User`s manual

One-Line Assembler/ Disassembler
4-11
4
Refer to Chapter 5, System Calls, for information on the system call routines.
Entering and Modifying Source Programs
User programs are entered into the memory using the one-line
assembler/ disassembler. The program is entered in assembly
language statements on a line-by-line basis. The source code is not
saved as it is converted immediately to machine code upon entry.
This imposes several restrictions on the type of source line that can
be entered.
Symbols and labels, other than the defined instruction mnemonics,
are not allowed. The assembler has no means to store the associated
values of the symbols and labels in lookup tables. This forces the
programmer to use memory addresses and to enter data directly
rather than use labels.
Also, editing is accomplished by retyping the entire new source
line. Lines can be added or deleted by moving a block of memory
data to free up or delete the appropriate number of locations (refer
to the BM command in Chapter 3).
Invoking the Assembler/Disassembler
Use either the MM command or the AS command for program
entry and modification.
MM ADDR ;DI
or
AS ADDR
When either the MM or AS command is used, the memory contents
at the specified location are disassembled and displayed. A new or
modified line can be entered if desired. The disassembled line can
be a PowerPC instruction or a WORD directive. If the disassembler
recognizes a valid form of some instruction, the instruction will be
returned; if not (random data occurs), the WORD $XXXXXXXX