3 ms·

I learned ibm 370 assembly first, PDP-11 assembly second, then I think Z80. I found them to be very regular and understandable. So when I encountered intel ch

by m463 2y ago

I learned ibm 370 assembly first, PDP-11 assembly second, then I think Z80. 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.

clausecker 2y ago
ARM is pretty orthogonal, though arm64 is less so. RISC-V is very orthogonal, but it sucks to program for it in assembly as the instruction set is missing even basic features.
rep_lodsb 2y ago
Sorry, but Z80 being "regular and understandable"? 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 :)
- musicale 2y ago
  JP (HL) seems to be a disambiguator vs. JP HL (jump to label HL) and the register swap instructions, while quirky, seem justifiable as well. 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.
- m463 2y ago
  I remember the Z80 in relation to the 8080. I might have misremembered but I thought Z80 allowed some combinations that 8080 could not do. It could also be that the assembler/syntax itself was nicer.

by m463 2y ago

clausecker 2y ago

ARM is pretty orthogonal, though arm64 is less so. RISC-V is very orthogonal, but it sucks to program for it in assembly as the instruction set is missing even basic features.

rep_lodsb 2y ago

Sorry, but Z80 being "regular and understandable"? 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 :)

musicale 2y ago
JP (HL) seems to be a disambiguator vs. JP HL (jump to label HL) and the register swap instructions, while quirky, seem justifiable as well. 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.
m463 2y ago
I remember the Z80 in relation to the 8080. I might have misremembered but I thought Z80 allowed some combinations that 8080 could not do. It could also be that the assembler/syntax itself was nicer.