Basic structure
Each line of assembly code can contain:
- An optional label (ending with
,)
- An instruction, directive, macro, or expression
- Comments (starting with
/)
LABEL, ADD 0R / This is a comment
SUB 1R / Instructions can be on lines without labels
Labels
Labels mark specific addresses in your program and must end with a comma:
START, / Label marking the start
JUN START / Jump to the START label
LOOP, / Another label
INC 0R
JCN NZ? LOOP
Labels are automatically assigned the .address type and can be used as jump targets or in expressions.
/ and continue to the end of the line:
/ This is a full-line comment
INC 0R / This is an end-of-line comment
Directives
Origin directive
Set the program counter to a specific address using the = directive:
= 256 / Set origin to address 256
= 0x100 / Same as above
The origin expression cannot contain labels. Only numeric values are allowed.
Equate directive
Define named constants using the name = value syntax:
EPB = 1 / End pointer bank
EPA = 0 / End pointer address
AS1 = 1 / First nibble of allocation start
KEYBOARD_PORT = 2 / Keyboard ready port
BUFFER_SIZE = 128
BUFFER_END = BUFFER_START + BUFFER_SIZE
Standalone data
You can embed raw data bytes using standalone numeric expressions:
DATA_SECTION,
'e' / Character literal
'c'
'h'
'o'
255 / Decimal number
0xAB / Hex number (if supported)
Whitespace
Whitespace (spaces and tabs) separates tokens but is otherwise ignored. Instructions and arguments can be formatted for readability:
FIM 0P 5 / Spaced for alignment
JMS PUSH_4 / Different spacing is fine
Decimal
Binary
Registers
Register pairs
Default format for numbers: Binary numbers end with B:LDM 1010B / Binary 1010 = 10 decimal
FIM 0P 11111111B
Registers end with R:ADD 0R / Register 0
XCH 15R / Register 15
Register pairs end with P:FIM 0P 42 / Register pair 0 (0R and 1R)
SRC 3P / Register pair 3 (6R and 7R)
Conditions
Conditions are used with jump instructions and end with ?:
JCN Z? LABEL / Jump if zero
JCN NZ? LABEL / Jump if not zero
JCN C? LABEL / Jump if carry
JCN NC? LABEL / Jump if not carry
Z? - Zero (accumulator is 0)NZ? - Not zeroC? - Carry setNC? - Carry not set
Character literals
Character literals are enclosed in single quotes:
FIM 0P 'A' / ASCII character A
FIM 0P ' ' / Space character
\n - Newline\t - Tab\a - Alert/bell\d - Delete\\ - Backslash\' - Single quote
FIM 0P '\n' / Newline character
FIM 0P '\\\\' / Backslash character
Special symbols
Current address (*)
The * symbol represents the current program counter:
*+14 -> 8R _ _ / Current address plus 14
JCN NC? *+4 / Skip ahead 4 bytes
Placeholder (_)
The underscore is used as a placeholder in source/dest expressions:
*+14 -> 8R _ _ / Write to 8R, skip two positions
128 -> 0R 1R 2R / Write to all three registers
Case sensitivity
Instructions, registers, and conditions are case-sensitive:
ADD 0R / Correct
add 0r / Incorrect
JCN NZ? / Correct
jcn nz? / Incorrect