 18:18:32 CDT 2006


> 
> > E.g., if you are writing code for a 68xx, you have little choice
> > but to do everything in memory addressing.
> 
> Or a 6502. I don't know what to *do* with all the other registers on
> other architectures. ^_^;;

For the exact opposite, look at the PERQ 1a at the microcode level. 256 
general-purpose registers (each 20 bits wide). There's even an 8 bit 
register which can be used to select a particular register -- that is 
you have a sort of indirect addressing to the registers.

-tony



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