This article is from the Apple II Programming FAQ, by Jeff Hurlburt with numerous contributions by others.
Names shown are assembler "equate" names/labels. In a few cases, more than one label and function is associated with an address. A few soft switches have no established label. Not all switches are present on all Apple II models. In general, the later the model, the more features and soft switches are available. Many soft switches can be toggled via a Read or a Write. If only a Read or a Write is indicated, access the switch or indicator using the indicated method. Soft Switches and Status Indicators KEYBOARD = $C000 ;keyboard data (latched) (Read) ;Bit 7 is set to indicate a keypress ;is waiting, with the ASCII ;code in bits 6-0. CLR80STORE=$C000 ;80STORE Off- disable 80-column memory mapping (Write) SET80STORE=$C001 ;80STORE On- enable 80-column memory mapping (WR-only) CLRAUXRD = $C002 ;read from main 48K (WR-only) SETAUXRD = $C003 ;read from aux/alt 48K (WR-only) CLRAUXWR = $C004 ;write to main 48K (WR-only) SETAUXWR = $C005 ;write to aux/alt 48K (WR-only) CLRCXROM = $C006 ;use ROM on cards (WR-only) SETCXROM = $C007 ;use internal ROM (WR-only) CLRAUXZP = $C008 ;use main zero page, stack, & LC (WR-only) SETAUXZP = $C009 ;use alt zero page, stack, & LC (WR-only) CLRC3ROM = $C00A ;use internal Slot 3 ROM (WR-only) SETC3ROM = $C00B ;use external Slot 3 ROM (WR-only) CLR80VID = $C00C ;disable 80-column display mode (WR-only) SET80VID = $C00D ;enable 80-column display mode (WR-only) CLRALTCH = $C00E ;use main char set- norm LC, Flash UC (WR-only) SETALTCH = $C00F ;use alt char set- norm inverse, LC; no Flash (WR-only) STROBE = $C010 ;clear bit 7 of keyboard data ($C000) If read, it also provides an "any key down" flag in bit 7, with the keycode in the remaining bits. (These features only apply to the IIe and later machines.) Bit seven of these Read Status locations is 1 if the condition is true RDLCBNK2 = $C011 ;reading from LC bank $Dx 2 RDLCRAM = $C012 ;reading from LC RAM RDRAMRD = $C013 ;reading from aux/alt 48K RDRAMWR = $C014 ;writing to aux/alt 48K RDCXROM = $C015 ;using internal Slot ROM RDAUXZP = $C016 ;using Slot zero page, stack, & LC RDC3ROM = $C017 ;using external (Slot) C3 ROM RD80COL = $C018 ;80STORE is On- using 80-column memory mapping RDVBLBAR = $C019 ;not VBL (VBL signal low) RDTEXT = $C01A ;using text mode RDMIXED = $C01B ;using mixed mode RDPAGE2 = $C01C ;using text/graphics page2 RDHIRES = $C01D ;using Hi-res graphics mode RDALTCH = $C01E ;using alternate character set RD80VID = $C01F ;using 80-column display mode TAPEOUT = $C020 ;toggle the cassette output. SPEAKER = $C030 ;toggle speaker diaphragm STROBE = $C040 ;generate .5 uS low pulse @ Game pin 5 If read, you get one half-microsecond low pulse on the Game I/O STROBE pin; if write, you get two pulses. (IIe and ][+ only, not available on the IIgs). CLRTEXT = $C050 ;display graphics SETTEXT = $C051 ;display text CLRMIXED = $C052 ;clear mixed mode- enable full graphics SETMIXED = $C053 ;enable graphics/text mixed mode PAGE1 = $C054 ;select text/graphics page1 PAGE2 = $C055 ;select text/graphics page2 See IIe, IIc, IIgs manual for details on how these switches affect 80-col bank selection. CLRHIRES = $C056 ;select Lo-res SETHIRES = $C057 ;select Hi-res SETAN0 = $C058 ;Set annunciator-0 output to 0 CLRAN0 = $C059 ;Set annunciator-0 output to 1 SETAN1 = $C05A ;Set annunciator-1 output to 0 CLRAN1 = $C05B ;Set annunciator-1 output to 1 SETAN2 = $C05C ;Set annunciator-2 output to 0 CLRAN2 = $C05D ;Set annunciator-2 output to 1 SETAN3 = $C05E ;Set annunciator-3 output to 0 SETDHIRES= $C05E ;if IOUDIS Set, turn on double-hires CLRAN3 = $C05F ;Set annunciator-3 output to 1 CLRDHIRES= $C05F ;if IOUDIS Set, turn off double-hires Note: "0" is near 0V, "1" is near 5V. TAPEIN = $C060 ;bit 7 = data from cassette on Apple II, or PB3 ;II+, IIe. On IIgs bit 7 reflects the ;status of Game Port Pushbutton 3-- ;closed= 1. (read) OPNAPPLE = $C061 ;open apple (command) key data (read) CLSAPPLE = $C062 ;closed apple (option) key data (read) These are actually the first two game Pushbutton inputs (PB0 and PB1) which are borrowed by the Open Apple and Closed Apple keys. Bit 7 is set (=1) in these locations if the game switch or corresponding key is pressed. PB2 = $C063 ;game Pushbutton 2 (read) This input has an option to be connected to the shift key on the keyboard. (See info on the 'shift key mod'.) PADDLE0 = $C064 ;bit 7 = status of pdl-0 timer (read) PADDLE1 = $C065 ;bit 7 = status of pdl-1 timer (read) PADDLE2 = $C066 ;bit 7 = status of pdl-2 timer (read) PADDLE3 = $C067 ;bit 7 = status of pdl-3 timer (read) PDLTRIG = $C070 ;trigger paddles Read this to start paddle countdown, then time the period until $C064-$C067 bit 7 becomes set to determine the paddle position. This takes up to three milliseconds if the paddle is at its maximum extreme (reading of 255 via the standard firmware routine). SETIOUDIS= $C07E ;enable DHIRES & disable $C058-5F (W) CLRIOUDIS= $C07E ;disable DHIRES & enable $C058-5F (W) "Language Card" area Switches Bank 1 and Bank 2 here are the 4K banks at $D000-$DFFF. The remaining area from $E000-$FFFF is the same for both sets of switches. $C080 ;LC RAM bank2, Read and WR-protect RAM ROMIN = $C081 ;LC RAM bank2, Read ROM instead of RAM, ;two or more successive reads WR-enables RAM $C082 ;LC RAM bank2, Read ROM instead of RAM, ;WR-protect RAM LCBANK2 = $C083 ;LC RAM bank2, Read RAM ;two or more successive reads WR-enables RAM $C088 ;LC RAM bank1, Read and WR-protect RAM $C089 ;LC RAM bank1, Read ROM instead of RAM, ;two or more successive reads WR-enables RAM $C08A ;LC RAM bank1, Read ROM instead of RAM, ;WR-protect RAM LCBANK1 = $C08B ;LC RAM bank1, Read RAM ;two or more successive reads WR-enables RAM $C084-$C087 are echoes of $C080-$C083 $C08C-$C08F are echoes of $C088-$C08B CLRC8ROM = $CFFF ;disable Slot card C8 ROM Reading any location from $Cn00-$CnFF (where n is the Slot) will enable the $C800-$CFFF area for that card, if the card supports this feature. Reading $CFFF disables this area for all cards. Example: To enable double Hi-res graphics, the following code will accomplish this: STA SETHIRES STA SETAN3 STA CLRMIXED STA CLRTEXT JSR $C300 --email@example.com, David Empson, Rubywand ---------------------------- The following is a list of PEEKs, POKEs and Pointers in the zero page area. Most of the information comes from the Beagle Bros chart (1982). FP= "floating point"= Applesoft BASIC INT= Integer BASIC Note: Text window and related settings refer to 40-column mode Decimal | Hexadecimal | ----------------------------------------------------------------------------- 32 | $20 | Text window left-edge (0-39) 33 | $21 | Text window width (1-40) 34 | $22 | Text window top-edge (0-23) 35 | $23 | Text window bottom (1-24) 36 | $24 | Horizontal cursor-position (0-39) 37 | $25 | Vertical cursor-position (0-23) 43 | $2B | Boot slot * 16 (after boot only) 44 | $2C | Lo-res line end-point 48 | $30 | Lo-res COLOR * 17 50 | $32 | Text output format [63=INVERSE 255=NORMAL 127=FLASH] 51 | $33 | Prompt-character (NOTE: POKE 51,0:GOTO LINE # will | | sometimes prevent a false NOT DIRECT COMMAND | | obtained with GOTO alone.) 74-75 | $4A-$4B | LOMEM address (INT) 76-77 | $4C-$4D | HIMEM address (INT) 78-79 | $4E-$4F | Random-Number Field 103-104 | $67-$68 | Start of Applesoft program- normally set to $801 | | (2049 decimal) and location $800 is set to $00. | | NOTE: To load a program above hires page 1 (at | | $4001), POKE 103,1: POKE 104,64: POKE 16384,0 | | and LOAD the program. 105-106 | $69-$6A | LOMEM Start of varible space & end of Applesoft prgm 107-108 | $6B-$6C | Start of array space (FP) 109-110 | $6D-$6E | End of array space (FP) 111-112 | $6F-$70 | Start of string-storage (FP) 115-116 | $73-$74 | HIMEM- the highest available Applesoft address +1 117-118 | $75-$76 | Line being executed. (FP) 119-120 | $77-$78 | Line where program stopped. (FP) 121-122 | $79-$7A | Address of line executing. (FP) 123-124 | $7B-$7C | Current DATA line 125-126 | $7D-$7E | Next DATA address 127-128 | $7F-$80 | INPUT or DATA address 129-130 | $81-$82 | Var.last used. VAR$=CHR$(PEEK(129))+CHR$(PEEK(130)) 131-132 | $83-$84 | Last-Used-Varible Address (FP) 175-176 | $AF-$B0 | End of Applesoft Program (Normally=LOMEM) 202-203 | $CA-$CB | Start of Program Address (INT) 204-205 | $CC-CD | End of Varible Storage (INT) 214 | $D6 | RUN Flag (POKE 214,255 sets Applesoft run-only.) 216 | $D8 | ONERR Flag (POKE 216,0 cancels ONERR; en norm errs) 218-219 | $DA-$DB | Line# of ONERR Error 222 | $DE | Error Code (FP) 224-225 | $E0-$E1 | Horizontal Coordinate of HPLOT 226 | $E2 | Vertical Coordinate of HPLOT 232-233 | $E8-$E9 | Start address of Shape Table 241 | $F1 | 256 - SPEED value (SPEED=255 --> $F1: 01) (FP) 250-254 | $FA-$FE | Free Space (normally open to user) --Jon Relay and Apple II Textfiles ( http://www.textfiles.com/apple/ ). ---------------------------- Useful CALLs Example: from the BASIC prompt, CALL -151 enters the monitor. Hex Dec $BEF8 48888 ProDOS- recovers from "NO BUFFERS AVAILABLE" error $D683 54915 Inits Applesoft stack- scraps false "OUT OF MEMORY" error. $F328 -3288 Repairs Applesoft stack after an ONERR GOTO handles an error. $F3D4 -3116 HGR2 $F3DE -3106 HGR $F3F2 -3086 Clear HI-RES screen to Black $F3F6 -3082 Clear HI-RES screen to recent HCOLOR $F5CB -2613 Move HI-RES cursor coords to 224-226 $F800 -2048 PLOT a LO-RES POINT (AC:Y-COORD Y:X-COORD) $F819 -2023 DRAW a HORIZONTAL LO-RES LINE. $F828 -2008 DRAW a VERTICAL LO-RES LINE. $F832 -1998 CLEAR LO-RES SCREEN 1 and set GRAPHICS mode. $F836 -1994 CLEAR top 20 lines of LO-RES Graphics $F847 -1977 CALCULATE LO-RES Graphics base ADDRESS. $F85F -1953 Change LO-RES COLOR to COLOR + 3 $F940 -1728 PRINT contents of X & Y (REG 9 as 4 HEX digits) $F94C -1716 PRINT X BLANKS (X REG contains # to PRINT) $FA86 -1402 IRQ HANDLER $FA92 -1390 BREAK HANDLER $FAA6 -1370 RE-BOOTS DISK SYSTEM $FAD7 -1321 to display USER REGISTERS $FB2F -1233 TEXT- screen init $FB39 -1223 set SCREEN to TEXT mode $FB40 -1216 GR- set GRAPHICS mode $FB4B -1205 set NORMAL WINDOW $FB60 -1184 Prints the 'Apple ][' at the top of your screen. $FBC1 -1087 CALCULATE TEXT BASE ADDRESS $FBE4 -1052 SOUND BELL $FBF4 -1036 to MOVE CURSOR RIGHT $FBFD -1027 OUTPUT A-REG as ASCII on TEXT SCREEN 1 $FC10 -1008 to MOVE CURSOR LEFT $FC1A -998 to MOVE CURSOR UP $FC22 -990 PERFORM a VERTICAL TAB to ROW in ACCUMULATOR $FC2C -980 PREFORM ESCAPE FUNCTION $FC42 -958 CLEAR from CURSOR to END of PAGE (ESC -F) $FC58 -936 HOME & CLEAR SCREEN (Destroys ACCUMULATOR & Y-REG) $FC62 -926 PERFORM a CARRIAGE RETURN $FC66 -922 PERFORM a LINE FEED $FC70 -912 SCOLL UP 1 LINE (Destroys ACCUMULATOR & Y-REG) $FC95 -875 Clear entire Text line. $FC9C -868 CLEAR from CURSOR to END of LINE (ESC-E) $FDOC -756 GET KEY from KEYBOARD (Destroys A & Y-REG) WAIT for KEY PRESS. $FD5A -678 Wait for RETURN $FD5C -676 Sound Bell and wait for RETURN $FD67 -665 PREFORM CARRIAGE RETURN & GET LINE of TEXT. $FD6A -662 GET LINE of TEXT from KEYBOARD (X RETND with # of CHARACTERS) $FD6F -657 INPUT which accepts commas & colons. Here is an example: PRINT "NAME (LAST, FIRST): ";: CALL-657: N$="": FOR X= 512 TO 719: IF PEEK (X) < > 141 THEN N$= N$ + CHR$ (PEEK (X) -128) : NEXT X $FD8E -626 PRINT CARRIAGE RETURN (Destroys ACCUMULATOR & Y-REG) $FDDA -550 PRINT CONTENTS of ACCUMULATOR as 2 HEX DIGETS. $FDE3 -541 PRINT a HEX digit $FDED -531 OUTPUT CHARACTER IN ACCUMULATOR. (Destroys A & Y-REG COUNT) $FDF0 -528 GET MONITOR CHARACTER OUTPUT $FE2C -468 PERFORM MEMORY MOVE A1-A2 TO A4. Here is an example: 10 POKE 60,Source Start address Lo 20 POKE 61,Source Start address Hi 30 POKE 62,Source End address Lo 40 POKE 63,Source End address Hi 50 POKE 66,Destination address Lo 60 POKE 67,Destination address Hi 70 CALL -468 $FE80 -384 set INVERSE mode $FE84 -380 set NORMAL mode $FEBF -321 DISPLAY A,S,Y,P,S REG. (CURRENT VALUES) $FF2D -211 PRINT "ERR" & SOUNDS BELL (Destroys ACCUMULATOR & Y-REG) $FF3A -198 PRINT BELL (Destroys ACCUMULATOR & Y-REG) $FF59 -167 ENTER MONITOR RESET, TEXT mode, "COLD START" $FF65 -155 ENTER MONITOR, ring BELL, "WARM START" $FF69 -151 Go to MONITOR $FF70 -144 SCAN INPUT BUFFER (ADDRESS $200...) --The Enforcer (on Apple II Textfiles ) and Rubywand ---------------------------- You can find listings of Apple II soft switches and popular monitor routines in a manual for your computer-- e.g. the Apple II Reference Manual (for II and II+), the IIe Technical Reference Manual, the Apple IIgs Firmware Reference Manual, etc.. An excellent guide to many PEEKs & POKEs and monitor routines is the famous "Peeks, Pokes, and Pointers" poster from Beagle Bros (early 1980's). A fairly exhaustive guide to important memory locations in the Apple II is What's Where in the Apple II: An Atlas to the Apple Computer by William Luebbert (1981). Other on-line lists of PEEKs & POKEs + Monitor Routines are available at Apple II Textfiles http://www.textfiles.com/apple/ Ground's 1 World Software Wizards folder ("Mega.Peeks.and.Pokes") Ground: /Collections/1WSW/ With very few exceptions, soft switches, monitor routines, and important vectors have remained stable since early Apple II models. So, although an old chart or listing may be missing some which are available on a newer Apple II, the ones shown will almost always work. --Rubywand and Mookie