Disk-ROM BIOS
Contents |
Disk Driver table
4010H (DISKIO) (See PHYDIO in main BIOS)
| Effect: | Physical input/output for disk devices |
| Input: | F = Carry set for write, carry reset for read A = Drive number (0=A:) F8h for 360K floppy disk, 3,5 inch, sigle-side, 9 sector F9h for 720K floppy disk, 3,5 inch, double-side, 9 sector FAh for 320K floppy disk, 3,5 inch, sigle-side, 8 sector FBh for 640K floppy disk, 3,5 inch, double-side, 8 sector FCh for 180K floppy disk, 5,25 inch, sigle-side, 9 sector FDh for 360K floppy disk, 5,25 inch, double-side, 9 sector FEh for 160K floppy disk, 5,25 inch, sigle-side, 8 sector FFh for 320K floppy disk, 5,25 inch, double-side, 8 sector DE = Logical sector number (starts at 0) |
| Output: | F = Carry set on error, carry reset on success A = If error: errorcode
Error codes can be:
0 Write protected
2 Not ready
4 Data (CRC) error
6 Seek error
8 Record not found
10 Write fault
12 Other error
|
4013H (DSKCHG)
| Effect: | Check if disk has been changed. |
| Input: | A = Drive number (0=A:) B = Media descriptor |
| Output: | F = Carry set on error, carry reset on success A = If error: errorcode (see DSKIO) |
| Note: | If the disk has been changed or may have been changed (unknown) read the boot sector or the FAT sector for a disk media descriptor and |
4016H (GETDPB)
| Effect: | Get Drive Parameter Block |
| Input: | A = Drive number B = First byte of FAT (media descriptor) |
| Output: | HL+1 ... HL+18 = DPB for specified drive |
| Note: | DPB consists of
Name Offset Size Description
----------------------------------------------------------------------------
MEDIA 0 1 Media type (F8..FF)
SECSIZ 1 2 Sector size (must be 2^n)
DIRMSK 3 1 (SECSIZE/32)-1
DIRSHFT 4 1 Number of one bits in DIRMSK
CLUSMSK 5 1 (Sectors per cluster)-1
CLUSSHFT 6 1 (Number of one bits in CLUSMSK)+1
FIRFAT 7 2 Logical sector number of first FAT
FATCNT 8 1 Number of FATs
MAXENT A 1 Number of directory entries (max 254)
FIRREC B 2 Logical sector number of first data
MAXCLUS D 2 (Number of clusters (not including reserved, FAT and
directory sectors))+1
FATSIZ F 1 Number of sectors used
FIRDIR 10 2 FAT logical sector number of start of directory
|
4019H (CHOICE)
| Effect: | Get string that describes disk formatting options. |
| Input: | None |
| Output: | HL = Address of zero terminated character string (ASCIIZ) with the text with choices for a DSKFMT |
401CH (DSKFMT)
| Effect: | Format disk |
| Input: | A = Choice specified by user (1-9). See CHOICE D = Drive number (0=A:) |
| Output: | F = Carry flag reset on success, carry flag set on error
A = If error: errorcode
Error codes can be:
0 Write protected
2 Not ready
4 Data (CRC) error
6 Seek error
8 Record not found
10 Write fault
12 Bad parameter
14 Out of memory
16 Other error
|
| Notes: | Also writes a MSX boot sector at sector 0, clears all FATs (media descriptor at first byte, 0FFh at second/third byte and rest zero) |
401FH (DSKSTP)
| Effect: | Stop the drive motor of the corresponding interface. |
| Input: | None |
| Output: | None |
| Modify: | AF, BC, DE, HL, IX et IY. |
| Notes: | Not all diskinterfaces support this entry. Only valid when 401FH <> 00H |
Kernel table
4022H (BASENT)
| Effect: | BASIC cold start. Start the Basic environment and eventually run a file of Basic program from a program in machine language.
Set the variable REBOOT (0F340h) to 0 to run the AUTOEXEC.BAS file (at the root of the disk). Otherwise, there will be a return to Basic. Under MSX-DOS, when the REBOOT variable (0F340h) contains a value other than 0 it is possible to run another Basic program whose file name and length is specified in DTA (0080h). |
| Input: | None |
| Output: | None (Does not return) |
| Examples: | 1/
; Quit your DOS program and launch a BASIC program saved as NAME.BAS CALSLT equ 001Ch DTA equ 0080h BASENT equ 04022h REBOOT equ 0F340h MASTER equ 0F348h org 0100h ld a,1 ; Not 0 to ignore the AUTOEXEC.BAS if present ld (REBOOT),a ld hl,NAME ld de,DTA ld bc,END-NAME ldir ; Copy the file name ld ix,BASENT ld iy,(MASTER-1) ; Slot of the Master Disk-ROM jp CALSLT NAME: db END-NAME ; Length db "NAME.BAS",0 END: 2/ ; Quit your DOS program and go to BASIC CALSLT equ 001Ch DTA equ 0080h BASENT equ 04022h REBOOT equ 0F340h TEMPST equ 0F67Ah MASTER equ 0F348h org 0100h ld a,1 ; Not 0 to ignore the AUTOEXEC.BAS if present ld (REBOOT),a ld a,0 ld (DTA),a ; No file name ld ix,(TEMPST) ; Erases 3 bytes ld (ix),0 ; from the ld (ix+1),0 ; area reserved for ld (ix+2),0 ; the BASIC program ld ix,BASENT ld iy,(MASTER-1) ; Slot of the Master Disk-ROM jp CALSLT 3/ ; Quit your DOS program and launch the AUTOEXEC.BAS under BASIC CALSLT equ 001Ch BASENT equ 04022h REBOOT equ 0F340h TEMPST equ 0F67Ah MASTER equ 0F348h org 0100h ld a,0 ; 0 to run the AUTOEXEC.BAS file ld (REBOOT),a ld ix,(TEMPST) ; Erases 3 bytes ld (ix),0 ; from the ld (ix+1),0 ; area reserved for ld (ix+2),0 ; the BASIC program ld ix,BASENT ld iy,(MASTER-1) ; Slot of the Master Disk-ROM jp CALSLT |
4025H (FORMTM)
| Effect: | Format a disk in BASIC by asking the user for settings. This routine sets the Carry flag to 1 and then calls the FORMTK (04026h) routine below. |
| Input: | None |
| Output: | None |
| Note: | This is interactive process with user (prompts for drive and format choice) |
4026H (FORMTM)
| Effect: | Format a disk from a program with user-specified parameters. |
| Input: | F = Reset the Carry flag HL = Start of buffer BC = Size of buffer |
| Output: | None |
4029H (MTOFF)
| Effect: | Stop all drives of all controllers |
| Input: | None |
| Output: | None |
| Modify: | AF, BC, DE, HL, IX et IY. |
| Note: | This routine only exists if the interface manages removable disks. Otherwise, 04029h will contain the zero byte (00h). Some HDD interfaces have wrongly implemented this as a HDD powerdown (HSH/MAK) |
402DH (GETSLT)
| Effect: | Get slot ID of disk ROM |
| Input: | None |
| Output: | A = Slot ID |
4030H
| Effect: | Get MSX-DOS system bottom |
| Input: | None |
| Output: | HL = Lowest address used by the base MSX-DOS system |