MSX2-Technical-Handbook

APPENDIX 1 - BIOS LISTING

This chapter lists the 126 BIOS entries available to the user.

Index

RSTs

I/O initialisation

VDP access

PSG

Keyboard, CRT, printer input-output

Game I/O access

Cassette input-output routine

Miscellaneous

Entries appended for MSX2

SUB-ROM

Changes from the original

There are two kinds of BIOS routines, the ones in MAIN-ROM and the ones in SUB-ROM. They each have different calling sequences which will be described later. The following is the entry notation.

Label name (address) *n*

Function: descriptions and notes about the function
Input: parameters used by call
Output: parameters returned by call
Registers: registers which will be used (original contentes are lost)

The value of *n has the following meanings.

*1: same as MSX1
*2: call SUB-ROM internally in screen modes 5 to 8
*3: always call SUB-ROM
*4: do not call SUB-ROM while screen modes 4 to 8 are changed

Routines without *n are appended for MSX2.

MAIN-ROM

To call routines in MAIN-ROM, the CALL or RTS instruction is used as an ordinary subroutine call.

RSTs

Among the following RSTs, RST 00H to RST 28H are used by the BASIC interpreter. RST 30H is used for inter-slot calls and RST 38H is used for hardware interrupts.

CHKRAM (0000H) *1

Function: tests RAM and sets RAM slot for the system
Input: none
Output: none
Registers: all

SYNCHR (0008H) *1

Function: tests whether the character of [HL] is the specified character. If not, it generates SYNTAX ERROR, otherwise it goes to CHRGTR (0010H).

Input: set the character to be tested in [HL] and the character to be compared next to RST instruction which calls this routine (inline parameter).

Example:        LD      HL,LETTER
              RST     08H
              DB      "A"
                       .
                       .
                       .
      LETTER: DB      "B"

Output: HL is increased by one and A receives [HL]. When the tested character is numerical, the CY flag is set; the end of the statement (00H or 3AH) causes the Z flag to be set.
Registers: AF, HL

RDSLT (000CH) *1

Function: selects the slot corresponding to the value of A and reads one byte from the memory of the slot. When this routine is called, the interrupt is inhibited and remains inhibited even after execution ends.
Input: A for the slot number (see format below), HL for the address of memory to be read ``` F000EEPP
| ||++————– Basic slot number (0 to 3) | ++—————- Expansion slot number (0 to 3) +——————— “1” when using expansion slot ```
Output: the value of memory which has been read in A
Registers: AF, BC, DE

CHRGTR (0010H) *1

Function: gets a character (or a token) from BASIC text
Input: [HL] for the character to be read
Output: HL is incremented by one and A receives [HL]. When the character is numerical, the CY flag is set; the end of the statement causes the Z flag to be set.
Registers: AF, HL

WRSLT (0014H) *1

Function: selects the slot corresponding to the value of A and writes one byte to the memory of the slot. When this routine is called, interrupts are inhibited and remain so even after execution ends.
Input: specifies a slot with A (same as RDSLT)
Output: none
Registers: AF, BC, D

OUTDO (0018H) *2

Function: sends the value to current device
Input: A for the value to be sent
- sends output to the printer when PTRFLG (F416H) is other than 0
- sends output to the file specified by PTRFIL (F864H) when PTRFIL is other than 0
Output: none
Registers: none

CALSLT (001CH) *1

Function: calls the routine in another slot (inter-slot call)
Input: specify the slot in the 8 high order buts of the IY register (same as RDSLT). IX is for the address to be called.
Output: depends on the calling routine
Registers: depends on the calling routine

DCOMPR (0020H) *1

Function: compares the contents of HL and DE
Input: HL, DE
Output: sets the Z flag for HL = DE, CY flag for HL < DE
Registers: AF

ENASLT (0024H) *1

Function: selects the slot corresponding to the value of A and enables the slot to be used. When this routine is called, interrupts are inhibited and remain so even after execution ends.
Input:
- specify the slot by A (same as RDSLT)
- specify the page to switch the slot by 2 high order bits of HL
Output: none
Registers: all

GETYPR (0028H) *1

Function: returns the type of DAC (decimal accumulator)
Input: none
Output: S, Z, P/V flags are changed depending on the type of DAC:

integer type                    single precision real type
   C = 1                                C = 1
   S = 1 *                              S = 0
   Z = 0                                Z = 0
   P/V = 1                              P/V = 0 *

string type                     double precision real type
   C = 1                                C = 0 *
   S = 0                                S = 0
   Z = 1 *                              Z = 0
   P/V = 1                              P/V = 1

Types can be recognised by the flag marked by "*".

Registers: AF

CALLF (0030H) *1

Function: calls the routine in another slot. The following is the calling sequence:

      RST     30H
      DB      n       ;n is the slot number (same as RDSLT)
      DW      nn      ;nn is the called address

Input: In the method described above
Output: depends on the calling routine
Registers: AF, and other registers depending on the calling routine

KEYINT (0038H) *1

Function: executes the timer interrupt process routine
Input: none
Output: none
Registers: none

I/O initialisation

INITIO (003BH) *1

Function: initialises the device
Input: none
Output: none
Registers: all

INIFNK (003EH) *1

Function: initialises the contents of function keys
Input: none
Output: none
Registers: all

VDP access

DISSCR (0041H) *1

Function: inhibits the screen display
Input: none
Output: none
Registers: AF, BC

ENASCR (0044H) *1

Function: displays the screen
Input: none
Output: none
Registers: all

WRTVDP (0047H) *2

Function: writes data in the VDP register
Input: C for the register number, B for data; the register number is 0 to 23 and 32 to 46
Output: none
Registers: AF, BC

RDVRM (004AH) *1

Function: reads the contents of VRAM. This is for TMS9918, so only the 14 low order bits of the VRAM address are valid. To use all bits, call NRDVRM.
Input: HL for VRAM address to be read
Output: A for the value which was read
Registers: AF

WRTVRM (004DH) *1

Function: writes data in VRAM. This is for TMS9918, so only the 14 low order bits of the VRAM address are valid. To use all bits, call NWRVRM.
Input: HL for VRAM address, A for data
Output: none
Registers: AF

SETRD (0050H) *1

Function: sets VRAM address to VDP and enables it to be read. This is used to read data from the sequential VRAM area by using the address auto-increment function of VDP. This enables faster readout than using RDVRM in a loop. This is for TMS9918, so only the 14 low order bits of VRAM address are valid. To use all bits, call NSETRD.
Input: HL for VRAM address
Output: none
Registers: AF

SETWRT (0053H) *1

Function: sets VRAM address to VDP and enables it to be written. The purpose is the same as SETRD. This is for TMS9918, so only the 14 low order bits of VRAM address are valid. To use all bits, call NSETRD.
Input: HL for VRAM address
Output: none
Registers: AF

FILVRM (0056H) *4

Function: fills the specified VRAM area with the same data. This is for TMS9918, so only the 14 low order bits of the VRAM address are valid. To use all bits, see BIGFIL.
Input: HL for VRAM address to begin writing, BC for the length of the area to be written, A for data.
Output: none
Registers: AF, BC

LDIRMV (0059H) *4

Function: block transfer from VRAM to memory
Input: HL for source address (VRAM), DE for destination address (memory), BC for the length. All bits of the VRAM address are valid.
Output: none
Registers: all

LDIRVM (005CH) *4

Function: block transfer from memory to VRAM
Input: HL for source address (memory), DE for destination address (VRAM), BC for the length. All bits of the VRAM address are valid.
Output: none
Registers: all

CHGMOD (005FH) *3

Function: changes the screen mode. The palette is not initialised. To initialise it, see CHGMDP in SUB-ROM.
Input: A for the screen mode (0 to 8)
Output: none
Registers: all

CHGCLR (0062H) *1

Function: changes the screen colour
Input:
- A for the mode
- FORCLR (F3E9H) for foreground color
- BAKCLR (F3EAH) for background color
- BDRCLR (F3EBH) for border colour
Output: none
Registers: all

NMI (0066H) *1

Function: executes NMI (Non-Maskable Interrupt) handling routine
Input: none
Output: none
Registers: none

CLRSPR (0069H) *3

Function: initialises all sprites. The sprite pattern is cleared to null, the sprite number to the sprite plane number, the sprite colour to the foregtound colour. The vertical location of the sprite is set to 209 (mode 0 to 3) or 217 (mode 4 to 8).
Input: SCRMOD (FCAFH) for the screen mode
Output: none
Registers: all

INITXT (006CH) *3

Function: initialises the screen to TEXT1 mode (40 x 24). In this routine, the palette is not initialised. To initialise the palette, call INIPLT in SUB-ROM after this call.
Input:
- TXTNAM (F3B3H) for the pattern name table
- TXTCGP (F3B7H) for the pattern generator table
- LINL40 (F3AEH) for the length of one line
Output: none
Registers: all

INIT32 (006FH) *3

Function: initialises the screen to GRAPHIC1 mode (32x24). In this routine, the palette is not initialised.
Input:
- T32NAM (F3BDH) for the pattern name table
- T32COL (F3BFH) for the colour table
- T32CGP (F3C1H) for the pattern generator table
- T32ATR (F3C3H) for the sprite attribute table
- T32PAT (F3C5H) for the sprite generator table
Output: none
Registers: all

INIGRP (0072H) *3

Function: initialises the screen to the high-resolution graphics mode. In this routine, the palette is not initialised.
Input:
- GRPNAM (F3C7H) for the pattern name table
- GRPCOL (F3C9H) for the colour table
- GRPCGP (F3CBH) for the pattern generator table
- GRPATR (F3CDH) for the sprite attribute table
- GRPPAT (F3CFH) for the sprite generator table
Output: none
Registers: all

INIMLT (0075H) *3

Function: initialises the screen to MULTI colour mode. In this routine, the palette is not initialised.
Input:
- MLTNAM (F3D1H) for the pattern name table
- MLTCOL (F3D3H) for the colour table
- MLTCGP (F3D5H) for the pattern generator table
- MLTATR (F3D7H) for the sprite attribute table
- MLTPAT (F3D9H) for the sprite generator table
Output: none
Registers: all

SETTXT (0078H) *3

Function: set only VDP in TEXT1 mode (40x24)
Input: same as INITXT
Output: none
Registers: all

SETT32 (007BH) *3

Function: set only VDP in GRAPHIC1 mode (32x24)
Input: same as INIT32
Output: none
Registers: all

SETGRP (007EH) *3

Function: set only VDP in GRAPHIC2 mode
Input: same as INIGRP
Output: none
Registers: all

SETMLT (0081H) *3

Function: set only VDP in MULTI colour mode
Input: same as INIMLT
Output: none
Registers: all

CALPAT (0084H) *1

Function: returns the address of the sprite generator table
Input: A for the sprite number
Output: HL for the address
Registers: AF, DE, HL

CALATR (0087H) *1

Function: returns the address of the sprite attribute table
Input: A for the sprite number
Output: HL for the address
Registers: AF, DE, HL

GSPSIZ (008AH) *1

Function: returns the current sprite size
Input: none
Output: A for the sprite size (in bytes). Only when the size is 16 x 16, the CY flag is set; otherwise the CY flag is reset.
Registers: AF

GRPPRT (008DH) *2

Function: displays a character on the graphic screen
Input: A for the character code. When the screen mode is 0 to 8, set the logical operation code in LOGOPR (FB02H).
Output: none
Registers: none

PSG

GICINI (0090H) *1

Function: initialises PSG and sets the initial value for the PLAY statement
Input: none
Output: none
Registers: all

WRTPSG (0093H) *1

Function: writes data in the PSG register
Input: A for PSG register number, E for data
Output: none
Registers: none

RDPSG (0096H) *1

Function: reads the PSG register value
Input: A for PSG register number
Output: A for the value which was read
Registers: none

STRTMS (0099H) *1

Function: tests whether the PLAY statement is being executed as a background task. If not, begins to execute the PLAY statement
Input: none
Output: none
Registers: all

Keyboard, CRT, printer input-output

CHSNS (009CH) *1

Function: tests the status of the keyboard buffer
Input: none
Output: the Z flag is set when the buffer is empty, otherwise the Z flag is reset
Registers: AF

CHGET (009FH) *1

Function: one character input (waiting)
Input: none
Output: A for the code of the input character
Registers: AF

CHPUT (00A2H) *1

Function: displays the character
Input: A for the character code to be displayed
Output: none
Registers: none

LPTOUT (00A5H) *1

Function: sends one character to the printer
Input: A for the character code to be sent
Output: if failed, the CY flag is set
Registers: F

LPTSTT (00A8H) *1

Function: tests the printer status
Input: none
Output:
- when A is 255 and the Z flag is reset, the printer is READY.
- when A is 0 and the Z flag is set, the printer is NOT READY.
Registers: AF

CNVCHR (00ABH) *1

Function: test for the graphic header and transforms the code
Input: A for the character code
Output:
- the CY flag is reset to not the graphic header
- the CY flag and the Z flag are set to the transformed code is set in A
- the CY flag is set and the CY flag is reset to the untransformed code is set in A
Registers: AF

PINLIN (00AEH) *1

Function: stores in the specified buffer the character codes input until the return key or STOP key is pressed.
Input: none
Output: HL for the starting address of the buffer minus 1, the CY flag is set only when it ends with the STOP key.
Registers: all

INLIN (00B1H) *1

Function: same as PINLIN except that AUTFLG (F6AAH) is set
Input: none
Output: HL for the starting address of the buffer minus 1, the CY flag is set only when it ends with the STOP key.
Registers: all

QINLIN (00B4H) *1

Function: executes INLIN with displaying “?” and one space
Input: none
Output: HL for the starting address of the buffer minus 1, the CY flag is set only when it ends with the STOP key.
Registers: all

BREAKX (00B7H) *1

Function: tests Ctrl-STOP key. In this routine, interrupts are inhibited.
Input: none
Output: the CY flag is set when pressed
Registers: AF

BEEP (00C0H) *3

Function: generates BEEP
Input: none
Output: none
Registers: all

CLS (00C3H) *3

Function: clears the screen
Input: set zero flag
Output: none
Registers: AF, BC, DE

POSIT (00C6H) *1

Function: moves the cursor
Input: H for the X-coordinate of the cursor, L for the Y-coordinate
Output: none
Registers: AF

FNKSB (00C9H) *1

Function: tests whether the function key display is active (FNKFLG). If so, displays them, otherwise erases them.
Input: FNKFLG (FBCEH)
Output: none
Registers: all

ERAFNK (00CCH) *1

Function: erases the function key display
Input: none
Output: none
Registers: all

DSPFNK (00CFH) *2

Function: displays the function keys
Input: none
Output: none
Registers: all

TOTEXT (00D2H) *1

Function: forces the screen to be in the text mode
Input: none
Output: none
Registers: all

Game I/O access

GTSTCK (00D5H) *1

Function: returns the joystick status
Input: A for the joystick number to be tested
Output: A for the joystick direction
Registers: all

GTTRIG (00D8H) *1

Function: returns the trigger button status
Input: A for the trigger button number to be tested
Output:
- When A is 0, the trigger button is not being pressed.
- When A is FFH, the trigger button is being pressed.
Registers: AF

GTPAD (00DBH) *1

Function: returns the touch pad status
Input: A for the touch pad number to be tested
Output: A for the value
Registers: all

GTPDL (00DEH) *2

Function: returns the paddle value
Input: A for the paddle number
Output: A for the value
Registers: all

Cassette input-output routine

TAPION (00E1H) *1

Function: reads the header block after turning the cassette motor ON.
Input: none
Output: if failed, the CY flag is set
Registers: all

TAPIN (00E4H) *1

Function: reads data from the tape
Input: none
Output: A for data. If failed, the CY flag is set.
Registers: all

TAPIOF (00E7H) *1

Function: stops reading the tape
Input: none
Output: none
Registers: none

TAPOON (00EAH) *1

Function: writes the header block after turning the cassette motor ON
Input: A = 0, short header; A <> 0, long header
Output: if failed, the CY flag is set
Registers: all

TAPOUT (00EDH) *1

Function: writes data on the tape
Input: A for data
Output: if failed, the CY flag is set
Registers: all

TAPOOF (00F0H) *1

Function: stops writing to the tape
Input: A for data
Output: if failed, the CY flag is set
Registers: all

STMOTR (00F3H) *1

Function: sets the cassette motor action
Input:
- A = 0 ⟶ stop
- A = 1 ⟶ start
- A = 0FFH ⟶ reverse the current action
Output: none
Registers: AF

Miscellaneous

CHGCAP (0132H) *1

Function: alternates the CAP lamp status
Input:
- A = 0 ⟶ lamp off
- A <>0 ⟶ lamp on
Output: none
Registers: AF

CHGSND (0135H) *1

Function: alternates the 1-bit sound port status
Input:
- A = 0 ⟶ OFF
- A <>0 ⟶ ON
Output: none
Registers: AF

RSLREG (0138H) *1

Function: reads the contents of current output to the basic slot register
Input: none
Output: A for the value which was read
Registers: A

WSLREG (013BH) *1

Function: writes to the primary slot register
Input: A for the value to be written
Output: none
Registers: none

RDVDP (013EH) *1

Function: reads VDP status register
Input: none
Output: A for the value which was read
Registers: A

SNSMAT (0141H) *1

Function: reads the value of the specified line from the keyboard matrix
Input: A for the specified line
Output: A for data (the bit corresponding to the pressed key will be 0)
Registers: AF, C

PHYDIO (0144H)

Function: Physical input/output for disk devices
Input:
- A for the drive number (0 = A:, 1 = B:,…)
- B for the number of sector to be read from or written to
- C for the media ID DE for the first sector number to be read rom or written to
- HL for the startinga address of the RAM buffer to be read from or written to specified sectors
- CY set for sector writing; reset for sector reading
Output:
- CY set if failed
- B for the number of sectors actually read or written
- A for the error code (only if CY set):
  - 0 = Write protected
  - 2 = Not ready
  - 4 = Data error
  - 6 = Seek error
  - 8 = Record not found
  - 10 = Write error
  - 12 = Bad parameter
  - 14 = Out of memory
  - 16 = Other error
Registers: all

ISFLIO (014AH) *1

Function: tests whether the device is active
Input: none
Output:
- A = 0 ⟶ active
- A <>0 ⟶ inactive
Registers: AF

OUTDLP (014DH) *1

Function: printer output. Different from LPTOUT in the following points:
1. TAB is expanded to spaces
2. For non-MSX printers, hiragana is transformed to katakana and graphic characters are transformed to 1-byte characters.
3. If failed, device I/O error occurs.
Input: A for data
Output: none
Registers: F

KILBUF (0156H) *1

Function: clears the keyboard buffer
Input: none
Output: none
Registers: HL

CALBAS (0159H) *1

Function: executes inter-slot call to the routine in BASIC interpreter
Input: IX for the calling address
Output: depends on the called routine
Registers: depends on the called routine

Entries appended for MSX2

SUBROM (015CH)

Function: executes inter-slot call to SUB-ROM
Input: IX for the calling address and, at the same time, pushes IX on the stack
Output: depends on the called routine
Registers: background registers and IY are reserved

EXTROM (015FH)

Function: executes inter-slot call to SUB-ROM
Input: IX for the calling address
Output: depends on the called routine
Registers: background registers and IY are reserved

EOL (0168H)

Function: deletes to the end of the line
Input: H for X-coordinate of the cursor, L for Y-coordinate
Output: none
Registers: all

BIGFIL (016BH)

Function: same function as FILVRM. Differences are as follows:
- In FILVRM, it is tested whether the screen mode is 0 to 3. If so, it treats VDP as the one which has only 16K bytes VRAM (for the compatibility with MSX1).
- In BIGFIL, the mode is not tested and actions are carried out by the given parameters.
Input: same as FILVRM
Output: same as FILVRM
Registers: same as FILVRM

NSETRD (016EH)

Function: enables VRAM to be read by setting the address
Input: HL for VRAM address
Output: none
Registers: AF

NSTWRT (0171H)

Function: enables VRAM to be written by setting the address
Input: HL for VRAM address
Output: none
Registers: AF

NRDVRM (0174H)

Function: reads the contents of VRAM
Input: HL for VRAM address to be read
Output: A for the value which was read
Registers: F

NWRVRM (0177H)

Function: writes data in VRAM
Input: HL for VRAM address, A for data
Output: none
Registers: AF

SUB-ROM

The calling sequence of SUB-ROM is as follows:

                .
                .
                .
        LD      IX, INIPLT
                         ; Set BIOS entry address
        CALL    EXTROM
                         ; Returns here
                .
                .
                .

When the contents of IX should not be destroyed, use the call as shown below.

                .
                .
                .
INIPAL: PUSH    IX
                         ; Save IX
        LD      IX, INIPLT
                         ; Set BIOS entry address
        JP      SUBROM
                         ;Returns caller of INIPAL
                .
                .
                .

GRPRT (0089H)

Function: one character output to the graphic screen (active only in screen modes 5 to 8)
Input: A for the character code
Output: none
Registers: none

NVBXLN (00C9H)

Function: draws a box
Input:
- start point: BC for X-coordinate, DE for Y-coordinate
- end point:
  - GXPOS (FCB3H) for X-coordinate
  - GYPOS (FCB5H) for Y-coordinate
- colour: ATRBYT (F3F3H) for the attribute
- logical operation code: LOGOPR (FB02H)
Output: none
Registers: all

NVBXFL (00CDH)

Function: draws a painted box
Input:
- start point: BC for X-coordinate, DE for Y-coordinate
- end point:
  - GXPOS (FCB3H) for X-coordinate
  - GYPOS (FCB5H) for Y-coordinate
- colour: ATRBYT (F3F3H) for the attribute
- logical operation code: LOGOPR (FB02H)
Output: none
Registers: all

CHGMOD (00D1H)

Function: changes the screen mode
Input: A for the screen mode (0 to 8)
Output: none
Registers: all

INITXT (00D5H)

Function: initialises the screen to TEXT1 mode (40 x 24)
Input:
- TXTNAM (F3B3H) for the pattern name table
- TXTCGP (F3B7H) for the pattern generator table
- LINL40 (F3AEH) for the length of one line
Output: none
Registers: all

INIT32 (00D9H)

Function: initialises the screen to GRAPHIC1 mode (32x24)
Input:
- T32NAM (F3BDH) for the pattern name table
- T32COL (F3BFH) for the colour table
- T32CGP (F3C1H) for the pattern generator table
- T32ATR (F3C3H) for the sprite attribute table
- T32PAT (F3C5H) for the sprite generator table
Output: none
Registers: all

INIGRP (00DDH)

Function: initialises the screen to the high-resolution graphics mode
Input:
- GRPNAM (F3C7H) for the pattern name table
- GRPCOL (F3C9H) for the colour table
- GRPCGP (F3CBH) for the pattern generator table
- GRPATR (F3CDH) for the sprite attribute table
- GRPPAT (F3CFH) for the sprite generator table
Output: none
Registers: all

INIMLT (00E1H)

Function: initialises the screen to MULTI colour mode
Input:
- MLTNAM (F3D1H) for the pattern name table
- MLTCOL (F3D3H) for the colour table
- MLTCGP (F3D5H) for the pattern generator table
- MLTATR (F3D7H) for the sprite attribute table
- MLTPAT (F3D9H) for the sprite generator table
Output: none
Registers: all

SETTXT (00E5H)

Function: sets VDP in the text mode (40x24)
Input: same as INITXT
Output: none
Registers: all

SETT32 (00E9H)

Function: ses VDP in the text mode (32x24)
Input: same as INIT32
Output: none
Registers: all

SETGRP (00EDH)

Function: sets VDP in the high-resolution mode
Input: same as INIGRP
Output: none
Registers: all

SETMLT (00F1H)

Function: sets VDP in MULTI COLOUR mode
Input: same as INIMLT
Output: none
Registers: all

CLRSPR (00F5H)

Function: initialises all sprites. The sprite pattern is set to null, sprite number to sprite plane number, and sprite colour to the foreground colour. The vertical location of the sprite is set to 217.
Input: SCRMOD (FCAFH) for the screen mode
Output: none
Registers: all

CALPAT (00F9H)

Function: returns the address of the sprite generator table (this routine is the same as CALPAT in MAIN-ROM)
Input: A for the sprite number
Output: HL for the address
Registers: AF, DE, HL

CALATR (00FDH)

Function: returns the address of the sprite attribute table (this routine is the same as CALATR in MAIN-ROM)
Input: A for the sprite number
Output: HL for the address
Registers: AF, DE, HL

GSPSIZ (0101H)

Function: returns the current sprite size (this routine is the same as GSPSIZ in MAIN-ROM)
Input: none
Output: A for the sprite size. The CY flag is set only for the size 16 x 16.
Registers: AF

GETPAT (0105H)

Function: returns the character pattern
Input: A for the character code
Output: PATWRK (FC40H) for the character pattern
Registers: all

WRTVRM (0109H)

Function: writes data in VRAM
Input: HL for VRAM address (0 TO FFFFH), A for data
Output: none
Registers: AF

RDVRM (010DH)

Function: reads the contents of VRAM
Input: HL for VRAM address (0 TO FFFFH) to be read
Output: A for the value which was read
Registers: AF

CHGCLR (0111H)

Function: changes the screen colour
Input:
- A for the mode
- FORCLR (F3E9H) for the foreground color
- BAKCLR (F3EAH) for the background color
- BDRCLR (F3EBH) for the border colour
Output: none
Registers: all

CLSSUB (0115H)

Function: clears the screen
Input: none
Output: none
Registers: all

DSPFNK (011DH)

Function: displays the function keys
Input: none
Output: none
Registers: all

WRTVDP (012DH)

Function: writes data in the VDP register
Input: C for the register number, B for data
Output: none
Registers: AF, BC

VDPSTA (0131H)

Function: reads the VDP register
Input: A for the register number (0 to 9)
Output: A for data
Registers: F

SETPAG (013DH)

Function: switches the page
Input:
- DPPAGE (FAF5H) for the display page number
- ACPAGE (FAF6H) for the active page number
Output: none
Registers: AF

INIPLT (0141H)

Function: initialises the palette (the current palette is saved in VRAM)
Input: none
Output: none
Registers: AF, BC, DE

RSTPLT (0145H)

Function: restores the palette from VRAM
Input: none
Output: none
Registers: AF, BC, DE

GETPLT (0149H)

Function: obtains the colour code from the palette
Input: A for the palette number (0 to 15)
Output:
- 4 high order bits of B for red code
- 4 low order bits of B for blue code
- 4 low order bits of C for green code
Registers: AF, DE

SETPLT (014DH)

Function: sets the colour code to the palette
Input:
- D for the palette number (0 to 15)
- 4 high order bits of A for red code
- 4 low order bits of A for blue code
- 4 low order bits of E for green code
Output: none
Registers: AF

BEEP (017DH)

Function: generates BEEP
Input: none
Output: none
Registers: all

PROMPT (0181H)

Function: displays the prompt
Input: none
Output: none
Registers: all

NEWPAD (01ADH)

Function: reads the status of mouse or light pen
Input: call with setting the following data in A; descriptions in parenthesis are return values.
- 8: light pen check (valid at 0FFH)
- 9: returns X-coordinate
- 10: returns Y-coordinate
- 11: returns the light pen switch status (0FFH, when pressed)
- 12: whether the mouse is connected to the port 1 (valid at 0FFH)
- 13: returns the offset in X direction
- 14: returns the offset in Y direction
- 15: (always 0)
- 16: whether the mouse is connected to the port 2 (valid at 0FFH)
- 17: returns the offset in X direction
- 18: returns the offset in Y direction
- 19: (always 0)
Output: A
Registers: all

CHGMDP (01B5H)

Function: changes VDP mode. The palette is initialised.
Input: A for the screen mode (0 to 8)
Output: none
Registers: all

KNJPRT (01BDH)

Function: sends a kanki to the graphic screen (modes 5 to 8)
Input: BC for JIS kanji code, A for the display mode. The display mode has the following meaning, similar to the PUT KANJI command of BASIC.
- 0: display in 16 x 16 dot
- 1: display even dots
- 2: display odd dots

REDCLK (01F5H)

Function: reads the clock data
Input: C for RAM address of the clock

  00MMAAAA
    ------
    ||++++--- Address (0 to 15)
    ++------- Mode (0 to 3)

Output: A for the data which were read (only 4 low order bits are valid)
Registers: F

WRTCLK (01F9H)

Function: writes the clock data
Input: A for the data to be written, C for RAM address of the clock
Output: none
Registers: F

Changes from the original

In description of ENASLT, the needed input in HL has been added.
In description of GETYPR, the Input field has been added.
In description of INITXT (MAIN), the reference to “INIPLOT” has been corrected to “INIPLT”.
In description of SUBROM routine, the mark “*1” has been erased.
In description of INITXT (SUB), the needed input in LINL40 has been added.
Description of PHYDIO routine has been added.