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| author | Kartik Agaram <vc@akkartik.com> | 2018-07-24 16:06:43 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2018-07-24 16:06:43 -0700 |
| commit | d57d39cb3f867d6e33ffa8e4cdc7d0ca749cb75c (patch) | |
| tree | 1800345f57b37202c18218a78b1bb21496460a0f /subx/010vm.cc | |
| parent | 1faa9790960043f5fbad482cd4b2cf4a6c50efd8 (diff) | |
| download | mu-d57d39cb3f867d6e33ffa8e4cdc7d0ca749cb75c.tar.gz | |
4395
Diffstat (limited to 'subx/010vm.cc')
| -rw-r--r-- | subx/010vm.cc | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/subx/010vm.cc b/subx/010vm.cc index 81a8c12b..d2f39e90 100644 --- a/subx/010vm.cc +++ b/subx/010vm.cc @@ -1,4 +1,8 @@ //: Core data structures for simulating the SubX VM (subset of an x86 processor) +//: +//: At the lowest level ("level 1") of abstraction, SubX executes x86 +//: instructions provided in the form of an array of bytes, loaded into memory +//: starting at a specific address. //:: registers //: assume segment registers are hard-coded to 0 @@ -32,7 +36,7 @@ cerr << " registers\n"; :(before "End Help Texts") put(Help, "registers", "SubX currently supports eight 32-bit integer registers: R0 to R7.\n" - "R4 contains the top of the stack.\n" + "R4 (ESP) contains the top of the stack.\n" "There's also a register for the address of the currently executing instruction. It is modified by jumps.\n" "Various instructions modify one or more of three 1-bit 'flag' registers, as a side-effect:\n" "- the sign flag (SF): usually set if an arithmetic result is negative, or reset if not.\n" |