MIT PDP-10 'Info' file converted to Hypertext 'html' format by Henry Baker
Symbols particular to this file:
- # means "not equal".
- <= means "less than or equal".
- >= means "greater than or equal".
- <- means "is assigned the new value".
Symbols which are taken from assembler language:
- AC means the contents of the AC field of the current instruction;
this is a number from 0 to 17.
- E means the value of the effective address of the current instruction.
*Note Addr: Addr-Comp, for how this is computed.
- PC means the address from which the next instruction will be fetched.
- C(...) surrounding an expression refers to the contents of the memory
location whose address is the value of the expression.
Thus, C(AC) is the contents of the accumulator which the
instruction refers to, and C(E) is the contents of the memory
location which the instruction refers to.
- CR(...) means the right half, only, of the contents.
- CS(...) means the contents, wit the two halves swapped.
- CL(...) means the left half, only, of the contents.
- x,,y means a word whose left half contains x, and whose right half
contains y. This is similar to x*1000000+y, except that x,,y
truncates y, using only the low 18 bits of it.
- <...> surrounding an expression serves the same purpose
as parentheses in algebra. Thus, 5*<1,,1> equals 5,,5.
- [...] surrounding an expression means the address of a word
in memory which contains the specified expression.
Thus,  means the address of a word containing 2.
This is called a literal. The address could turn out to
be anything at all, but the proper ways to use literals are
such that only the contents matter.
- (...) surrounding an expression exchanges the halves of that
expression. Thus, (3,,4) equals 4,,3.