A long time ago I had an apple ][ .
I remember the command call – 151 But I can not remember what it did ?
CALL -151
Enter the machine code monitor -
http://www.skepticfiles.org/cowtext/apple/memorytx.htm
Update:
That link appears to be dead, here's a Wayback Machine alternative:
http://web.archive.org/web/20090315100335/http://www.skepticfiles.org/cowtext/apple/memorytx.htm
Here's the full article just in case Wayback goes away:
APPLE CALL, PEEK, POKE LIST CALL 144 SCAN THE INPUT BUFFER CALL 151 ENTER THE MONITOR NORM
APPLE CALL, PEEK, POKE LIST
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CALL -144 SCAN THE INPUT BUFFER
CALL -151 ENTER THE MONITOR NORMALLY
CALL -155 ENTER THE MONITOR & SOUND BELL
CALL -167 ENTER MONITOR AND RESET
CALL -198 RING BELL (SIMULATE CONTROL G)
CALL -211 PRINT "ERR" AND RING BELL
CALL -259 READ FROM TAPE
CALL -310 WRITE TO TAPE
CALL -321 DISPLAYS A, S, Y, P, & S REGISTERS
CALL -380 SET NORMAL VIDEO MODE
CALL -384 SET INVERSE VIDEO MODE
CALL -415 DISASSEMBLE 20 INSTRUCTIONS
CALL -458 VERIFY (COMPARE & LIST DIFFERENCES)
CALL -468 MEMORY MOVE AFTER POKING 60,61 OLD START - 62,63 OLD END
64,65 NEW END - 66,67 NEW STAR
CALL -484 MOVE
CALL -517 DISPLAY CHARACTER & UPDATE SCREEN LOCATION
CALL -531 DISPLAY CHARACTER, MASK CONTROL CHAR., & SAVE 7 REG. & ACCU
CALL -550 DISPLAY HEX VALUE OF A-REGISTER (ACCUMULATOR)
CALL -656 RING BELL AND WAIT FOR A CARRIAGE RETURN
CALL -657 GET LINE OF INPUT, NO PROMPT, NO L/F, & WAIT(COMMA,COLON OK
CALL -662 GET LINE OF INPUT, WITH PROMPT, NO L/F, & WAIT
CALL -665 GET LINE OF INPUT, WITH PROMPT, LINE FEED, & WAIT
THE ABOVE 3 CALLS (-657, -662, -665) REFER TO THE INPUT BUFFER FROM 512-767
CALL -715 GET CHARACTER
CALL -756 WAIT FOR KEY PRESS
CALL -856 TIME DELAY (POKE 69,XX TO SET TIME OF DELAY)
CALL -868 CLEARS CURSOR LINE FROM CURSOR TO END OF LINE
CALL -912 SCROLLS TEXT UP 1 LINE
CALL -922 LINE FEED
CALL -936 CLEAR SCREEN (HOME)
CALL -958 CLEAR SCREEN FROM CURSOR TO BOTTOM OF SCREEN
CALL -998 MOVES CURSOR UP 1 LINE
CALL -1008 MOVES CURSOR BACKWARD 1 SPACE
CALL -1024 DISPLAY CHARACTER ONLY
CALL -1036 MOVES CURSOR FORWARD 1 SPACE
CALL -1063 SEND BELL TO CURRENT OUTPUT DEVICE
CALL -1216 TEXT & GRAPHICS MODE
CALL -1233 MOVE CURSOR TO BOTTOM OF SCREEN
CALL -1321 CONTROL E
CALL -1717 MOVES CURSOR DOWN 5 LINES
CALL -1840 DISASSEMBLE 1 INSTRUCTION
CALL -1953 CHANGE COLOR BY +3
CALL -1994 CLEAR LO-RES SCREEN (TOP 40 LINES)
CALL -1998 CLEAR GRAPHIC SCREEN (LO-RES)
CALL -2007 VERTICAL LINE
CALL -2023 HORIZONTAL LINE
CALL -2458 ENTER MINI ASSEMBLER
CALL -3100 TURNS ON HIRES PAGE 1, WITHOUT CLEARING IT
CALL -3776 SAVE INTEGER
CALL -3973 LOAD INTEGER
CALL -6090 RUN INTEGER
CALL -8117 LIST INTEGER
CALL -8189 ENTER BASIC & CONTINUE
CALL -8192 ENTER BASIC AND RESET (INTEGER BASIC KILL)
CALL -16303 TEXT MODE
CALL -16304 GRAPHICS MODE
CALL -16336 TOGGLE SPEAKER
CALL 42350 CATALOGS DISK
CALL 54915 CLEANS STACK, CLEARS THE "OUT OF MEMORY" ERROR
CALL 64166 INITIATES A COLD START (BOOT OF THE DISK)
CALL 64246 BRAND NEW-YOU FIGURE IT OUT
CALL 64367 SCANS MEMORY LOC 1010 & 1011 & POKES VALUE INTO LOCATIONS
1012 THAT IS EQUAL TO (PEEK(1011)-165)
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PEEK 33 WIDTH OF TEXT WINDOW (1-40)
PEEK 34 TOP EDGE OF TEXT WINDOW (0-22)
PEEK 35 BOTTOM OF TEXT WINDOW (1-24)
PEEK 36 HORIZONTAL CURSOR POSITION (0-39)
PEEK 37 VERTICAL CURSOR POSITION (0-23)
PEEK 43 BOOT SLOT X 16 (AFTER BOOT)
PEEK 44 END POINT OF LAST HLIN, VLIN, OR PLOT
PEEK 48 LO-RES COLOR VALUE X 17
PEEK 50 TEXT OUTPUT FORMAT: 63=INVERSE 255=NORMAL
127=FLASH ( WITH PEEK 243 SET TO 64)
PEEK 51 PROMPT CHARACTER
PEEK 74,75 LOMEM ADDRESS (INT)
PEEK 76,77 HIMEM ADDRESS (INT)
PEEK 103,104 FP PROGRAM STARTING ADDRESS
PEEK 104 IF 8 IS RETURNED, THEN FP IS IN ROM
PEEK 105,106 FP VARIABLE SPACE STARTING ADDRESS
PEEK 107,108 FP ARRAY STARTING ADDRESS
PEEK 109,110 FP END OF NUMERIC STORAGE ADDRESS
PEEK 111,112 FP STRING STORAGE STARTING ADDRESS
PEEK 115,116 FP HIMEM ADDRESS
PEEK 117,118 FP LINE NUMBER BEING EXECUTED
PEEK 119,120 FP LINE WHERE PROGRAM STOPPED
PEEK 121,122 FP LINE BEING EXECUTED ADDRESS
PEEK 123,124 LINE WHERE DATA BEING READ
PEEK 125,126 DATA LOCATION ADDRESS
PEEK 127,128 INPUT OR DATA ADDRESS
PEEK 129,130 FP LAST USED VARIABLE NAME
PEEK 131,132 FP LAST USED VARIABLE ADDRESS
PEEK 175,176 FP END OF PROGRAM ADDRESS
PEEK 202,203 INT PROGRAM STARTING ADDRESS
PEEK 204,205 INT END OF VARIABLE STORAGE
PEEK 214 FP RUN FLAG (AUTO-RUN IF >127)
PEEK 216 ONERR FLAG (>127 IF ONERR IS ACTIVE)
PEEK 218,219 LINE WHERE ONERR OCCURED
PEEK 222 ONERR ERROR CODE
PEEK 224,225 X-COORDINATE OF LAST HPLOT
PEEK 226 Y-COORDINATE OF LAST HPLOT
PEEK 228 HCOLOR VALUE 0=0 85=2 128=4 213=6
42=1 127=3 170=5 255=7
PEEK 230 HI-RES PLOTING PAGE (32=PAGE 1 64=PAGE 2 96=PAGE 3)
PEEK 231 SCALE VALUE
PEEK 232,233 SHAPE TABLE STARTING ADDRESS
PEEK 234 HI-RES COLLISION COUNTER
PEEK 241 256 MINUS SPEED VALUE
PEEK 243 FLASH MASK (64=FLASH WHEN PEEK 50 SET TO 127)
PEEK 249 ROT VLAUE
PEEK 976-978 DOS RE-ENTRY VECTOR
PEEK 1010-1012 RESET VECTOR
PEEK 1013-1015 AMPERSAND (&) VECTOR
PEEK 1016-1018 CONTROL-Y VECTOR
PEEK 43140-43271 DOS COMMAND TABLE
PEEK 43378-43582 DOS ERROR MESSAGE TABLE
PEEK 43607 MAXFILES VALUE
PEEK 43616,46617 LENGTH OF LAST BLOAD
PEEK 43624 DRIVE NUMBER
PEEK 43626 SLOT NUMBER
PEEK 43634,43635 STARTING ADDRESS OF LAST BLOAD
PEEK 43697 MAXFILES DEFAULT VALUE
PEEK 43698 DOS COMMAND CHARACTER
PEEK 43702 BASIC FLAG (0=INT 64=FP ROM 128=FP RAM)
PEEK 44033 CATALOG TRACK NUMBER (17 IS STANDARD)
PEEK 44567 NUMBER OF CHARACTERS MINUS 1 IN CATALOG FILE NAMES
PEEK 44611 NUMBER OF DIGITS MINUS 1 IN SECTOR AND VOLUME NUMBERS
PEEK 45991-45998 FILE-TYPE CODE TABLE
PEEK 45999-46010 DISK VOLUME HEADING
PEEK 46017 DISK VOLUME NUMBER
PEEK 46064 NUMBER OF SECTORS (13=DOS 3.2 16=DOS 3.3)
PEEK 49152 READ KEYBOARD (IF >127 THEN KEY HAS BEEN PRESSED
PEEK 49200 TOGGLE SPEAKER (CLICK)
PEEK 49248 CASSETTE INPUT (>127=BINARY 1, 127 IF BUTTON PRESSED)
PEEK 49250 PADDLE 1 BUTTON (>127 IF BUTTON PRESSGD)
PEEK 49251 PADDLE 2 BUTTON (>127 IF BUTTON PRESSED)
PEEK 49252 READ GAME PADDLE 0 (0-255)
PEEK 49253 READ GAME PADDLE 1 (0-255)
PEEK 49254 READ GAME PADDLE 2 (0-255)
PEEK 49255 READ GAME PADDLE 3 (0-255)
PEEK 49408 READ SLOT 1
PEEK 49664 READ SLOT 2
PEEK 49920 READ SLOT 3
PEEK 50176 READ SLOT 4
PEEK 50432 READ SLOT 5
PEEK 50688 READ SLOT 6 (162=DISK CONROLLOR CARD)
PEEK 50944 READ SLOT 7
PEEK 64899 INDICATES WHICH COMPUTER YOU'RE USING
223=APPLE II OR II+, 234=FRANKLIN ACE OR ?, 255=APPLE IIE
POKE 33,33 SCRUNCH LISTING AND REMOVE SPACES IN QUOTE STATEMENTS
POKE 36,X USE AS PRINTER TAB (X=TAB - 1)
POKE 50,128 MAKES ALL OUTPUT TO THE SCREEN INVISIBLE
POKE 50,RANDOM SCRAMBLES OUTPUT TO SCREEN
POKE 51,0 DEFEATS "NOT DIRECT COMMAND", SOMETIMES DOESN'T WORK
POKE 82,128 MAKE CASETTE PROGRAM AUTO-RUN WHEN LOADED
POKE 214,255 SETS RUN FLAG IN FP & ANY KEY STROKES WILL RUN DISK PROGRA
POKE 216,0 CANCEL ONERR FLAG
POKE 1010,3 SETS THE RESET VECTOR TO INITIATE
POKE 1011,150 A COLD START (BOOT)
POKE 1010,102 MAKE
POKE 1011,213 RESET
POKE 1012,112 RUN
POKE 1014,165 SETS THE AMPERSAND (&) VECTOR
POKE 1015,214 TO LIST YOUR PROGRAM
POKE 1014,110 SETS THE AMPERSAND (&) VECTOR
POKE 1015,165 TO CATALOG A DISK
POKE 1912+SLOT,1 ON APPLE PARALLEL CARD (WITH P1-02 PROM) WILL ENABLE L/F'S
POKE 1912+SLOT,0 ON APPLE PARALLEL CARD (WITH P1-02 PROM) WILL ENABLE L/F'S
POKE 2049,1 THIS WILL CAUSE THE FIRST LINE OF PROGRAM TO LIST REPEATEDLY
POKE 40514,20 ALLOWS TEXT FILE GREETING PROGRAM
POKE 40514,52 ALLOWS BINARY FILE GREETING PROGRAM
POKE 40993,24 THIS ALLOWS
POKE 40994,234 DISK COMMANDS IN
POKE 40995,234 THE DIRECT MODE
POKE 42319,96 DISABLES THE INIT COMMAND
POKE 42768,234 CANCEL ALL
POKE 42769,234 DOS ERROR
POKE 42770,234 MESSAGES
POKE 43624,X SELECTS DISK DRIVE WITHOUT EXECUTING A COMMAND (48K SYSTEM)
POKE 43699,0 TURNS AN EXEC FILE OFF BUT LEAVES IT OPEN UNTIL A FP, CLOSE
POKE 43699,1 TURNS AN EXEC FILE BACK ON. INIT, OR MAXFILES IS ISSUE
POKE 44452,24 ALLOWS 20 FILE NAMES (2 EXTRA)
POKE 44605,23 BEFORE CATALOG PAUSE
POKE 44505,234 REVEALS DELETED FILE
POKE 44506,234 NAMES IN CATALG
POKE 44513,67 CATALOG WILL RETURN ONLY LOCKED FILES
POKE 44513,2 RETURN CATALOG TO NORMAL
POKE 44578,234 CANCEL CARRIAGE
POKE 44579,234 RETURNS AFTER CATALOG
POKE 44580,234 FILE NAMES
POKE 44596,234 CANCEL
POKE 44597,234 CATALOG-STOP
POKE 44598,234 WHEN SCREEN IS FULL
POKE 44599,234 STOP CATALOG AT EACH FILE
POKE 44600,234 NAME AND WAIT FOR A KEYPRESS
POKE 46922,96 THIS ALLOWS DISK
POKE 46923,234 INITIALATION
POKE 46924,234 WITHOUT PUTTING
POKE 44723,4 DOS ON THE DISK
POKE 49107,234 PREVENT LANGUAGE
POKE 49108,234 CARD FROM LOADING
POKE 49109,234 DURING RE-BOOT
POKE 49168,0 CLEAR KEYBOARD
POKE 49232,0 DISPLAY GRAPHICS
POKE 49233,0 DISPLAY TEXT
POKE 49234,0 DISPLAY FULL GRAPHICS
POKE 49235,0 DISPLAY TEXT/GRAPHICS
POKE 49236,0 DISPLAY GRAPHICS PAGE 1
POKE 49237,0 DISPLAY GRAPHICS PAGE 2
POKE 49238,0 DISPLAY LORES
POKE 49239,0 DISPLAY HIRES
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48K MEMORY MAP
DECIMAL HEX USAGE
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0-255 $0-$FF ZERO-PAGE SYSTEM STORAGE
256-511 $100-$1FF SYSTEM STACK
512-767 $200-$2FF KEYBOARD CHARACTER BUFFER
768-975 $300-$3CF OFTEN AVAILABLE AS FREE SPACE FOR USER PROGRAMS
976-1023 $3D0-3FF SYSTEM VECTORS
1024-2047 $400-$7FF TEXT AND LO-RES GRAPHICS PAGE 1
2048-LOMEM $800-LOMEM PROGRAM STORAGE
2048-3071 $800-$BFF TEXT AND LO-RES GRAPHICS PAGE 2 OR FREE SPACE
3072-8191 $C00-$1FFF FREE SPACE UNLESS RAM APPLESOFT IS IN USE
8192-16383 $2000-$3FFF HI-RES PAGE 1 OR FREE SPACE
16384-24575 $4000-$5FFF HI-RES PAGE 2 OR FREE SPACE
24576-38999 $6000-$95FF FREE SPACE AND STRING STORAGE
38400-49151 $9600-$BFFF DOS
49152-53247 $C000-$CFFF I/O HARDWARE (RESERVED)
53248-57343 $D000-$DFFF APPLESOFT IN LANGUAGE CARD OR ROM
57344-63487 $E000-$F7FF APPLESOFT OR INTEGER BASIC IN LANGUAGE CARD OR ROM
63488-65535 $F800-$FFFF SYSTEM MONITOR
PEEK: TO EXAMINE ANY MEMORY LOCATION L, PRINT PEEK (L), WHERE L IS A DECIMAL
NUMBER 0-65535. TO PEEK AT A TWO-BYTE NUMBER AT CONSEQUTIVE LOCATIONS L AND
L+1, PRINT PEEK (L) + PEEK (L+1) * 256
POKE: TO ASSIGN A VALUE X (0-255) TO LOCATION L; POKE L,X. TO POKE A TWO-BYT
NUMBER (NECESSARY IF X>255), POKE L,X-INT(X/256)*256, AND POKE L+1,INT(X/256).
CALL: TO EXECUTE A MACHINE LANGUAGE SUB ROUTINE AT LOCATION L, CALL L.
JUST FOR FUN TRY THIS: POKE 33,90. THEN TRY LISTING YOUR PROGRAM. OR TRY:
0,99 OR POKE 50,250 OR POKE 50,127. USE RESET TO RETURN TO NORMAL.
FOR TRUE RANDOM NUMBER GENERATION TRY THIS:X= RND(PEEK(78)+PEEK(79)*256)
TO LOCATE THE STARTING ADDRESS OF THE LAST BLOADED FILE USE: PEEK(-21902)+PEEK
(-21901)*256 (RESULT IS IN HEX)
TO DETERMINE THE LENGTH OF THE LAST BLOADED FILE USE: PEEK(-21920)+PEEK(-21919
*256 (RESULT IS IN HEX)
TO DETERMINE THE LINE NUMBER THAT CAUSED AN ERROR TO OCCUR, SET X TO: PEEK(218
+PEEK(219)*256
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