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Instruction Set.md

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Instruction Set

Flix-16, a 16-Bit CPU capable of basic operations.


Important

Append each ALU operation with a NOP!

So instead of

0a 01 00
do
0a 01 00 00 00 00

The CPU has no stack, so no subroutines / functions.



Flags

Flag Set if ALU operation result
CF caused a carry out
VF overflowed
NF was negative
ZF was zero


Instructions

Processor instruction mappings.


Info

Instruction Value
IMM := 0000 - ffff Immediate Value
RAM := 0000 - ffff RAM Address
REG := 00 - 02 Register-ID (00 = A, 01 = B, 02 = C)
ADDR := 0000 - ffff ROM Address

Miscellaneous

Instruction Machine Code Description
NOP 00 00 00 No operation
HLT 15 00 00 Waits until INT1 is pulled high

Loading

Instruction Machine Code Description
LDAI 01 XX XX Load A with immediate XX XX
LDBI 02 XX XX Load B with immediate XX XX
LDCI 03 XX XX Load C with immediate XX XX

Instruction Machine Code Description
LDAR 04 XX XX Load A with RAM XX XX
LDBR 05 XX XX Load B with RAM XX XX
LDCR 06 XX XX Load C with RAM XX XX

Storing

Instruction Machine Code Description
STA 07 XX XX Store A in RAM XX XX
STB 08 XX XX Store B in RAM XX XX
STC 09 XX XX Store C in RAM XX XX

ALU

Instruction Machine Code Description
ADD 0A XX XX RA + RB ➞ RB
SUB 0B XX XX RA - RB ➞ RB
AND 0C XX XX RA & RB ➞ RB
OR 0D XX XX RA | RB ➞ RB
NOT 0E XX XX ~RA | ~RB ➞ RB
XX must be constant.
NOR 0F XX XX ~RA | ~RB ➞ RB
NAND 10 XX XX ~RA & ~RB ➞ RB
XOR 14 XX XX RA ^ RB ➞ RB

Jumps

Instruction Machine Code Description
JMP 11 XX XX Jump to XX XX on next cycle
JZ 12 XX XX Jump to XX XX on next cycle if ZF is set
JN 13 XX XX Jump to XX XX on next cycle if NF is set
JNZ 18 XX XX Jump to XX XX on next cycle if ZF is NOT set

IO

Instruction Machine Code Description
IN_C 16 Load C with data on the input bus
OUT_C 17 Output C on the output bus

Bit Shifting

Instruction Machine Code Description
LSL1 19 XX XX Logical shift left by 1
XX must be constant.
LSR1 1A XX XX Logical shift right by 1
XX must be constant.


128 x 128 Display Driver

Instruction Machine Code
NOP 0000 0000 0000 0000
LDX 0000 0000 0000 0001
LDY 0000 0000 0000 0010
DATA / PLOT 0000 0000 0000 0011