Question

A long time ago I had an apple ][ .

I remember the command call – 151 But I can not remember what it did ?

Answer 1

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  ------------------------------------------------------------------------------ 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)  ------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------                  48K MEMORY MAP     DECIMAL    HEX            USAGE ------------------------------------------------------------------------------     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  ------------------------------------------------------------------------------  E-Mail Fredric L. Rice / The Skeptic Tank