I found them to be very regular and understandable.
So when I encountered intel chips and their assembly syntax, I disliked them.
So about that time I switched to higher level languages.
Are there still chips left have a nice orthogonal assembly language? I vaguely recall 68k being orthogonal too.
ADD A,B ;8 bit add, B to A
ADD HL,BC ;16 bit add, BC to HL
ADD B,A ;invalid! destination can only be A or HL
ADC A,B ;add with carry
SBC A,B ;subtract with carry
SUB B ;subtract (A is implicit, same for AND,OR,XOR)
LD A,(HL) ;load A from memory at HL
LD B,(HL) ;load B from HL
LD A,(DE) ;load A from DE
LD B,(DE) ;invalid! must be reg=A or mem=(HL)
LD A,(var) ;load A from variable
LD HL,(var) ;load HL from variable
LD DE,(var) ;extra opcode byte, 4 cycles slower
LD B,(var) ;invalid! must be A or register pair
JP (HL) ;load PC with contents of HL register, NOT MEMORY!
EX DE,HL ;exchange DE with HL (no other registers allowed)
EX HL,(SP) ;exchange HL with top of stack (no other reg,mem allowed)
EX AF,AF' ;wtf were they thinking?
EXX ;should be EX BCDEHL,BCDEHL' for consistency :)I would just add SUB A, B (etc.) and call it a day.
edit: looks like the Z800 was an improved/orthogonalized (and pipelined!) extension of the Z80 that maintained software compatibility. And it looks like the SUB A, B format is supported by eZ80 assemblers, though A is still the only valid 8-bit accumulator.