Applesoft: Internals--Page Zero Memory Map

00-02STARTInitialize low RAM memory
03-05RDYJSRJumps to STROUT
06,07ADRAYIAddress of AYINT subroutine
08,09ADRGAYAddress of GIVAYF subroutine
0A-0CUSRPOKVector for USR() function
0DCHARACString delimiter
0EENDCHRString delimiter
0FCOUNTGeneral purpose counter
10DIMFLGFlag to permit arrays
11VALTYPVariable type indicator. 0=numeric, 1=string
12INTFLGVariable type indicator. 1=integer, 0=real
13GARBFLFlag to signal the need for garbage collection
14SUBFLGFlag to permit array variables.
15INPFLGDetermines if this is INPUT or READ
16TANSGNUsed for the sign during TAN() function
1A,1BSHAPEHigh-Res shape pointer
1CHCOLOR1High-Res running color mask
1DCOUNTHHigh-Res counter
26,27HBASHigh-Res base address pointer
2CH2
2DV2
45ERROV
50,51LINNUM16 bit integer work area
53,54LASTPTPointer to last used string temporary
55-5DTEMPSTTemporary string descriptor storage area
5E,5FINDEXGeneral purpose index
60,61INDEX2General purpose index
62-66RESMultiply or divide result (HO,MOH,MO,LO)
67,68TEXTABPointer to start of the program text
69,6AVARTABPointer to start of simple variable space
6B,6CARYTABPointer to start of array variable space
6D,6ESTRENDPointer to end of storage in use
6F,70FRETOPPointer to top of string free space
71,72FRESPCPointer to new string
73,74MEMSIZPointer to top of memory
75,76CURLINCurrent line number
77,78OLDLINOld line number, set up by ctrl-C, STOP, or END
79,7AOLDTXTOld text pointer
7B,7CDATLINLine number where data for next READ comes from
7D,7EDATPTRPointer to data for next READ
7F,80INPPTRPointer to where input is coming from
81,82VARNAMStorage area for a variable's name
83,84VARPNTPointer to a variable in memory
85,86FORPNTVariable pointer for FOR and LET
87,88OPPTRPointer to current formula operation in OPTAB
89OPMASKMask created by current operator
8A,8BDEFPNTPointer used in function definition
8C,8DDSCPNTPointer to a string descriptor
8ETEMPF3Temporary pointer
8FFOUR6Constant for garbage collection
90-92JMPERInternal vector
93TEMPF1Temporary pointer
94,95ARRYPTPointer into an array
94,95HIGHDSDestination of highest element in BLT.
96,97HIGHTRSource of highest element to move in BLT.
98TEMPF2
99,9ALOWDSLocation of last byte transferred into in BLT.
9B,9CLOWTRLast thing to move in BLT. See BLTU.
9D-9FDSCTMPTemporary string descriptor
9D-A2FACFloating point accumulator. (EXP,HO,MOH,MO,LO,SGN)
A3SNGFLGSign of FAC. Set up by FIN.
A4BITS
A5-AAARGFloating point argument (EXP,HO,MOH,MO,LO,SGN)
AB,ACSTRNG1Pointer to a string or descriptor
AD,AEFBUFPTPointer into FBUFFER for FOUT
AF,B0PRGENDPointer to the end of the program text
B1-C8CHRGETCharacter fetcher
C9-CDRNDXRandom number seed
D0,D1DXHigh-Res delta-X for shape and HLIN
D2DYHigh-Res delta-Y for shape and HLIN
D3QDRNTHigh-Res rotation quadrant
D4,D5EHigh-Res error for HLIN
D6RNONLYRun only flag
D8ERRFLGFlag set by ONERR GOTO
DA,DBERRLINThe line number where the error occured
DC,DDERRPOSWhere in memory did the error occur
DEERRNUMWhich error occured
DFERRSTK6502 stack pointer from REMSTK after an error
E0,E1XOHigh-Res prior X coordinate save
E2YOHigh-Res prior Y coordinate save
E4HCOLORHigh-Res color byte for HPLOT, HPOSN
E5HNDXHigh-Res horizontal offset save
E6HPAGHigh-Res page ($20 = HGR1, $40 = HGR2)
E7SCALEHigh-Res scale for SHAPE
E8,E9SHAPXHigh-Res start of shape table
EACOLLSNHigh-Res collision counter
F0FIRST
F1SPDBYTControls delay between printed characters
F2TRFLAGControls TRACE mode.
F3ORMASKControls masking for INVERSE on video output
F4-F7ERRTOPoints to the GOTO part of ONERR statement
F8REMSTK6502 Stack pointer save area.
F9ROTBYTHigh-Res rotation factor for SHAPE
100-10FFBUFFRBuffer for FOUT
200-2F0BUFInput buffer


Published Date: Feb 18, 2012