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Basic II register map

FF00-FF03 (unused)
FF04-FF05 Y.ERLOB Local base with ON ERROR
FF06-FF07 Y.BOFA Pointer: Information area of the program
FF08-FF09 Y.EOFA Pointer: Last byte of the Basic program
FF0A-FF0B Y.HEAP Pointer: First available byte in the memory
FF0C-FF0D Y.BOTM 0080 Pointer: Bottom of the memory for Basic
FF0E-FF0F Y.TOP Pointer: Top of the memory for Basic
FF10-FF11 Y.TOPPRG Pointer: Highest address for a program
FF12-FF13 Y.CONTSP Pointer: Stack that is used with CONTINUE
FF14-FF15 Y.RESSP Pointer: Stack that is used with RESUME
FF16-FF17 Y.CMDSP Pointer: Stack that is used within direct mode
FF18-FF19 Y.LOCBAS Local variablepointer
FF1A-FF1B Y.GENEND
FF1C (unused)
FF1D Y.FL Misc flags
Bit # Label Description
02 FL.SPSI Blank characters are significant
01 FL.XTND EXTEND mode
00 FL.IMODE Default INTEGER mode
FF1E Y.PREC Float precision (4 or 8 decimals)
FF1F Y.DIGITS The value of the DIGITS
FF20 Y.ASCSAV
FF21 Y.ASCPRE
FF22 Y.DEFLOW The value of the OPTION BASE
FF23 Y.INT Interrupt byte
Bit # Label Description
03 INT.STEP Single step
02 INT.DIR Direct mode
01 INT.TRC Trace mode
00 INT.CTRC Ctrl-C flag
FF24-FF25 Y.STACK
FF26 Y.PRSTAT Program status
Bit # Label Description
07 PRS.NWER New errorhandling exists
06 PRS.HRG HR-graphic exists
05 PRS.HI Program is high in memory
04 PRS.FPCO Float found in COMMON
03 PRS.FPVR Float is allocated
02 PRS.DP Double precision
00 PRS.FIX Fixed-up
FF27 Y.XQS Execution status
Bit # Label Description
03 XQS.TRC Print line number
02 XQS.RESUM RESUMEable error
01 XQS.ONERR ON ERROR routine exists
00 XQS.CONT CONTINUE is allowed
FF28-FF29 Y.CURDEF
FF2A-FF2B Y.FORCH
FF2C-FF2D Y.VARTB
FF2E-FF2F Y.VARBAS Pointer: Start of the variable list
FF30-FF31 Y.COMTOP Pointer: Top of the COMMON variables
FF32-FF33 Y.COMCS The checksum for the COMMON variables
FF34 Y.USERCS The last channel value
FF35 Y.TRCLU Logical unit with TRACE
FF36-FF37 Y.TRCVAR Latest variable
FF38-FF39 Y.VAROOT Latest VAROOT
FF3A-FF3B Y.IPSAV Instruction pointer
FF3C-FF3D Y.RDPTR Pointer: Actual position in the DATA
FF3E-FF3F Y.RDPTR1 Pointer: Actual DATA
FF40-FF41 Y.LUCH Pointer: First open file (CON:)
FF42-FF43 Y.ONERR Pointer: ON ERROR routine
FF44 Y.ERRCOD ERRCODE
FF45-FF46 Y.SPSAV Temporary storage for the SP register
FF47-FF4B Y.RND Old random number
FF4C-FF4D 0000 Pointer: Next file parameter table (IX)
FF4E LU.LU 00 Logical unit file number
FF4F LU.STAT 07 Logical unit status
FF50-FF51 LU.DCB Logical unit vector: Entrypoint
FF52-FF53 LU.POS Logical unit position (column/row)
FF54-FF55 LU.WID xx00 Logical unit row lenght (28h or 50h) / reserved
FF56 LU.FC Logical unit Last operation
FF57-FF58 LU.ISAMB Logical unit ISAM-block
FF59-FF5A LU.EOF Logical unit size block in file
FF5B-FF5C LU.BUFN Logical unit: The number of actual block in the buffer
FF5D-FF5E LU.RNDRC Logical unit: The block number for random access
FF5F LU.RNDO Logical unit: Offset of random access buffer
FF60 LU.BUFH Logical unit: Address of buffer high
FF61 LU.EXT Logical unit block extension
FF62 LU.LFT Logical unit: Numbnr of DOSBUF
FF63-FF7A UTILLU Logical unit block for temporary operations
FF7B-FF7C DEVTBA 5B11 Pointer: Device table
Offset Size Description
00h-01h 2-Byte Pointer to next device
02h-04h 3-Byte Device name
05h-06h 2-Byte Pointer to entry
07h-08h 2-Byte Internal pointer
09h Byte Internal data
FF7D-FF7E STMTBA 0609 Pointer: Instruction table
FF7F-FF80 FNKTBA DC06 Pointer: Function table
FF81-FF82 CT0BUF 00Fx Pointer: Cassette buffer 0 (high byte either FDh or FBh)
FF83-FF84 XQTPTR 2E00 Pointer: AUTOSTART-command
FF85-FF86 CTRLCPTR 23FF Pointer: Ctrl-C flag
FF87-FF89 CMDUNSA C33600 Jump: UNSAVE-routine
FF8A-FF8C NMIENT C30000 Jump: NMI-interrupt entry
FF8D-FF8F HRCLR1 C39C19 Jump: Disable HR-graphics
FF90-FF92 CONSI C34003 Jump: Read one character (GET)
FF93-FF95 KILLTYPE C39C19
FF96-FF98 USERTRAC C3BB2C Jump: Used for debugging
FF99 CASSPEED 28 Cassette speed (CAS:)
FF9A-FF9C DEBUGENT RST 08h jumps here
FF9D-FF9F RST6ENT RST 30h jumps here
FFA0-FFA2 RST7ENT RST 38h jumps here
FFA3-FFA5 ISAMOPN Available for ISAM-OPEN
FFA6-FFA8 O.MATARI Available for matrix athrimethic (evaluating)
FFA9-FFAB MAKEMAT Available for matrix handling (comparing)
FFAC-FFAD ERRPTR DOS-call to get the error text (A=errorcode)
FFAE CASBSY 00
FFAF (unused)
FFB0-FFBF DARTVEK 8703 DART vectors
FFB2-FFB3 8703
FFB4-FFB5 6D03 Vector: Interrupt address for keyboard
FFB6-FFBF 8703..
FFC0-FFCF 8703.. SIO vectors
FFD0-FFD7 CTCVEK 8703.. CTC vectors
FFD6-FFD7 8703 Vector: Interrupt address for clock
FFD8-FFDF OPTRAM Reserved for options-PROM routines
FFDC-FFDD Address to RAM-area of options-PROM
Offset Size Description
00 Byte Options PROM revision (08h or 0Ah)
02-032-byte Pointer to input buffer
04-052-byte Number of free bytes in the output buffer
06-072-byte Number of characters in the input buffer
08-092-byte Pointer to output buffer
FFE0-FFE1 TABPTR DE-save
FFE2 KEYFLG Keyboard flag
FFE3 KEYCHR Keyboard buffer
FFE4-FFE5 CASCHKAD
FFE6-FFE7 CASSUM
FFE8 CASMODE
FFE9-FFEA CASADR
FFEB-FFEC CASACTBF
FFED-FFEE CRECNR
FFEF SPT.YEAR Current year in the range from 0 through 99
FFF0 SPT.MNTH Current month in the range from 1 through 12
FFF1 SPT.DAY Current day in the range from 1 through 31 or zero to halt clock
FFF2 SPT.HOUR Current hour in the range from 0 to 23
FFF3 SPT.MIN Current minute in the range from 0 to 59
FFF4 SPT.SEC Current second in the range from 0 to 59
FFF5 SPT.TIC Current tenth of second in the range from 0 to 93
FFF6 UFD-DOS: Reset
FFF7-FFF8 UFD-DOS: Current offset
FFF9 UFD-DOS: Current drive (select code)
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This page has been created by Sami Rautiainen.
Read the small print. Last updated September 05, 2020.