MSX2-Technical-Handbook

Figure A.5 shows the map of the MSX2 work area. In this section, the system work area and hook from F380H to FFCAH in the figure are described. The following notation is used. Length is in bytes.

Label name (address, length)

Initial value, contents, purpose

Figure A.5 Work area

FFFF    ---------------------------
        | slot selection register |
FFFC    |-------------------------|
        |         reserved        |
FFF8    |-------------------------|
FFF7    |  MAIN-ROM slot address  |
        |-------------------------|
        |  register reservation   |
        |      area for new       |
FFE7    |       VDP (9938)        |
        |-------------------------|
        |       program for       |
FFCA    |  expansion BIOS calls   |
        |-------------------------|
        |                         |
        |       hook area         |
FD9A    |                         |
        |-------------------------|
        |                         |
        |    system work area     |
F380    |                         |
        ---------------------------

Subroutines for read/write calls of the inter-slot

RDPRIM (F380H, 5)

contents: read from basic slot

WRPRIM (F385H, 7)

contents: write to basic slot

CLPRIM (F38CH, 14)

contents: basic slot call

Starting address of assembly language program of USR function, text screen

USRTAB (F39AH, 20)

initial value: FCERR
contents: starting address of assembly language program of USR function (0 to 9); the value before defining assembly language program points to FCERR (475AH).

LINL40 (F3AEH, 1)

initial value: 39
contents: screen width per line at SCREEN 0 (set by WIDTH statement at SCREEN 0)

LINL32 (F3AFH, 1)

initial value: 32
contents: screen width per line at SCREEN 1 (set by WIDTH statement at SCREEN 1)

LINLEN (F3B0H, 1)

initial value: 29
contents: current screen width per line

CRTCNT (F3B1H, 1)

initial value: 24
contents: number of lines of current screen

CLMLST (F3B2H, 1)

initial value: 14
contents: horizontal location in the case that items are divided by commas in PRINT statement

Work for initialisation

SCREEN 0

TXTNAM (F3B3H, 2)

initial value: 0000H
contents: pattern name table

TXTCOL (F3B5H, 2)

contents: unused

TXTCGP (F3B7H, 2)

initial value: 0800H
contents: pattern generator table

TXTATR (F3B9H, 2)

contents: unused

TXTPAT (F3BBH, 2)

contents: unused

SCREEN 1

T32NAM (F3BDH, 2)

initial value: 1800H
contents: pattern name table

T32COL (F3BFH, 2)

initial value: 2000H
contents: colour table

T32CGP (F3C1H, 2)

initial value: 0000H
contents: pattern generator table

T32ATR (F3C3H, 2)

initial value: 1B00H
contents: sprite attribute table

T32PAT (F3C5H, 2)

initial value: 3800H
contents: sprite generator table

SCREEN 2

GRPNAM (F3C7H, 2)

initial value: 1800H
contents: pattern name table

GRPCOL (F3C9H, 2)

initial value: 2000H
contents: colour table

GRPCGP (F3CBH, 2)

initial value: 0000H
contents: pattern generator table

GRPATR (F3CDH, 2)

initial value: 1B00H
contents: sprite attribute table

GRPPAT (F3CFH, 2)

initial value: 3800H
contents: sprite generator table

SCREEN 3

MLTNAM (F3D1H, 2)

initial value: 0800H
contents: pattern name table

MLTCOL (F3D3H, 2)

contents: unused

MLTCGP (F3D5H, 2)

initial value: 0000H
contents: pattern generator table

MLTATR (F3D7H, 2)

initial value: 1B00H
contents: sprite attribute table

MLTPAT (F3D9H, 2)

initial value: 3800H
contents: sprite generator table

Other screen settings

CLIKSW (F3DBH, 1)

initial value: 1
contents: key click switch (0 = OFF, otherwise = ON), set by <key click switch> of SCREEN statement

CSRY (F3DCH, 1)

initial value: 1
contents: Y-coordinate of cursor

CSRX (F3DDH, 1)

initial value: 1
contents: X-coordinate of cursor

CNSDFG (F3DEH, 1)

initial value: 0
contents: function key display switch (0 = display, otherwise = no display), set by KEY ON/OFF statement

Area to save VDP registers

RG0SAV (F3DFH, 1)

initial value: 0

RG1SAV (F3E0H, 1)

initial value: E0H

RG2SAV (F3E1H, 1)

initial value: 0

RG3SAV (F3E2H, 1)

initial value: 0

RG4SAV (F3E3H, 1)

initial value: 0

RG5SAV (F3E4H, 1)

initial value: 0

RG6SAV (F3E5H, 1)

initial value: 0

RG7SAV (F3E6H, 1)

initial value: 0

STATFL (F3E7H, 1)

initial value: 0
contents: stores VDP status (contents of status register 0, in MSX2)

TRGFLG (F3E8H, 1)

initial value: FFH
contents: stores trigger button status of joystick

FORCLR (F3E9H, 1)

initial value: 15
contents: foreground colour; set by colour statement

BAKCLR (F3EAH, 1)

initial value: 4
contents: background colour; set by colour statement

BDRCLR (F3EBH, 1)

initial value: 7
contents: border colour; set by colour statement

MAXUPD (F3ECH, 3)

initial value: JP 0000H (C3H, 00H, 00H)
contents: used by CIRCLE statement internally

MINUPD (F3EFH, 3)

initial value: JP 0000H (C3H, 00H, 00H)
contents: used by CIRCLE statement internally

ATRBYT (F3F2H, 1)

initial value: 15
contents: colour code in using graphics

Work area for PLAY statement

QUEUES (F3F3H, 2)

initial value: QUETAB (F959H)
contents: points to queue table at the execution of PLAY statement

FRCNEW (F3F5H)

initial value: 255
contents: used by BASIC interpreter internally

Work area for key input

SCNCNT (F3F6H, 1)

initial value: 1
contents: interval for the key scan

REPCNT (F3F7H, 1)

initial value: 50
contents: delay until the auto-repeat of the key begins

PUTPNT (F3F8H, 2)

initial value: KEYBUF (FBF0H)
contents: points to address to write in the key buffer

GETPNT (F3FAH, 2)

initial value: KEYBUF (FBF0H)
contents: points to address to read from key buffer

Parameters for Cassette

CS120 (F3FCH, 5*2)

contents:
- 1200 baud:
  - 83 (LOW01): Low width representing bit 0
  - 92 (HIGH01): High width representing bit 0
  - 38 (LOW11): Low width representing bit 1
  - 45 (HIGH11): High width representing bit 1
  - HEADLEN * 2/256: High bytes (HEDLEN = 2000) of header bits for short header
- 2400 baud
  - 37 (LOW02): Low width representing bit 0
  - 45 (HIGH02): High width representing bit 0
  - 14 (LOW12): Low width representing bit 1
  - 22 (HIGH12): High width representing bit 1
  - HEADLEN * 4/256: High bytes (HEDLEN = 2000) of header bits for short header

LOW (F406H, 2)

initial value: LOW01, HIGH01 (by default, 1200 baud)
contents: width of LOW and HIGH which represents bit 0 of current baud rate; set by <cassette baud rate> of SCREEN statement

HIGH (F408H, 2)

initial value: LOW11, HIGH11 (by default, 1200 baud)
contents: width of LOW and HIGH which represents bit 1 of current baud rate; set by <cassette baud rate> of SCREEN statement

HEADER (F40AH, 1)

initial value: HEADLEN * 2/256 (by default, 1200 baud)
contents: header bit for the short header of current baud rate (HEADLEN = 2000); set by <cassette baud rate> of SCREEN statement

ASPCT1 (F40BH, 1)

contents: 256/aspect ratio; set by SCREEN statement to use in CIRCLE statement

ASPCT2 (F40DH, 1)

contents: 256 * aspect ratio; set by SCREEN statement to use in CIRCLE statement

ENDPRG (F40FH, 5)

initial value: “:”
contents: false end of program for RESUME NEXT statement

Work used by BASIC internally

ERRFLG (F414H, 1)

contents: area to store the error number

LPTPOS (F415H, 1)

initial value: 0
contents: printer head location

PRTFLG (F416H, 1)

contents: flag whether to send to printer

NTMSXP (F417H, 1)

contents: printer (0 = printer for MSX, otherwise not)

RAWPRT (F418H, 1)

contents: non-zero when printing in raw-mode

VLZADR (F419H, 2)

contents: address of character to be replaced by VAL function

VLZDAT (F41BH, 1)

contents: character to be replaced with 0 by VAL function

CURLIN (F41CH, 2)

contents: currently executing line number of BASIC

KBUF (F41FH, 318)

contents: crunch buffer; translated into intermediate language from BUF (F55EH)

BUFMIN (F55DH, 1)

initial value: “,”
contents: used in INPUT statement

BUF (F55EH, 258)

contents: buffer to store characters typed; where direct statements are stored in ASCII code

ENDBUF (F660H, 1)

contents: prevents overflow of BUF (F55EH)

TTYPOS (F661H, 1)

contents: virtual cursor location internally retained by BASIC

DIMFLG (F662H, 1)

contents: used by BASIC internally

VALTYP (F663H, 1)

contents: used to identify the type of variable

DORES (F664H, 1)

contents: indicates whether stored word can be crunched

DONUM (F665H, 1)

contents: flag for crunch

CONTXT (F666H, 2)

contents: stores text address used by CHRGET

CONSAV (F668H, 1)

contents: stores token of constant after calling CHRGET

CONTYP (F669H, 1)

contents: type of stored constant

CONLO (F66AH, 8)

contents: value of stored constant

MEMSIZ (F672H, 2)

contents: highest address of memory used by BASIC

STKTOP (F674H, 2)

contents: address used as stack by BASIC; depending on CLEAR statement

TXTTAB (F676H, 2)

contents: starting address of BASIC text area

TEMPPT (F768H, 2)

initial value: TEMPST (F67AH)
contents: starting address of unused area of temporary descriptor

TEMPST (F67AH, 3 * NUMTMP)

contents: area for NUMTEMP

DSCTMP (F698H, 3)

contents: string descriptor which is the result of string function

FRETOP (F69BH, 2)

contents: starting address of unused area of string area

TEMP3 (F69DH, 2)

contents: used for garbage collection or by USR function

TEMP8 (F69FH, 2)

contents: for garbage collection

ENDFOR (F6A1H, 2)

contents: stores next address of FOR statement (to begin execution from the next of FOR statement at loops)

DATLIN (F6A3H, 2)

contents: line number of DATA statement read by READ statement

SUBFLG (F6A5H, 1)

contents: flag for array for USR function

FLGINP (F6A6H, 1)

contents: flag used in INPUT or READ

TEMP (F6A7H, 2)

contents: location for temporary reservation for statement code; used for variable pointer, text address, and others

PTRFLG (F6A9H, 1)

contents: 0 if there is not a line number to be converted,otherwise not

AUTFLG (F6AAH, 1)

contents: flag for AUTO command validity (non-zero = valid, otherwise invalid)

AUTLIN (F6ABH, 2)

contents: last input line number

AUTINC (F6ADH, 2)

initial value: 10
contents: increment value of line number of AUTO command

SAVTXT (F6AFH, 2)

contents: area to store address of currently executing text; mainly used for error recovery by RESUME statement

ERRLIN (F6B3H, 2)

contents: line number where an error occurred

DOT (F6B5H, 2)

contents: last line number which was displayed in screen or entered

ERRTXT (F6B7H, 2)

contents: text address which caused an error; mainly used for error recovery by RESUME statement

ONELIN (F6B9H, 2)

contents: text address to which control jumps at error; set by ON ERROR GOTO statement

ONEFLG (F6BBH, 1)

contents: flag which indicates error routine execution (non-zero = in execution, otherwise not)

TEMP2 (F6BCH, 2)

contents: for temporary storage

OLDLIN (F6BEH, 2)

contents: line number which was terminated by Ctrl+STOP, STOP instruction, END instruction, or was executed last

OLDTXT (F6C0H, 2)

contents: address to be executed next

VARTAB (F6C2H, 2)

contents: starting address of simple variable; executing NEW statement causes [contents of TXTTAB(F676H) + 2] to be set

ARYTAB (F6C4H, 2)

contents: starting address of array table

STREND (F6C6H, 2)

contents: last address of memory in use as text area or variable area

DATPTR (F6C8H, 2)

contents: text address of data read by executing READ statement

DEFTBL (F6CAH, 26)

contents: area to store type of variable for one alphabetical character; depends on type declaration such as CLEAR, DEFSTR, !, or #

Work for user function parameter

PRMSTK (F6E4H, 2)

contents: previous definition block on stack (for garbage collection)

PRMLEN (F6E6H, 2)

contents: number of bytes of objective data

PARM1 (F6E8H, PRMSIZ)

contents: objective parameter definition table; PRMSIZ is number of bytes of definition block, initial value is 100

PRMPRV (F74CH, 2)

initial value: PRMSTK
contents: pointer to previous parameter block (for garbage collection)

PRMLN2 (F74EH, 2)

contents: size of parameter block

PARM2 (F750H, 100)

contents: for parameter storage

PRMFLG (F7B4H, 1)

contents: flag to indicate whether PARM1 was searched

ARYTA2 (F7B5H, 2)

contents: end point of search

NOFUNS (F7B7H, 1)

contents: 0 if there is not an objective function

TEMP9 (F7B8H, 2)

contents: location of temporary storage for garbage collection

FUNACT (F7BAH, 2)

contents: number of objective functions

SWPTMP (F7BCH, 8)

contents: location of temporary storage of the value of the first variable of SWAP statement

TRCFLG (F7C4H, 1)

contents: trace flag (non-zero = TRACE ON, 0 = TRACE OFF)

Work for Math-Pack

FBUFFR (F7C5H, 43)

contents: used internally by Math-Pack

DECTMP (F7F0H, 2)

contents: used to transform decimal integer to floating-point number

DECTM2 (F7F2H, 2)

contents: used at division routine execution

DECCNT (F7F4H, 2)

contents: used at division routine execution

DAC (F7F6H, 16)

contents: area to set the value to be calculated

HOLD8 (F806H, 48)

contents: register storage area for decimal multiplication

HOLD2 (F836H, 8)

contents: used internally by Math-Pack

HOLD (F83EH, 8)

contents: used internally by Math-Pack

ARG (F847H, 16)

contents: area to set the value to be calculated with DAC (F7F6H)

RNDX (F857H, 8)

contents: stores last random number in double precision real number; set by RND function

Data area used by BASIC interpreter

MAXFIL (F85FH, 1)

contents: maximum file number; set by MAXFILES statement

FILTAB (F860H, 2)

contents: starting address of file data area

NULBUF (F862H, 2)

contents: points to buffer used in SAVE and LOAD by BASIC interpreter

PTRFIL (F864H, 2)

contents: address of file data of currently accessing file

RUNFLG (F866H, 2)

contents: non-zero value if program was loaded and executed; used by R option of LOAD statement

FILNAM (F866H, 11)

contents: area to store filename

FILNM2 (F871H, 11)

contents: area to store filename

NLONLY (F87CH, 1)

contents: non-zero value if program is being loaded

SAVEND (F87DH, 2)

contents: end address of assembly language program to be saved

FNKSTR (F87FH, 160)

contents: area to store function key string (16 character x 10)

CGPNT (F91FH, 3)

contents: address to store character font on ROM

NAMBAS (F922H, 2)

contents: base address of current pattern name table

CGPBAS (F924H, 2)

contents: base address of current pattern generator table

PATBAS (F926H, 2)

contents: base address of current sprite generator table

ATRBAS (F928H, 2)

contents: base address of current sprite attribute table

CLOC (F92AH, 2)

contents: used internally by graphic routine

CMASK (F92CH, 1)

contents: used internally by graphic routine

MINDEL (F92DH, 1)

contents: used internally by graphic routine

MAXDEL (F92FH, 2)

contents: used internally by graphic routine

Data area used by CIRCLE statement

ASPECT (F931H, 2)

contents: aspect ratio of the circle; set by <ratio> of CIRCLE statement

CENCNT (F933H, 2)

contents: used internally by CIRCLE statement

CLINEF (F935H, 1)

contents: flag whether a line is drawn toward the center; specified by <angle> of CIRCLE statement

CNPNTS (F936H, 2)

contents: point to be plotted

CPLOTF (F938H, 1)

contents: used internally by CIRCLE statement

CPCNT (F939H, 2)

contents: number of one eight of the circle

CPNCNT8 (F93BH, 2)

contents: used internally by CIRCLE statement

CPCSUM (F93DH, 2)

contents: used internally by CIRCLE statement

CSTCNT (F93FH, 2)

contents: used internally by CIRCLE statement

CSCLXY (F941H, 1)

contents: scale of x and y

CSAVEA (F942H, 2)

contents: reservation area of ADVGRP

CSAVEM (F944H, 1)

contents: reservation area of ADVGRP

CXOFF (F945H, 2)

contents: x offset from the center

CYOFF (F947H, 2)

contents: y offset from the center

Data area used in PAINT statement

LOHMSK (F949H, 1)

contents: used internally by PAINT statement

LOHDIR (F94AH, 1)

contents: used internally by PAINT statement

LOHADR (F94BH, 2)

contents: used internally by PAINT statement

LOHCNT (F94DH, 2)

contents: used internally by PAINT statement

SKPCNT (F94FH, 2)

contents: skip count

MIVCNT (F951H, 2)

contents: movement count

PDIREC (F953H, 1)

contents: direction of the paint

LFPROG (F954H, 1)

contents: used internally by PAINT statement

RTPROG (F955H, 1)

contents: used internally by PAINT statement

Data area used in PLAY statement

MCLTAB (F956H, 2)

contents: points to the top of the table of PLAY macro or DRAW macro

MCLFLG (F958H, 1)

contents: assignment of PLAY/DRAW

QUETAB (F959H, 24)

contents: queue table
- +0: PUT offset
- +1: GET offset
- +2: backup character
- +3: queue length
- +4: queue address
- +5: queue address

QUEBAK (F971H, 4)

contents: used in BCKQ

VOICAQ (F975H, 128)

contents: queue of voice 1 (1 = a)

VOICBQ (F9F5H, 128)

contents: queue of voice 2 (2 = b)

VOICCQ (FA75H, 128)

contents: queue of voice 3 (3 = c)

Work area added in MSX2

DPPAGE (FAF5H, 1)

contents: display page number

ACPAGE (FAF6H, 1)

contents: active page number

AVCSAV (FAF7H, 1)

contents: reserves AV control port

EXBRSA (FAF8H, 1)

contents: SUB-ROM slot address

CHRCNT (FAF9H, 1)

contents: character counter in the buffer; used in Roman-kana translation (value is 0 <=n <=2)

ROMA (FAFAH, 2)

contents: area to store character in the buffer; used in Roman-kana translation (Japan version only)

MODE (FAFCH, 1)

contents: mode switch for VRAM size

        (0000WVV0)
             ---
             |||
             |++--- 00 = 16K VRAM
             |      01 = 64K VRAM
             |      11 = 128K VRAM
             |
             +----- 1 = mask, 0 = no mask
                    Flags whether to specify VRAM address
                    ANDed with 3FFFH in SCREEN 0 to 3;
                    in SCREEN 4 to 8, never masked

NORUSE (FAFDH, 1)

contents: unused

XSAVE (FAFEH, 2)

contents: [ I OOOOOOO XXXXXXXX ]

YSAVE (FB00H, 2)

contents: [ x OOOOOOO YYYYYYYY ]

        I = 1 lightpen interrupt request
        OOOOOOO = unsigned offset
        XXXXXXX = X-coordinate
        YYYYYYY = Y-coordinate

LOGOPR (FB02H, 1)

contents: logical operation code

Data area used by RS-232C

RSTMP (FB03H, 50)

contents: work area for RS-232C or disk

TOCNT (FB03H, 1)

contents: used internally by RS-232C routine

RSFCB (FB04H, 2)

contents:
- FB04H + 0: LOW address of RS-232C
- FB04H + 1: HIGH address of RS-232C

RSIQLN (FB06H, 5)

contents: used internally by RS-232C routine

MEXBIH (FB07H, 5)

contents:
- FB07H +0: RST 30H (0F7H)
- FB07H +1: byte data
- FB07H +2: (Low)
- FB07H +3: (High)
- FB07H +4: RET (0C9H)

OLDSTT (FB0CH, 5)

contents:
- FB0CH +0: RST 30H (0F7H)
- FB0CH +1: byte data
- FB0CH +2: (Low)
- FB0CH +3: (High)
- FB0CH +4: RET (0C9H)

OLDINT (FB12H, 5)

contents:
- FB12H +0: RST 30H (0F7H)
- FB12H +1: byte data
- FB12H +2: (Low)
- FB12H +3: (High)
- FB12H +4: RET (0C9H)

DEVNUM (FB17H, 1)

contents: used internally by RS-232C routine

DATCNT (FB18H, 3)

contents:
- FB18H +0: byte data
- FB18H +1: byte pointer
- FB18H +2: byte pointer

ERRORS (FB1BH, 1)

contents: used internally by RS-232C routine

FLAGS (FB1CH, 1)

contents: used internally by RS-232C routine

ESTBLS (FB1DH, 1)

contents: used internally by RS-232C routine

COMMSK (FB1EH, 1)

contents: used internally by RS-232C routine

LSTCOM (FB1FH, 1)

contents: used internally by RS-232C routine

LSTMOD (FB20H, 1)

contents: used internally by RS-232C routine

Data area used by DOS

reserved (FB21H to FB34H)

contents: used by DOS

Data area used by PLAY statement

(the following is the same as with MSX1)

PRSCNT (FB35H, 1)

contents:
- D1 to D0: string parse
- D7 = 0: 1 pass

SAVSP (FB36H, 2)

contents: reserves stack pointer in play

VOICEN (FB38H, 1)

contents: current interpreted voice

SAVVOL (FB39H, 2)

contents: reserves volume for the pause

MCLLEN (FB3BH, 1)

contents: used internally by PLAY statement

MCLPTR (FB3CH, 1)

contents: used internally by PLAY statement

QUEUEN (FB3EH, 1)

contents: used internally by PLAY statement

MUSICF (FB3FH, 1)

contents: interrupt flag for playing music

PLYCNT (FB40H, 1)

contents: number of PLAY statements stored in the queue

Offset from voice static data area

(offset is in decimal)

METREX (+0, 2)

contents: timer count down

VCXLEN (+2, 1)

contents: MCLLEN for this voice

VCXPTR (+3, 2)

contents: MCLPTR for this voice

VCXSTP (+5, 2)

contents: reserves the top of the stack pointer

QLENGX (+7, 1)

contents: number of bytes stored in the queue

NTICSX (+8, 2)

contents: new count down

TONPRX (+10, 2)

contents: area to set tone period

AMPPRX (+12, 1)

contents: discrimination of volume and enveloppe

ENVPRX (+13, 2)

contents: area to set enveloppe period

OCTAVX (+15, 1)

contents: area to set octave

NOTELX (+16, 1)

contents: area to set tone length

TEMPOX (+17, 1)

contents: area to set tempo

VOLUMX (+18, 1)

contents: area to set volume

ENVLPX (+19, 14)

contents: area to set enveloppe wave form

MCLSTX (+33, 3)

contents: reservation area of stack

MCLSEX (+36, 1)

contents: initialisation stack

VCBSIZ (+37, 1)

contents: static buffer size

Voice static data area

VCBA (FB41H, 37)

contents: static data for voice 0

VCBB (FB66H, 37)

contents: static data for voice 1

VCBC (FB8BH, 37)

contents: static data for voice 2

Data area

ENSTOP (FBB0H, 1)

contents: flag to enable warm start by [SHIFT+Ctrl+Kana key] (0 = disable, otherwise enable)

BASROM (FBB1H, 1)

contents: indicates BASIC text location (0 = on RAM, otherwise in ROM)

LINTTB (FBB2H, 24)

contents: line terminal table; area to keep information about each line of text screen

FSTPOS (FBCAH, 2)

contents: first character location of line from INLIN (00B1H) of BIOS

CODSAV (FBCCH, 1)

contents: area to reserve the character where the cursor is stacked

FNKSW1 (FBCDH, 1)

contents: indicates which function key is displayed at KEY ON (1 = F1 to F5 is displayed, 0 = F6 to F10 is displayed)

FNKFLG (FBCEH, 10)

contents: area to allow, inhibit, or stop the execution of the line defined in ON KEY GOSUB statement, or to reserve it for each function key; set by KEY(n)ON/OFF/STOP statement (0 = KEY(n)OFF/STOP, 1= KEY(n)ON)

ONGSBF (FBD8H, 1)

contents: flag to indicate whether event waiting in TRPTBL (FC4CH) occurred

CLIKFL (FBD9H, 1)

contents: key click flag

OLDKEY (FBDAH, 11)

contents: key matrix status (old)

NEWKEY (FBE5H, 11)

contents: key matrix status (new)

KEYBUF (FBF0H, 40)

contents: key code buffer

LINWRK (FC18H, 40)

contents: temporary reservation location used by screen handler

PATWRK (FC40H, 8)

contents: temporary reservation location used by pattern converter

BOTTOM (FC48H, 2)

contents: installed RAM starting (low) address; ordinarily 8000H in MSX2

HIMEM (FC4AH, 2)

contents: highest address of available memory; set by <memory upper limit> of CLEAR statement

TRAPTBL (FC4CH, 78)

contents: trap table used to handle interrupt; one table consists of three bytes, where first byte indicates ON/OFF/STOP status and the rest indicate the text address to be jumped to
- FC4CH to FC69H (3 * 10 bytes): used in ON KEY GOSUB
- FC6AH to FC6CH (3 * 1 byte): used in ON STOP GOSUB
- FC6DH to FC6FH (3 * 1 byte): used in ON SPRITE GOSUB
- FC70H to FC7EH (3 * 5 bytes): used in ON STRIG GOSUB
- FC7FH to FC81H (3 * 1 byte): used in ON INTERVAL GOSUB
- FC82H to FC99H: for expansion

RTYCNT (FC9AH, 1)

contents: used internally by BASIC

INTFLG (FC9BH, 1)

contents: if Ctrl+STOP is pressed, setting 03H here causes a stop

PADY (FC9CH, 1)

contents: Y-coordinate of the paddle)

PADX (FC9DH, 1)

contents: X-coordinate of the paddle)

JIFFY (FC9EH, 2)

contents: used internally by PLAY statement

INTVAL (FCA0H, 2)

contents: interval period; set by ON INTERVAL GOSUB statement

INTCNT (FCA2H, 2)

contents: counter for interval

LOWLIM (FCA4H, 1)

contents: used during reading from cassette tape

WINWID (FCA5H, 1)

contents: used during reading from cassette tape

GRPHED (FCA6H, 1)

contents: flag to send graphic character (1 = graphic character, 0 = normal character)

ESCCNT (FCA7H, 1)

contents: area to count from escape code

INSFLG (FCA8H, 1)

contents: flag to indicate insert mode (0 = normal mode, otherwise = insert mode)

CSRSW (FCA9H, 1)

contents: whether cursor is displayed (0 = no, otherwise = yes); set by <cursor swicth> of LOCATE statement

CSTYLE (FCAAH, 1)

contents: cursor shape (0 = block, otherwise = underline)

CAPST (FCABH, 1)

contents: CAPS key status (0 = CAP OFF, otherwise = CAP ON)

KANAST (FCACH, 1)

contents: kana key status (0 = kaka OFF, otherwise = kana ON)

KANAMD (FCADH, 1)

contents: kana key arrangement status (0 = 50-sound arrangement, otherwise = JIS arrangement)

FLBMEM (FCAEH, 1)

contents: 0 when loading BASIC program

SCRMOD (FCAFH, 1)

contents: current screen mode number

OLDSCR (FCB0H, 1)

contents: screen mode reservation area

CASPRV (FCB1H, 1)

contents: character reservation area used by CAS:

BRDATR (FCB2H, 1)

contents: border colour code used by PAINT; set by <border colour> in PAINT statement

GXPOS (FCB3H, 2)

contents: X-coordinate

GYPOS (FCB5H, 2)

contents: Y-coordinate

GRPACX (FCB7H, 2)

contents: graphic accumulator (X-coordinate)

GRPACY (FCB9H, 2)

contents: graphic accumulator (Y-coordinate)

DRWFLG (FCBBH, 1)

contents: flag used in DRAW statement

DRWSCL (FCBCH, 1)

contents: DRAW scaling factor (0 = no scaling, otherwise = scaling)

DRWANG (FCBDH, 1)

contents: angle at DRAW

RUNBNF (FCBEH, 1)

contents: flag to indicate BLOAD in progress, BSAVE in progress, or neither

SAVENT (FCBFH, 2)

contents: starting address of BSAVE

EXPTBL (FCC1H, 4)

contents: flag table for expansion slot; whether the slot is expanded

SLTTBL (FCC5H, 4)

contents: current slot selection status for each expansion slot register

SLTATR (FCC9H, 64)

contents: reserves attribute for each slot

SLTWRK (FD09H, 128)

contents: allocates specific work area for each slot

PROCNM (FD89H, 16)

contents: stores name of expanded statement (after CALL statement) or expansion device (after OPEN); 0 indicates the end

DEVICE (FD99H, 1)

contents: used to identify cartridge device

Hooks

H.KEYI (FD9AH)

meaning: beginning of MSXIO interrupt handling
purpose: adds the interrupt operation such as RS-232C

H.TIMI (FD9FH)

meaning: MSXIO timer interrupt handling
purpose: adds the timer interrupt handling

H.CHPH (FDA4H)

meaning: beginning of MSXIO CHPUT (one character output)
purpose: connects other console device

H.DSPC (FDA9H)

meaning: beginning of MSXIO DSPCSR (cursor display)
purpose: connects other console device

H.ERAC (FDAEH)

meaning: beginning of MSXIO ERACSR (erase cursor)
purpose: connects other console device

H.DSPF (FDB3H)

meaning: beginning of MSXIO DSPFNK (function key display)
purpose: connects other console device

H.ERAF (FDB8H)

meaning: beginning of MSXIO ERAFNK (erase function key)
purpose: connects other console device

H.TOTE (FDBDH)

meaning: beginning of MSXIO TOTEXT (set screen in text mode)
purpose: connects other console device

H.CHGE (FDC2H)

meaning: beginning of MSXIO CHGET (get one character)
purpose: connects other console device

H.INIP (FDC7H)

meaning: beginning of MSXIO INIPAT (character pattern initialisation)
purpose: uses other character set

H.KEYC (FDCCH)

meaning: beginning of MSXIO KEYCOD (key code translation)
purpose: uses other key arrangement

H.KYEA (FDD1H)

meaning: beginning of MSXIO NMI routine (Key Easy)
purpose: uses other key arrangement

H.NMI (FDD6H)

meaning: beginning of MSXIO NMI (non-maskable interrupt)
purpose: handles NMI

H.PINL (FDDBH)

meaning: beginning of MSXIO PINLIN (one line input)
purpose: uses other console input device or other input method

H.QINL (FDE0H)

meaning: beginning of MSXINL QINLIN (one line input displaying “?”)
purpose: uses other console input device or other input method

H.INLI (FDE5H)

meaning: beginning of MSXINL INLIN (one line input)
purpose: uses other console input device or other input method

H.ONGO (FDEAH)

meaning: beginning of MSXSTS INGOTP (ON GOTO)
purpose: uses other interrupt handling device

H.DSKO (FDEFH)

meaning: beginning of MSXSTS DSKO$ (disk output)
purpose: connects disk device

H.SETS (FDF4H)

meaning: beginning of MSXSTS SETS (set attribute)
purpose: connects disk device

H.NAME (FDF9H)

meaning: beginning of MSXSTS NAME (rename)
purpose: connects disk device

H.KILL (FDFEH)

meaning: beginning of MSXSTS KILL (delete file)
purpose: connects disk device

H.IPL (FE03H)

meaning: beginning of MSXSTS IPL (initial program loading)
purpose: connects disk device

H.COPY (FE08H)

meaning: beginning of MSXSTS COPY (file copy)
purpose: connects disk device

H.CMD (FE0DH)

meaning: beginning of MSXSTS CMD (expanded command)
purpose: connects disk device

H.DSKF (FE12H)

meaning: beginning of MSXSTS DSKF (unusde disk space)
purpose: connects disk device

H.DSKI (FE17H)

meaning: beginning of MSXSTS DSKI (disk input)
purpose: connects disk device

H.ATTR (FE1CH)

meaning: beginning of MSXSTS ATTR$ (attribute)
purpose: connects disk device

H.LSET (FE21H)

meaning: beginning of MSXSTS LSET (left-padded assignment)
purpose: connects disk device

H.RSET (FE26H)

meaning: beginning of MSXSTS RSET (right-padded assignment)
purpose: connects disk device

H.FIEL (FE2BH)

meaning: beginning of MSXSTS FIELD (field)
purpose: connects disk device

H.MKI$ (FE30H)

meaning: beginning of MSXSTS MKI$ (create integer)
purpose: connects disk device

H.MKS$ (FE35H)

meaning: beginning of MSXSTS MKS$ (create single precision real)
purpose: connects disk device

H.MKD$ (FE3AH)

meaning: beginning of MSXSTS MKD$ (create double precision real)
purpose: connects disk device

H.CVI (FE3FH)

meaning: beginning of MSXSTS CVI (convert integer)
purpose: connects disk device

H.CVS (FE44H)

meaning: beginning of MSXSTS CVS (convert single precision real)
purpose: connects disk device

H.CVD (FE49H)

meaning: beginning of MSXSTS CVS (convert double precision real)
purpose: connects disk device

H.GETP (FE4EH)

meaning: SPDSK GETPTR (get file pointer)
purpose: connects disk device

H.SETF (FE53H)

meaning: SPCDSK SETFIL (set file pointer)
purpose: connects disk device

H.NOFO (FE58H)

meaning: SPDSK NOFOR (OPEN statement without FOR)
purpose: connects disk device

H.NULO (FE5DH)

meaning: SPCDSK NULOPN (open unused file)
purpose: connects disk device

H.NTFL (FE62H)

meaning: SPCDSK NTFLO (file number is not 0)
purpose: connects disk device

H.MERG (FE67H)

meaning: SPCDSK MERGE (program file merge)
purpose: connects disk device

H.SAVE (FE6CH)

meaning: SPCDSK SAVE (save)
purpose: connects disk device

H.BINS (FE71H)

meaning: SPCDSK BINSAV (save in binary)
purpose: connects disk device

H.BINL (FE76H)

meaning: SPCDSK BINLOD (load in binary)
purpose: connects disk device

H.FILE (FD7BH)

meaning: SPCDSK FILES (displey filename)
purpose: connects disk device

H.DGET (FE80H)

meaning: SPCDSK DGET (disk GET)
purpose: connects disk device

H.FILO (FE85H)

meaning: SPCDSK FILOU1 (file output)
purpose: connects disk device

H.INDS (FE8AH)

meaning: SPCDSK INDSKC (disk attribute input)
purpose: connects disk device

H.RSLF (FE8FH)

meaning: SPCDSK; re-select previous drive
purpose: connects disk device

H.SAVD (FE94H)

meaning: SPCDSK; reserve current disk
purpose: connects disk device

H.LOC (FE99H)

meaning: SPCDSK LOC function (indicate location)
purpose: connects disk device

H.LOF (FE9EH)

meaning: SPCDSK LOC function (file length)
purpose: connects disk device

H.EOF (FEA3H)

meaning: SPCDSK EOF function (end of file)
purpose: connects disk device

H.FPOS (FEA8H)

meaning: SPCDSK FPOS function (file location)
purpose: connects disk device

H.BAKU (FEADH)

meaning: SPCDSK BAKUPT (backup)
purpose: connects disk device

H.PARD (FEB2H)

meaning: SPCDEV PARDEV (get peripheral name)
purpose: expands logical device name

H.NODE (FEB7H)

meaning: SPCDEV NODEVN (no device name)
purpose: sets default device name to other device

H.POSD (FEBCH)

meaning: SPCDEV POSDSK
purpose: connects disk device

H.DEVN (FEC1H)

meaning: SPCDEV DEVNAM (process device name)
purpose: expands logical device name

H.GEND (FEC6H)

meaning: SPCDEV GENDSP (FEC6H)
purpose: expands logical device name

H.RUNC (FECBH)

meaning: BIMISC RUNC (clear for RUN)

H.CLEAR (FED0H)

meaning: BIMISC CLEARC (clear for CLEAR statement)

H.LOPD (FED5H)

meaning: BIMISC LOPDFT (set loop and default value)
purpose: uses other default value for variable

H.STKE (FEDAH)

meaning: BIMISC STKERR (stack error)

H.ISFL (FEDFH)

meaning: BIMISC ISFLIO (file input-output or not)

H.OUTD (FEE4H)

meaning: BIO OUTDO (execute OUT)

H.CRDO (FEE9H)

meaning: BIO CRDO (execute CRLF)

H.DSKC (FEEEH)

meaning: BIO DSKCHI (input disk attribute)

H.DOGR (FEF3H)

meaning: GENGRP DOGRPH (execute graphic operation)

H.PRGE (FEF8H)

meaning: BINTRP PRGEND (program end)

H.ERRP (FEFDH)

meaning: BINTRP ERRPTR (error display)

H.ERRF (FF02H)

meaning: BINTRP

H.READ (FF07H)

meaning: BINTRP READY

H.MAIN (FF0CH)

meaning: BINTRP MAIN

H.DIRD (FF11H)

meaning: BINTRP DIRDO (execute direct statement)

H.FINI (FF16H)

meaning: BINTRP

H.FINE (FF1BH)

meaning: BINTRP

H.CRUN (FF20H)

meaning: BINTRP

H.CRUN (FF20H)

meaning: BINTRP

H.CRUS (FF25H)

meaning: BINTRP

H.ISRE (FF2AH)

meaning: BINTRP

H.NTFN (FF2FH)

meaning: BINTRP

H.NOTR (FF34H)

meaning: BINTRP

H.SNGF (FF39H)

meaning: BINTRP

H.NEWS (FF3EH)

meaning: BINTRP

H.GONE (FF43H)

meaning: BINTRP

H.CHRG (FF48H)

meaning: BINTRP

H.RETU (FF4DH)

meaning: BINTRP

H.PRTF (FF52H)

meaning: BINTRP

H.COMP (FF57H)

meaning: BINTRP

H.FINP (FF5CH)

meaning: BINTRP

H.TRMN (FF61H)

meaning: BINTRP

H.FRME (FF66H)

meaning: BINTRP

H.NTPL (FF6BH)

meaning: BINTRP

H.EVAL (FF70H)

meaning: BINTRP

H.OKNO (FF75H)

meaning: BINTRP

H.FING (FF7AH)

meaning: BINTRP

H.ISMI (FF7FH)

meaning: BINTRP ISMID$ (MID$ or not)

H.WIDT (FF84H)

meaning: BINTRP WIDTHS (WIDTH)

H.LIST (FF89H)

meaning: BINTRP LIST

H.BUFL (FF8EH)

meaning: BINTRP BUFLIN (buffer line)

H.FRQI (FF93H)

meaning: BINTRP FRQINT

H.SCNE (FF98H)

meaning: BINTRP

H.FRET (FF9DH)

meaning: BINTRP FRETMP

H.PTRG (FFA2H)

meaning: BIPTRG PTRGET (get pointer)
purpose: uses variable other than default value

H.PHYD (FFA7H)

meaning: MSXIO PHYDIO (physical disk input-output)
purpose: connects disk device

H.FORM (FFACH)

meaning: MSXIO FORMAT (format disk)
purpose: connects disk device

H.ERRO (FFB1H)

meaning: BINTRP ERROR
purpose: error handling for application program

H.LPTO (FFB6H)

meaning: MSXIO LPTOUT (printer output)
purpose: uses printer other than default value

H.LPTS (FFBBH)

meaning: MSXIO LPTSTT (printer status)
purpose: uses printer other than default value

H.SCRE (FFC0H)

meaning: MSXSTS SCREEN statement entry
purpose: expands SCREEN statement

Changes from the original

Address of FLAGS variable is corrected from FB1BH to FB1CH.
Address of MCLLEN variable is corrected from FB39H to FB3BH.
Address of H.FIEL hook is corrected from DE2BH to FE2BH.