GAL 1.0 - Assembly Language Playground

New to GAL? Read the introduction or the user manual, or try the exercises.

; FizzBuzz, 1 to 100, printing one item per line
; count from 1 to 100 replacing any number that is divisible by 3 with the word Fizz,
; any number that is divisible by 5 with the word Buzz, and any number divisible by
; both 3 and 5 with FizzBuzz

LOOP:     LOD N           ; N = N + 1
          INC
          STO N
          SUB LIMIT
          JGZ DONE        ; stop once N > 100

CLR
          STO FLAG        ; FLAG = 1 if Fizz or Buzz gets printed

LOD N
          MOD 3           ; modulo divide by 3
          JNZ NOFIZZ
          LOD 70          ; F
          PRC
          LOD 105         ; i
          PRC
          LOD 122         ; z
          PRC
          LOD 122         ; z
          PRC
          LOD 1
          STO FLAG

NOFIZZ:   LOD N
          MOD 5           ; modulo divide by 5
          JNZ NOBUZZ
          LOD 66          ; B
          PRC
          LOD 117         ; u
          PRC
          LOD 122         ; z
          PRC
          LOD 122         ; z
          PRC
          LOD 1
          STO FLAG

NOBUZZ:   LOD FLAG
          JNZ NEWLINE     ; a word was printed, so skip the number
          LOD N
          PRN

NEWLINE:  LOD 10         ; new line character
          PRC
          JMP LOOP

DONE:     HLT

N:        DAT 0
LIMIT:    DAT 100
FLAG:     DAT 0

dump data cells after runningAfter the program halts, list every data cell and its value

ACC: 0The accumulator: the lights show its lowest 16 bits; the decimal value is always exact

PC : 0The program counter: the number of the next instruction to run, counting from 0 (ignoring comments, labels and DAT lines). The lights show its lowest 8 bits

HALT: The HALT light shows dark: not finished, amber: halted correctly, red: program error

Instruction set

CLR	clear the accumulator
LOD	load the accumulator from a cell or with a constant
STO	store the accumulator into a data cell
ADD	add a cell or constant to the accumulator
SUB	subtract a cell or constant from the accumulator
INC	add 1 to the accumulator
DEC	subtract 1 from the accumulator
NEG	negate the value in the accumulator
MUL	multiply the accumulator by a cell or constant
DIV	divide the accumulator by a cell or constant
MOD	modulo divide the accumulator by a cell or constant
RDN	read a number into the accumulator (error if no number remains)
RDC	read the next character into the accumulator (0 when input ends)
PRN	output the accumulator as a number
PRC	output the accumulator as a character
JMP	jump to a code label
JEZ	jump to a code label if the accumulator is zero
JNZ	jump to a code label if the accumulator is not zero
JLZ	jump to a code label if the accumulator is less than zero
JGZ	jump to a code label if the accumulator is greater than zero
HLT	stop execution
NOP	do nothing
DAT	declare a data cell (label required), e.g. FOO: DAT 10