\ The Rest is Silence 11OCT83HHL************************************************************* ************************************************************* *** *** *** Please direct all questions, comments, and *** *** miscellaneous personal abuse to: *** *** *** *** Henry Laxen or Michael Perry *** *** 1259 Cornell Avenue 1125 Bancroft Way *** *** Berkeley, California Berkeley, California *** *** 94706 94702 *** *** *** *** (415) 525-8582 (415) 644-3421 *** *** *** ************************************************************* ************************************************************* \ Load Screen for 8086 Dependent Code 07Apr84map ONLY FORTH ALSO DEFINITIONS DECIMAL 3 LOAD ( The Assembler ) 18 LOAD ( The Low Level for the Debugger ) 21 LOAD ( The Low Level for the MultiTasker ) 24 LOAD ( The Machine Dependent IO words ) CR .( 8086 Machine Dependent Code Loaded ) \ 8086 Assembler 11OCT83HHLONLY FORTH ALSO DEFINITIONS 1 14 +THRU CR .( 8086 Assembler Loaded ) ONLY FORTH ALSO DEFINITIONS EXIT The 8086 Assembler was written by Mike Perry. To create and assembler language definition, use the defining word CODE. It must be terminated with either END-CODE or its synonym C;. How the assembler operates is a very interesting example of the power of CREATE DOES> Basically the instructions are categorized and a defining word is created for each category. When the nmemonic for the instruction is interpreted, it compiles itself. \ 8086 Assembler 06Apr84map: LABEL CREATE ASSEMBLER ; 232 CONSTANT DOES-OP 3 CONSTANT DOES-SIZE : DOES? (S IP -- IP' F ) DUP DOES-SIZE + SWAP C@ DOES-OP = ; ASSEMBLER ALSO DEFINITIONS : C; (S -- ) END-CODE ; OCTAL DEFER C, FORTH ' C, ASSEMBLER IS C, DEFER , FORTH ' , ASSEMBLER IS , DEFER HERE FORTH ' HERE ASSEMBLER IS HERE DEFER ?>MARK DEFER ?>RESOLVE DEFER ?<MARK DEFER ?<RESOLVE \ 8086 Assembler Register Definitions 11OCT83HHL : REG 11 * SWAP 1000 * OR CONSTANT ; : REGS (S MODE N -- ) SWAP 0 DO DUP I REG LOOP DROP ; 10 0 REGS AL CL DL BL AH CH DH BH 10 1 REGS AX CX DX BX SP BP SI DI 10 2 REGS [BX+SI] [BX+DI] [BP+SI] [BP+DI] [SI] [DI] [BP] [BX] 4 2 REGS [SI+BX] [DI+BX] [SI+BP] [DI+BP] 4 3 REGS ES CS SS DS 3 4 REGS # #) S#) BP CONSTANT RP [BP] CONSTANT [RP] ( RETURN STACK POINTER ) SI CONSTANT IP [SI] CONSTANT [IP] ( INTERPRETER POINTER ) BX CONSTANT W [BX] CONSTANT [W] ( WORKING REGISTER ) \ Addressing Modes 16Oct83map: MD CREATE 1000 * , DOES> @ SWAP 7000 AND = 0<> ; 0 MD R8? 1 MD R16? 2 MD MEM? 3 MD SEG? 4 MD #? : REG? (S n -- f ) 7000 AND 2000 < 0<> ; : BIG? (S N -- F ) ABS -200 AND 0<> ; : RLOW (S n1 -- n2 ) 7 AND ; : RMID (S n1 -- n2 ) 70 AND ; VARIABLE SIZE SIZE ON : BYTE (S -- ) SIZE OFF ; : OP, (S N OP -- ) OR C, ; : W, ( OP MR -- ) R16? 1 AND OP, ; : SIZE, ( OP -- OP' ) SIZE @ 1 AND OP, ; : ,/C, (S n f -- ) IF , ELSE C, THEN ; : RR, (S MR1 MR2 -- ) RMID SWAP RLOW OR 300 OP, ; VARIABLE LOGICAL : B/L? (S n -- f ) BIG? LOGICAL @ OR ; \ Addressing 16Oct83map: MEM, (S DISP MR RMID -- ) OVER #) = IF RMID 6 OP, DROP , ELSE RMID OVER RLOW OR -ROT [BP] = OVER 0= AND IF SWAP 100 OP, C, ELSE SWAP OVER BIG? IF 200 OP, , ELSE OVER 0= IF C, DROP ELSE 100 OP, C, THEN THEN THEN THEN ; : WMEM, (S DISP MEM REG OP -- ) OVER W, MEM, ; : R/M, (S MR REG -- ) OVER REG? IF RR, ELSE MEM, THEN ; : WR/SM, (S R/M R OP -- ) 2 PICK DUP REG? IF W, RR, ELSE DROP SIZE, MEM, THEN SIZE ON ; VARIABLE INTER : FAR (S -- ) INTER ON ; : ?FAR (S n1 -- n2 ) INTER @ IF 10 OR THEN INTER OFF ; \ Defining Words to Generate Op Codes 08MAY84HHL: 1MI CREATE C, DOES> C@ C, ; : 2MI CREATE C, DOES> C@ C, 12 C, ; : 3MI CREATE C, DOES> C@ C, HERE - 1- DUP -200 177 WITHIN NOT ABORT" Branch out of Range" C, ; : 4MI CREATE C, DOES> C@ C, MEM, ; : 5MI CREATE C, DOES> C@ SIZE, SIZE ON ; : 6MI CREATE C, DOES> C@ SWAP W, ; : 7MI CREATE C, DOES> C@ 366 WR/SM, ; : 8MI CREATE C, DOES> C@ SWAP R16? 1 AND OR SWAP # = IF C, C, ELSE 10 OR C, THEN ; : 9MI CREATE C, DOES> C@ OVER R16? IF 100 OR SWAP RLOW OP, ELSE 376 WR/SM, THEN ; : 10MI CREATE C, DOES> C@ OVER CL = IF NIP 322 ELSE 320 THEN WR/SM, ; \ Defining Words to Generate Op Codes 15MAY84HHL: 11MI CREATE C, C, DOES> OVER #) = IF NIP C@ INTER @ IF 1 AND IF 352 ELSE 232 THEN C, SWAP , , INTER OFF ELSE SWAP HERE - 2- SWAP 2DUP 1 AND SWAP BIG? NOT AND IF 2 OP, C, ELSE C, 1- , THEN THEN ELSE OVER S#) = IF NIP #) SWAP THEN 377 C, 1+ C@ ?FAR R/M, THEN ; : 12MI CREATE C, C, C, DOES> OVER REG? IF C@ SWAP RLOW OP, ELSE 1+ OVER SEG? IF C@ RLOW SWAP RMID OP, ELSE COUNT SWAP C@ C, MEM, THEN THEN ; : 14MI CREATE C, DOES> C@ DUP ?FAR C, 1 AND 0= IF , THEN ; \ Defining Words to Generate Op Codes 09Apr84map: 13MI CREATE C, C, DOES> COUNT >R C@ LOGICAL ! DUP REG? IF OVER REG? IF R> OVER W, SWAP RR, ELSE OVER DUP MEM? SWAP #) = OR IF R> 2 OR WMEM, ELSE ( # ) NIP DUP RLOW 0= ( ACC? ) IF R> 4 OR OVER W, R16? ,/C, ELSE OVER B/L? OVER R16? 2DUP AND -ROT 1 AND SWAP NOT 2 AND OR 200 OP, SWAP RLOW 300 OR R> OP, ,/C, THEN THEN THEN ELSE ( MEM ) ROT DUP REG? IF R> WMEM, ELSE ( # ) DROP 2 PICK B/L? DUP NOT 2 AND 200 OR SIZE, -ROT R> MEM, SIZE @ AND ,/C, SIZE ON THEN THEN ; \ Instructions 14MAY84RKG: TEST (S source dest -- ) DUP REG? IF OVER REG? IF 204 OVER W, SWAP RR, ELSE OVER DUP MEM? SWAP #) = OR IF 204 WMEM, ELSE ( # ) NIP DUP RLOW 0= ( ACC? ) IF 250 OVER W, ELSE 366 OVER W, DUP RLOW 300 OP, THEN R16? ,/C, THEN THEN ELSE ( MEM ) ROT DUP REG? IF 204 WMEM, ELSE ( # ) DROP 366 SIZE, 0 MEM, SIZE @ ,/C, SIZE ON THEN THEN ; \ Instructions 16Oct83mapHEX : ESC (S source ext-opcode -- ) RLOW 0D8 OP, R/M, ; : INT (S N -- ) 0CD C, C, ; : SEG (S SEG -- ) RMID 26 OP, ; : XCHG (S MR1 MR2 -- ) DUP REG? IF DUP AX = IF DROP RLOW 90 OP, ELSE OVER AX = IF NIP RLOW 90 OP, ELSE 86 WR/SM, THEN THEN ELSE ROT 86 WR/SM, THEN ; : CS: CS SEG ; : DS: DS SEG ; : ES: ES SEG ; : SS: SS SEG ; \ Instructions 18APR83HHL: MOV (S S D -- ) DUP SEG? IF 8E C, R/M, ELSE DUP REG? IF OVER #) = OVER RLOW 0= AND IF A0 SWAP W, DROP , ELSE OVER SEG? IF SWAP 8C C, RR, ELSE OVER # = IF NIP DUP R16? SWAP RLOW OVER 8 AND OR B0 OP, ,/C, ELSE 8A OVER W, R/M, THEN THEN THEN ELSE ( MEM ) ROT DUP SEG? IF 8C C, MEM, ELSE DUP # = IF DROP C6 SIZE, 0 MEM, SIZE @ ,/C, ELSE OVER #) = OVER RLOW 0= AND IF A2 SWAP W, DROP , ELSE 88 OVER W, R/M, THEN THEN THEN THEN THEN SIZE ON ; \ Instructions 12Oct83map 37 1MI AAA D5 2MI AAD D4 2MI AAM 3F 1MI AAS 0 10 13MI ADC 0 00 13MI ADD 2 20 13MI AND 10 E8 11MI CALL 98 1MI CBW F8 1MI CLC FC 1MI CLD FA 1MI CLI F5 1MI CMC 0 38 13MI CMP A6 5MI CMPS 99 1MI CWD 27 1MI DAA 2F 1MI DAS 08 9MI DEC 30 7MI DIV ( ESC ) F4 1MI HLT 38 7MI IDIV 28 7MI IMUL E4 8MI IN 00 9MI INC ( INT ) 0CE 1MI INTO 0CF 1MI IRET 77 3MI JA 73 3MI JAE 72 3MI JB 76 3MI JBE E3 3MI JCXZ 74 3MI JE 7F 3MI JG 7D 3MI JGE 7C 3MI JL 7E 3MI JLE 20 E9 11MI JMP 75 3MI JNE 71 3MI JNO 79 3MI JNS 70 3MI JO 7A 3MI JPE 7B 3MI JPO 78 3MI JS 9F 1MI LAHF C5 4MI LDS 8D 4MI LEA C4 4MI LES F0 1MI LOCK 0AC 6MI LODS E2 3MI LOOP E1 3MI LOOPE E0 3MI LOOPNE \ Instructions 12Apr84map ( MOV ) 0A4 5MI MOVS 20 7MI MUL 18 7MI NEG 90 1MI NOP 10 7MI NOT 2 08 13MI OR E6 8MI OUT 8F 07 58 12MI POP 9D 1MI POPF 0FF 36 50 12MI PUSH 9C 1MI PUSHF 10 10MI RCL 18 10MI RCR F2 1MI REP F2 1MI REPNZ F3 1MI REPZ C3 14MI RET 00 10MI ROL 8 10MI ROR 9E 1MI SAHF 38 10MI SAR 0 18 13MI SBB 0AE 5MI SCAS ( SEG ) 20 10MI SHL 28 10MI SHR F9 1MI STC FD 1MI STD FB 1MI STI 0AA 6MI STOS 0 28 13MI SUB ( TEST ) 9B 1MI WAIT ( XCHG ) D7 1MI XLAT 2 30 13MI XOR C2 14MI +RET \ Structured Conditionals 09Apr84map: A?>MARK (S -- f addr ) TRUE HERE 0 C, ; : A?>RESOLVE (S f addr -- ) HERE OVER 1+ - SWAP C! ?CONDITION ; : A?<MARK (S -- f addr ) TRUE HERE ; : A?<RESOLVE (S f addr -- ) HERE 1+ - C, ?CONDITION ; ' A?>MARK ASSEMBLER IS ?>MARK ' A?>RESOLVE ASSEMBLER IS ?>RESOLVE ' A?<MARK ASSEMBLER IS ?<MARK ' A?<RESOLVE ASSEMBLER IS ?<RESOLVE HEX 75 CONSTANT 0= 74 CONSTANT 0<> 79 CONSTANT 0< 78 CONSTANT 0>= 7D CONSTANT < 7C CONSTANT >= 7F CONSTANT <= 7E CONSTANT > 73 CONSTANT U< 72 CONSTANT U>= 77 CONSTANT U<= 76 CONSTANT U> 71 CONSTANT OV DECIMAL \ Structured Conditionals 06Apr84mapHEX : IF C, ?>MARK ; : THEN ?>RESOLVE ; : ELSE 0EB IF 2SWAP THEN ; : BEGIN ?<MARK ; : UNTIL C, ?<RESOLVE ; : AGAIN 0EB UNTIL ; : WHILE IF ; : REPEAT 2SWAP AGAIN THEN ; : DO # CX MOV HERE ; : NEXT >NEXT #) JMP ; : 1PUSH >NEXT 1- #) JMP ; : 2PUSH >NEXT 2- #) JMP ; DECIMAL \ Load Screen for High Level Trace 17Oct83mapONLY FORTH ALSO DEFINITIONS 1 2 +THRU CR .( Low level Debugger Code Loaded ) ONLY FORTH ALSO DEFINITIONS EXIT The debugger is designed to let the user single step the execution of a high level definition. To invoke the debugger, type DEBUG XXX where XXX is the name of the word you wish to trace. When XXX executes, you will get a single step trace showing you the word within XXX that is about to execute, and the contents of the parameter stack. If you wish to poke around, type F and you can interpret Forth commands until you type RESUME, and execution of XXX will continue where it left off. This debugger works by patching the NEXT routine, so it is highly machine and implementation dependent. The same idea should work however on any Forth system with a centralized NEXT routine. \ High Level Trace 18APR83HHLVOCABULARY BUG BUG ALSO DEFINITIONS VARIABLE 'DEBUG ( Code field for high level trace ) VARIABLE <IP ( Lower limit of IP ) VARIABLE IP> ( Upper limit of IP ) VARIABLE CNT ( How many times thru debug next ) ASSEMBLER HEX LABEL FNEXT ( Fix the >NEXT code back to normal ) 0AD # AL MOV AL >NEXT #) MOV D88B # AX MOV AX >NEXT 1+ #) MOV RET LABEL DNEXT ( The Debugger version of a normal >NEXT ) AX LODS AX W MOV 0 [W] JMP DECIMAL \ High Level Trace 12Apr84mapHEX ASSEMBLER LABEL DEBNEXT <IP #) IP CMP U> IF IP> #) IP CMP U<= IF CNT #) AL MOV AL INC AL CNT #) MOV 2 # AL CMP 0= IF AL AL SUB AL CNT #) MOV FNEXT #) CALL IP PUSH 'DEBUG #) W MOV 0 [W] JMP THEN THEN THEN DNEXT #) JMP CODE PNEXT (S -- ) 0E9 # AL MOV AL >NEXT #) MOV DEBNEXT >NEXT 3 + - # AX MOV AX >NEXT 1+ #) MOV NEXT C; FORTH DEFINITIONS CODE UNBUG (S -- ) FNEXT #) CALL NEXT C; DECIMAL \ Load Screen for the MultiTasker 18APR83HHLONLY FORTH ALSO DEFINITIONS 1 2 +THRU CR .( MultiTasker Low Level Loaded ) ONLY FORTH ALSO DEFINITIONS EXIT The MultiTasker is loaded as an application on top of the regular Forth System. There is support for it in the nucleus in the form of USER variables and PAUSEs inserted inside of KEY EMIT and BLOCK. The Forth multitasking scheme is co-operative instead of interruptive. All IO operations cause a PAUSE to occur, and the multitasking loop looks around at all of the current task for something to do. \ Multitasking low level 08MAY84HHLCODE (PAUSE) (S -- ) IP PUSH RP PUSH UP #) BX MOV SP 0 [BX] MOV BX INC BX INC BX INC BX INC 0 [BX] BX ADD BX INC BX INC BX JMP C; CODE RESTART (S -- ) -4 # AX MOV BX POP AX BX ADD BX UP #) MOV AX POP AX POP STI 0 [BX] SP MOV CLI RP POP IP POP NEXT C; \ Manipulate Tasks 11OCT83HHLHEX 80 CONSTANT INT# : LOCAL (S base addr -- addr' ) UP @ - + ; : @LINK (S -- addr ) LINK DUP @ + 2+ ; : !LINK (S addr -- ) LINK 2+ - LINK ! ; : SLEEP (S addr -- ) E990 SWAP ENTRY LOCAL ! ; : WAKE (S addr -- ) 80CD SWAP ENTRY LOCAL ! ; : STOP (S -- ) UP @ SLEEP PAUSE ; : SINGLE (S -- ) ['] PAUSE >BODY ['] PAUSE ! ; CODE MULTI (S -- ) ' (PAUSE) @ # BX MOV BX ' PAUSE #) MOV ' RESTART @ # BX MOV DS AX MOV AX PUSH AX AX SUB AX DS MOV CS AX MOV AX INT# 4 * 2+ #) MOV BX INT# 4 * #) MOV AX POP AX DS MOV NEXT C; UP @ WAKE ENTRY !LINK DECIMAL \ Load Screen for Machine Dependent IO Words 11OCT83HHLONLY FORTH ALSO DEFINITIONS 1 1 +THRU CR .( Machine Dependent IO Words Loaded ) ONLY FORTH ALSO DEFINITIONS EXIT Since the 8086 has a seperate IO path, we define a Forth interface to it. Use P@ and P! to read or write directly to the 8086 IO ports. \ Machine Dependent IO Words 11OCT83HHLCODE PC@ (S port# -- n ) DX POP 0 AL IN AH AH SUB AX PUSH NEXT C; CODE P@ (S port# -- n ) DX POP 0 AX IN AX PUSH NEXT C; CODE PC! (S n port# -- ) DX POP AX POP 0 AL OUT NEXT C; CODE P! (S n port# -- ) DX POP AX POP 0 AX OUT NEXT C; \ Load Screen for 8086 Dependent Code 11OCT83HHL All of the Machine Dependent Code for a Particular Forth Implementation is factored out and placed into this file. For The 8086 there are 3 different components. The 8086 assembler, The run time debugger, which must have knowledge of how NEXT is implemented, and the MultiTasker, which uses code words to WAKE tasks and put them to SLEEP. \ 8086 Assembler 08OCT83HHLLABEL marks the start of a subroutine whose name returns its address. DOES-OP Is the op code of the call instruction used for DOES> U C; A synonym for END-CODE Deferring the definitions of the commas, marks, and resolves allows the same assembler to serve for both the system and the Meta-Compiler. \ 8086 Assembler Register Definitions 12Oct83map On the 8086, register names are cleverly defined constants. The value returned by registers and by modes such as #) containsboth mode and register information. The instructions use the mode information to decide how many arguments exist, and what toassemble. Like many CPUs, the 8086 uses many 3 bit fields in its opcodesThis makes octal ( base 8 ) natural for describing the registers We redefine the Registers that FORTH uses to implement its virtual machine. \ Addressing Modes 16Oct83mapMD defines words which test for various modes. R8? R16? MEM? SEG? #? test for mode equal to 0 thru 4. REG? tests for any register mode ( 8 or 16 bit). BIG? tests offsets size. True if won't fit in one byte. RLOW mask off all but low register field. RMID mask off all but middle register field. SIZE true for 16 bit, false for 8 bit. BYTE set size to 8 bit. OP, for efficiency. OR two numbers and assemble. W, assemble opcode with W field set for size of register. SIZE, assemble opcode with W field set for size of data. ,/C, assemble either 8 or 16 bits. RR, assemble register to register instruction. LOGICAL true while assembling logical instructions. B/L? see 13MI \ Addressing 16Oct83mapThese words perform most of the addressing mode encoding. MEM, handles memory reference modes. It takes a displacement, a mode/register, and a register, and encodes and assembles them. WMEM, uses MEM, after packing the register size into the opcodeR/M, assembles either a register to register or a register to or from memory mode. WR/SM, assembles either a register mode with size field, or a memory mode with size from SIZE. Default is 16 bit. Use BYTE for 8 bit size. INTER true if inter-segment jump, call, or return. FAR sets INTER true. Usage: FAR JMP, FAR CALL, FAR RET. ?FAR sets far bit, clears flag. \ Defining Words to Generate Op Codes 12Oct83map1MI define one byte constant instructions. 2MI define ascii adjust instructions. 3MI define branch instructions, with one byte offset. 4MI define LDS, LEA, LES instructions. 5MI define string instructions. 6MI define more string instructions. 7MI define multiply and divide instructions. 8MI define input and output instructions. 9MI define increment/decrement instructions. 10MI define shift/rotate instructions. *NOTE* To allow both 'ax shl' and 'ax cl shl', if the register on top of the stack is cl, shift second register by cl. If not, shift top ( only) register by one. \ Defining Words to Generate Op Codes 09Apr84map11MI define calls and jumps. notice that the first byte stored is E9 for jmp and E8 for call so C@ 1 AND is zero for call, 1 for jmp. syntax for direct intersegment: address segment #) FAR JMP 12MI define pushes and pops. 14MI defines returns. RET FAR RET n +RET n FAR +RET \ Defining Words to Generate Op Codes 16Oct83map13MI define arithmetic and logical instructions. \ Instructions 16Oct83mapTEST bits in dest \ Instructions 16Oct83map ESC INT assemble interrupt instruction. SEG assemble segment instruction. XCHG assemble register swap instruction. CS: DS: ES: SS: assemble segment over-ride instructions. \ Instructions 12Oct83mapMOV as usual, the move instruction is the most complicated. It allows more addressing modes than any other, each of which assembles something more or less unique. \ Instructions 12Oct83mapMost instructions are defined on these two screens. Mnemonics inparentheses are defined earlier or not at all. \ Instructions 12Oct83mapMost instructions are defined on these two screens. Mnemonics inparentheses are defined earlier or not at all. \ Structured Conditionals 16Oct83mapA?>MARK assembler version of forward mark. A?>RESOLVE assembler version of forward resolve. A?<MARK assembler version of backward mark. A?<RESOLVE assembler version of backward resolve. These conditional test words leave the opcodes of conditional branches to be used by the structured conditional words. For example, 5 # CX CMP 0< IF AX BX ADD ELSE AX BX SUB THEN \ Structured Conditionals 12Oct83map One of the very best features of FORTH assemblers is the abilityto use structured conditionals instead of branching to nonsense labels. \ High Level Trace 11OCT83HHL BUG The vocabulary that holds the high level trace words. FNEXT A machine language subroutine that Fixes NEXT back to the way it used to be. DNEXT A copy of next that gets exeucted instead of the normal one. \ High Level Trace 11OCT83HHLDEBNEXT is the debugger's version of next If the IP is between <IP and IP> then the contents of the execution variable 'DEBUG are executed. First the IP is pushed onto the parameter stack. The word pointed to by 'DEBUG can be any high or low level word so long as it discards the IP that was pushed before it is called, and it must terminate by callingPNEXT to patch next once again for more tracing. PNEXT patches Forth's Next to jump to DEBNEXT. This puts us into DEBUG mode and allows for tracing. FIX restores Forth's Next to its original condition. Effectively disabling tracing. \ Multitasking low level 11OCT83HHL(PAUSE) (S -- ) Puts a task to sleep by storing the IP and the RP on the parameter stack. It then saves the pointer to the parameter stack in the user area and jumps to the code pointed at by LINK, switching tasks. RESTART (S -- ) Sets the user pointer to point to a new user area and restores the parameter stack that was previously saved in the USER area. Then pops the RP and IP off of the stack and resumes execution. The inverse of PAUSE. \ Manipulate Tasks 11OCT83HHLINT# The software interrupt number to use on the 8086 LOCAL Map a User variable from the current task to another task@LINK Return a pointer the the next tasks entry point !LINK Set the link field of the current task (perhaps relative)SLEEP makes a task pause indefinitely. WAKE lets a task start again. STOP makes a task pause indefinitely. SINGLE removes the multi-tasker's scheduler/dispatcher loop. MULTI installs the multi-tasker's scheduler/dispatcher loop. By patching the appropriate INT vector and enabling PAUSE. \ Machine Dependent IO Words 07Apr84mapCODE PC@ (S port# -- n ) Fetch an 8 bit byte from an io port CODE P@ (S port# -- n ) Fetch a 16 bit word from an io port CODE PC! (S n port# -- ) Store an 8 bit byte into an io port CODE P! (S n port# -- ) Store a 16 bit word into an io port
