The machine instruction sets are (almost by definition) different on each machine where `as' runs. Floating point representations vary as well, and `as' often supports a few additional directives or command-line options for compatibility with other assemblers on a particular platform. Finally, some versions of `as' support special pseudo-instructions for branch optimization.
This chapter discusses most of these differences, though it does not include details on any machine's instruction set. For details on that subject, see the hardware manufacturer's manual.
| AMD29K-Dependent | AMD 29K Dependent Features |
| Alpha-Dependent | Alpha Dependent Features |
| ARC-Dependent | ARC Dependent Features |
| ARM-Dependent | ARM Dependent Features |
| CRIS-Dependent | CRIS Dependent Features |
| D10V-Dependent | D10V Dependent Features |
| D30V-Dependent | D30V Dependent Features |
| H8/300-Dependent | Hitachi H8/300 Dependent Features |
| H8/500-Dependent | Hitachi H8/500 Dependent Features |
| HPPA-Dependent | HPPA Dependent Features |
| ESA/390-Dependent | IBM ESA/390 Dependent Features |
| i386-Dependent | Intel 80386 and AMD x86-64 Dependent Features |
| i860-Dependent | Intel 80860 Dependent Features |
| i960-Dependent | Intel 80960 Dependent Features |
| M32R-Dependent | M32R Dependent Features |
| M68K-Dependent | M680x0 Dependent Features |
| M68HC11-Dependent | M68HC11 and 68HC12 Dependent Features |
| M88K-Dependent | M880x0 Dependent Features |
| MIPS-Dependent | MIPS Dependent Features |
| MMIX-Dependent | MMIX Dependent Features |
| SH-Dependent | Hitachi SH Dependent Features |
| SH64-Dependent | Hitachi SH64 Dependent Features |
| PDP-11-Dependent | PDP-11 Dependent Features |
| PJ-Dependent | picoJava Dependent Features |
| PPC-Dependent | PowerPC Dependent Features |
| Sparc-Dependent | SPARC Dependent Features |
| V850-Dependent | V850 Dependent Features |
| Z8000-Dependent | Z8000 Dependent Features |
| Vax-Dependent | VAX Dependent Features |