Opcodes for the 9x8 micro controller

Copyright 2012, 2014, Sinclair R.F., Inc.

This document describes the opcodes for the 9x8 micro controller. The first section lists the opcodes in alphabetic order, the second lists them by their numerical value, and the final section describes each one in detail.

Some of the opcodes are not directly accessible by the assembler and must be accessed through macros. See macros for documentation on accessing these opcodes. Other opcodes can be directly accessed or can be accessed through a macro.

OPCODES

This section documents the opcodes.

Alphabetic listing: &, +, +c, -, -1<>, -1=, -c, 0<>, 0=, 0>>, 1+>, 1->, 1>>, <<0, <<1, <<msb, >r, ^, call, callc, drop, dup, fetch, fetch+, fetch-, inport, jump, jumpc, lsb>>, msb>>, nip, nop, or, outport, over, push, r>, r@, return, store, store+, store-, swap

Opcode Mapping

Opcode	8	7	6	5	4	3	2	1	0	Description
nop	0	0	0	0	0	0	0	0	0	no operation
<<0	0	0	0	0	0	0	0	0	1	left shift 1 bit and bring in a 0
<<1	0	0	0	0	0	0	0	1	0	left shift 1 bit and bring in a 1
<<msb	0	0	0	0	0	0	0	1	1	left shift 1 bit and rotate the msb into the lsb
0>>	0	0	0	0	0	0	1	0	0	right shift 1 bit and bring in a 0
1>>	0	0	0	0	0	0	1	0	1	right shift 1 bit and bring in a 1
msb>>	0	0	0	0	0	0	1	1	0	right shift 1 bit and keep the msb the same
lsb>>	0	0	0	0	0	0	1	1	1	right shift 1 bit and rotate the lsb into the msb
dup	0	0	0	0	0	1	0	0	0	push a duplicate of the top of the data stack onto the data stack
r@	0	0	0	0	0	1	0	0	1	push a duplicate of the top of the return stack onto the data stack
over	0	0	0	0	0	1	0	1	0	push a duplicate of the next-to-top of the data stack onto the data stack
+c	0	0	0	0	0	1	0	1	1	push the carry bit from N+T onto the data stack
-c	0	0	0	0	0	1	1	1	1	push the carry bit from N-T onto the data stack
swap	0	0	0	0	1	0	0	1	0	swap the top and the next-to-top of the data stack
+	0	0	0	0	1	1	0	0	0	pop the stack and replace the top with N+T
-	0	0	0	0	1	1	1	0	0	pop the stack and replace the top with N-T
0=	0	0	0	1	0	0	0	0	0	replace the top of the stack with "`0xFF`" if it is "`0x00`" (i.e., it is zero), otherwise replace it with "`0x00`"
0<>	0	0	0	1	0	0	0	0	1	replace the top of the stack with "`0xFF`" if it is not "`0x00`" (i.e., it is non-zero), otherwise replace it with "`0x00`"
-1=	0	0	0	1	0	0	0	1	0	replace the top of the stack with "`0xFF`" if it is "`0xFF`" (i.e., it is all ones), otherwise replace it with "`0x00`"
-1<>	0	0	0	1	0	0	0	1	1	replace the top of the stack with "`0xFF`" if it is not "`0xFF`" (i.e., it is not all ones), otherwise replace it with "`0x00`"
return	0	0	0	1	0	1	0	0	0	return from a function call
inport	0	0	0	1	1	0	0	0	0	replace the top of the stack with the contents of the specified input port
outport	0	0	0	1	1	1	0	0	0	write the next-to-top of the data stack to the output port specified by the top of the data stack
>r	0	0	1	0	0	0	0	0	0	Pop the top of the data stack and push it onto the return stack
r>	0	0	1	0	0	1	0	0	1	Pop the top of the return stack and push it onto the data stack
&	0	0	1	0	1	0	0	0	0	pop the stack and replace the top with N & T
or	0	0	1	0	1	0	0	0	1	pop the stack and replace the top with N \| T
^	0	0	1	0	1	0	0	1	0	pop the stack and replace the top with N ^ T
nip	0	0	1	0	1	0	0	1	1	pop the next-to-top from the data stack
drop	0	0	1	0	1	0	1	0	0	drop the top value from the stack
1+	0	0	1	0	1	1	0	0	0	Add 1 to T
1-	0	0	1	0	1	1	1	0	0	Subtract 1 from T
store	0	0	1	1	0	0	0	b	b	Store N in the T'th entry in bank "`bb`", drop the top of the data stack
fetch	0	0	1	1	0	1	0	b	b	Exchange the top of the stack with the T'th value from bank "`bb`"
store+	0	0	1	1	1	0	0	b	b	Store N in the T'th entry in bank "`bb`", nip the data stack, and increment T
store-	0	0	1	1	1	0	1	b	b	Store N in the T'th entry in bank "`bb`", nip the data stack, and decrement T
fetch+	0	0	1	1	1	1	0	b	b	Push the T'th entry from bank "`bb`" into the data stack as N and increment T
fetch-	0	0	1	1	1	1	1	b	b	Push the T'th entry from bank "`bb`" into the data stack as N and decrement T
jump	0	1	0	0	x	x	x	x	x	Jump to the address "`x_xxxx_TTTT_TTTT`"
jumpc	0	1	0	1	x	x	x	x	x	Conditionally jump to the address "`x_xxxx_TTTT_TTTT`"
call	0	1	1	0	x	x	x	x	x	Call the function at address "`x_xxxx_TTTT_TTTT`"
callc	0	1	1	1	x	x	x	x	x	Conditionally call the function at address "`x_xxxx_TTTT_TTTT`"
push	1	x	x	x	x	x	x	x	x	Push the 8-bit value "`xxxx_xxxx`" onto the data stack.

Detailed Descriptions

Instruction: &

Desription: Pop the data stack and replace the top with the bitwise and of the previous top and next-to-top.

Operation:

PC ← PC+1
R and return unchanged
T ← T & N
N ← stack--

Instruction: +

Desription: Pop the data stack and replace the top with the 8 sum of the previous top and next-to-top.

Operation:

PC ← PC+1
R and return unchanged
T ← N + T
N ← stack--

Instruction: +c

Desription: Push the carry bit from N+T onto the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← the msb of the 9-bit sum of N+T
N ← T
++stack ← N

Instruction: -

Desription: Pop the data stack and replace the top with the 8 difference of the previous top and next-to-top.

Operation:

PC ← PC+1
R and return unchanged
T ← N - T
N ← stack--

Instruction: -1<>

Desription: Set the top of the stack to all ones if the previous value was not all ones, otherwise set it to all zeros.

Operation:

PC ← PC+1
R and return unchanged
T ← 0xFF if T!=0xFF, 0x00 otherwise
N and stack unchanged

Instruction: -1=

Desription: Set the top of the stack to all ones if the previous value was all ones, otherwise set it to all zeros.

Operation:

PC ← PC+1
R and return unchanged
T ← 0xFF if T=0xFF, 0x00 otherwise
N and stack unchanged

Instruction: -c

Desription: Push the carry bit from N-T onto the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← the msb of the 9-bit difference N-T
N ← T
++stack ← N

Instruction: 0<>

Desription: Set the top of the stack to all ones if the previous value was not all zeros, otherwise set it to all zeros.

Operation:

PC ← PC+1
R and return unchanged
T ← 0xFF if T!=0x00, 0x00 otherwise
N and stack unchanged

Instruction: 0=

Desription: Set the top of the stack to all ones if the previous value was all zeros, otherwise set it to all zeros.

Operation:

PC ← PC+1
R and return unchanged
T ← 0xFF if T=0x00, 0x00 otherwise
N and stack unchanged

Instruction: 0>>

Desription: Right shift the top of the stack one bit, replacing the left-most bit with a zero.

Operation:

PC ← PC+1
R and return unchanged
T ← { 0, T[7], T[6], ..., T[1] }
N and stack unchanged

Instruction: 1+

Desription: Add 1 to T.

Operation:

PC ← PC+1
R and return unchanged
T ← T+1
N and stack unchanged

Instruction: 1-

Desription: Subtract 1 from T.

Operation:

PC ← PC+1
R and return unchanged
T ← T-1
N and stack unchanged

Instruction: 1>>

Desription: Right shift the top of the stack one bit, replacing the left-most bit with a zero.

Operation:

PC ← PC+1
R and return unchanged
T ← { 1, T[7], T[6], ..., T[1] }
N and stack unchanged

Instruction: <<0

Desription: Left shift the top of the stack one bit, replacing the right-most bit with a zero. Operation:

PC ← PC+1
R and return unchanged
T ← { T[6], T[5], ..., T[0], 0 }
N and stack unchanged

Instruction: <<1

Desription: Left shift the top of the stack one bit, replacing the right-most bit with a one.
Operation:

PC ← PC+1
R and return unchanged
T ← { T[6], T[5], ..., T[0], 1 }
N and stack unchanged

Instruction: <<msb

Desription: Left shift the top of the stack one bit, leaving the right-most bit unchanged.

Operation:

PC ← PC+1
R and return unchanged
T ← { T[6], T[5], ..., T[0], T[7] }
N and stack unchanged

Instruction: >r

Desription: Pop the data stack and push its previous value onto the return stack.

Operation:

PC ← PC+1
R ← T
++return ← R
T ← N
N ← stack--

Instruction: ^

Desription: Pop the data stack and replace the top with the bitwise exclusive or of the previous top and next-to-top.

Operation:

PC ← PC+1
R and return unchanged
T ← T ^ N
N ← stack--

Instruction: call

Desription: Call the function at the address constructed from the opcode and T. Discard T and push the PC onto the return stack.

Operation:

PC ← { O[4], ..., O[0], T[7], T[6], ..., T[0] }
R ← PC+1
++return ← R
T ← N
N ← stack--

Special:

Interrupts are disabled during the clock cycle immediately following a call instruction.

The assembler normally places a "nop" instruction immediately after the "call" instruction.

Instruction: callc

Desription: Conditionally call the function at the address constructed from the opcode and T. Discard T and conditionally push the next PC onto the return stack.

Operation:

if N != 0 then
  PC ← { O[4], ..., O[0], T[7], T[6], ..., T[0] }
  R ← PC
  ++return ← R
else
  PC ← PC+1
  R and return unchanged
endif
T ← N
N ← stack--

Special:

Interrupts are disabled during the clock cycle immediately following a callc instruction.

The assembler normally places a "drop" instruction immediately after the "callc" instruction.

Instruction: drop

Desription: Pop the data stack, discarding the value that had been on the top.

Operation:

PC ← PC+1
R and return unchanged
T ← N
N ← stack--

Instruction: dup

Desription: Push the top of the data stack onto the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← T
N ← T
++stack ← N

Instruction: fetch

Desription: Replace the top of the data stack with an 8 bit value from memory. The memory bank is specified by the two least-significant bits of the opcode. The index within the memory bank is specified by the previous value of the top of the stack.

Operation:

PC ← PC+1
R and return unchanged
T ← bb[T] where "bb" is the bank
N and stack unchanged
Special: See memory for instructions on using the fetch and vectorized fetch macros.

Instruction: fetch+

Desription: Push the T'th entry from bank "bb" onto the data stack as N and increment the top of the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← T+1
N ← bb[T] where "bb" is the bank
++stack
Special: See memory for instructions on using the fetch and vectorized fetch macros.

Instruction: fetch-

Desription: Push the T'th entry from bank "bb" onto the data stack as N and decrement the top of the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← T-1
N ← bb[T] where "bb" is the bank
++stack
Special: See memory for instructions on using the fetch and vectorized fetch macros.

Instruction: inport

Desription: Replace the top of the data stack with the 8 value from the port specified by the previous value of the top of the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← input_port[T]
N and stack unchanged

Special:

The recommended procedure to read from an inport port is to use the ".inport" macro.

Instruction: jump

Desription: Jump to the address constructed from the opcode and T. Discard T.

Operation:

PC ← { O[4], ..., O[0], T[7], T[6], ..., T[0] }
R and return unchanged
T ← N
N ← stack--

Special:

Interrupts are disabled during the clock cycle immediately following a jump instruction.

The assembler normally places a "nop" instruction immediately after the "jump" instruction.

Instruction: jumpc

Desription: Jump to the address constructed from the opcode and T if N is non-zero. Discard S and N.

Operation:

if N != 0 then
PC ← { O[4], ..., O[0], T[7], T[6], ..., T[0] }
else
PC ← PC+1
end if
R and return unchanged
T ← N
N ← stack--

Special:

Interrupts are disabled during the clock cycle immediately following a jumpc instruction.

The assembler normally places a "drop" instruction immediately after the "jump" instruction so that the conditional is dropped from the data stack.

Instruction: lsb>>

Desription: Right shift the top of the stack one bit, replacing the left-most bit with the previous value of the right-most bit.

Operation:

PC ← PC+1
R and return unchanged
T ← { T[0], T[7], T[6], ..., T[1] }
N and stack unchanged

Instruction: msb>>

Desription: Right shift the top of the stack one bit, preserving the value of the left-most bit.

Operation:

PC ← PC+1
R and return unchanged
T ← { T[7], T[7], T[6], ..., T[1] }
N and stack unchanged

Instruction: nip

Desription: Discard the next-to-top value on the data stack.

Operation:

PC ← PC+1
R and unchanged
T ← T
N ← stack--

Instruction: nop

Desription: No operation.

Operation:

PC &leftarrow PC + 1
R, return, T, N, and stack unchanged

Instruction: or

Desription: Pop the data stack and replace the top with the bitwise or of the previous top and next-to-top.

Operation:

PC ← PC+1
R and return unchanged
T ← T or N
N ← stack--

Instruction: outport

Desription: Pop the data stack and write the previous next-to-top to the port specified by the previous top.
Operation:

PC ← PC+1
R and return unchanged
T ← N
N ← stack--
outport[T] ← N

Special:

This instruction must be following by a "drop" in order to discard the value from the data stack that had been written to the data port. The recommended procedure to write to an output port is to use the ".outport" macro.

Instruction: over

Desription: Push the next-to-top of the data stack onto the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← N
N ← T
++stack ← N

Instruction: push

Description: Push the specified 8-bit value onto the 8-bit stack.

Operation:

PC ← PC+1
R and return unchanged
T ← opcode[7:0]
N ← T
++stack ← N

Instruction: r>

Desription: Pop the return stack and push its previous value onto the data stack.

Operation:

PC ← PC+1
R ← return--
T ← R
N ← T
++stack ← N

Instruction: r@

Desription: Push the top of the return stack onto the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← R
N ← T
++stack ← N

Instruction: return

Description: Popd the top of the return stack into the PC.

Operation:

PC ← R
R ← return--
T, N, and stack unchanged

Special: This instruction must be followed by a "nop" instruction.

Instruction: store

Desription: Drop the top of the data stack and store the previous next-to-top of the data stack at the memory location specified by the top of the data stack. The memory bank is specified by the two least significant bits of the opcode.

Operation:

PC ← PC+1
R and return unchanged
T ← N
N ← stack--
bb[T] ← N where "bb" is the bank

Special: See memory for instructions on using the store and vectorized store macros.

Instruction: store+

Desription: Nip the data stack and store the previous next-to-top of the data stack at the memory location specified by the top of the data stack. Increment the top of the data stack The memory bank is specified by the two least significant bits of the opcode.

Operation:

PC ← PC+1
R and return unchanged
T ← T+1
N ← stack--
bb[T] ← N where "bb" is the bank

Special: See memory for instructions on using the store and vectorized store macros.

Instruction: store-

Desription: Nip the data stack and store the previous next-to-top of the data stack at the memory location specified by the top of the data stack. Decrement the top of the data stack The memory bank is specified by the two least significant bits of the opcode.

Operation:

PC ← PC+1
R and return unchanged
T ← T-1
N ← stack--
bb[T] ← N where "bb" is the bank

Special: See memory for instructions on using the store and vectorized store macros.

Instruction: swap

Desription: Swap the top two values on the data stack.

Operation:

PC ← PC+1
R and return unchanged
T ← N
N ← T
stack unchanged