Name        Number  Description                             Arguments
----------  ------  -------------------------------------   --------------------------
LIT            $00  Load constant                           3-byte literal (number)
STACK          $01  Alter runtime stack to address          2-byte stack address
NEG            $02  Negate (sp)                             none
LIB_CALL       $03  Call library function/procedure         absolute address
ADD            $04  Add (sp) to (sp - 1)                    none
SUB            $06  Subtract (sp) from (sp - 1)             none
MUL            $08  Multiply (sp) * (sp - 1)                none
DIV            $0A  Divide (sp - 1) / (sp)                  none
MOD            $0B  Modulus (sp - 1) MOD (sp)               none
ADRNN          $0C  Address of integer                      level, displ
ADRNC          $0D  Address of character                    level, displ
ADRAN          $0E  Address of integer array                level, displ
ADRAC          $0F  Address of character array              level, displ
EQL            $10  Test (sp - 1) == (sp)                   none
FINISHD        $11  Stop run (end program)                  none
NEQ            $12  Test (sp - 1) != (sp)                   none
LSS            $14  Test (sp - 1) < (sp)                    none
GEQ            $16  Test (sp - 1) >= (sp)                   none
GTR            $18  Test (sp - 1) > (sp)                    none
LEQ            $19  Test (sp - 1) <= (sp)                   none
ORR            $1A  OR  (sp - 1) | (sp)                     none
AND            $1B  AND (sp - 1) & (sp)                     none
INP            $1C  Input number                            none
INPC           $1D  Input character                         none
OUT            $1E  Output number                           none
OUTC           $1F  Output character                        none
EOR            $20  Not (sp) (logical negate)               none
OUH            $21  Output hex number                       none
SHL            $22  Shift left (sp) bits                    none
OUS            $23  Output string                           length, string
SHR            $24  Shift right (sp) bits                   none
INS            $25  Input string into array                 max, level, displ
INC            $26  Increment (sp) by 1                     none
CLL            $27  Relative procedure/function call        level, relative address
DEC            $28  Decrement (sp) by 1                     none
RTN            $29  Procedure/function return               none
MOV            $2A  Copy (sp) to (sp + 1)                   none
CLA            $2B  Call absolute address                   none
LOD            $2C  Load integer onto stack                 level, displ
LODC           $2D  Load character onto stack               level, displ
LDA            $2E  Load absolute address integer   (MEM)   none
LDAC           $2F  Load absolute address character (MEMC)  none
LDI            $30  Load integer indexed                    level, displ
LDIC           $31  Load character indexed                  level, displ
STO            $32  Store integer                           level, displ
STOC           $33  Store character                         level, displ
STA            $34  Store integer absolute address   (MEM)  none
STAC           $35  Store character absolute address (MEMC) none
STI            $36  Store integer indexed                   level, displ
STIC           $37  Store character indexed                 level, displ
ABSCLL         $38  Absolute procedure/function call        level, absolute address
XOR            $3A  XOR (sp - 1) ^ (sp)                     none
INT            $3B  Increment stack pointer                 increment
JMP            $3C  Jump unconditionally                    relative address
JMZ            $3D  Jump if (sp) zero                       relative address
JM1            $3E  Jump if (sp) not zero                   relative address
ABS            $3F  ABS (absolute value of (sp))            none
OUTCR          $40  Output a carriage-return                none
LCD_WRITE_NUM  $42  Write number to LCD                     none
LCD_WRITE_STR  $43  Write string to LCD                     none
LCD_WRITE_HEX  $44  Write hex number to LCD                 none
LCD_WRITE_CHR  $45  Write character to LCD                  none


Note: There are some gaps.

0x80 to 0xFF - Load low literal (onto stack), where literal is P-code with 8-bit clear (ie. P-code & 0x7F)
This is used instead of LIT if the number to be pushed onto the stack is in the range 0x00 to 0x7F.

The opcodes with no arguments generally pull their argument from the stack, or in some cases, two arguments.
For example ADD pulls the top two elements from the (runtime) stack, adds them together, and pushes the result.