1 - DD_INTERFACE

Synopsys

Is the floppy disk drive interface present?

This information is also held by BASIC in bit 4 of the FLAGS3 system variable.

Entry Parameters

None

Exit Parameters

If present

Carry true

Otherwise:

Carry false

Always:

A BC DE HL IX corrupt, all other registers preserved.

2 - DD_INIT

Synopsys

Initialise the disk driver

Entry Parameters

None

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.

3 - DD_SETUP

Synopsys

Set up disk parameters. Send a specify command.

Entry Parameters

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.

4 - DD_SET_RETRY

Synopsys

Set the try and retry count. A value of 1 will try the operation once with no retries.

Entry Parameters

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.

5 - DD_READ_SECTOR

Synopsys

Read a sector

Entry Parameters

Exit Parameters

If OK:

Carry true

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

6 - DD_WRITE_SECTOR

Synopsys

Write a sector

Entry Parameters

Exit Parameters

If OK:

Carry true

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

7 - DD_CHECK_SECTOR

Synopsys

Check a sector. (Uses the uPD765A scan equal command.)

Checks that the sector on disk is the same as the copy in memory.

Note that FFh (255) on disk or in memory always matches anything (see uPD765A specification for further details).

Entry Parameters

Exit Parameters

If OK & Equal:

Carry true

Zero true

A corrupt

If OK & Not Equal:

Carry true

Zero false

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

8 - DD_FORMAT

Synopsys

Format a track. (Uses the uPD765A format track command.)

Entry Parameters

Exit Parameters

If OK:

Carry true

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

Format buffer

The format buffer contains 4 bytes for each sector:

9 - DD_READ_ID

Synopsys

Read a sector identifier

Entry Parameters

Exit Parameters

If OK:

Carry true

A = sector number from identifier

Otherwise:

Carry false

A = Error code

Always:

HL = Address of result buffer in page 7

BC DE IX corrupt, all other registers preserved.

10 - DD_TEST_UNSUITABLE

Synopsys

Check that disk is suitable to write to. A single track disk will not work in a double track drive, and vice versa.

Entry Parameters

Exit Parameters

If OK:

Carry true

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

11 - DD_LOGIN

Synopsys

Log in a new disk. Initialise the XDPB. This routine does not affect or consider the freeze flag.

Entry Parameters

Exit Parameters

If OK:

Carry true

A = Disk type

DE = Size of allocation vector

HL = Size of hash table

Otherwise:

Carry false

A = Error code

DE HL corrupt

Always:

BC IX corrupt, all other registers preserved.

12 - DD_SEL_FORMAT

Synopsys

Initialise an XDPB for a standard format. This routine does not affect or consider the freeze flag.

Entry Parameters

Exit Parameters

If OK:

Carry true

A = Disk type

DE = Size of 2 bit allocation vector

HL = Size of hash table

Otherwise:

Carry false

A = Error code

DE HL corrupt

Always:

BC IX corrupt, all other registers preserved.

13 - DD_ASK_1

Synopsys

Check to see if unit 1 is present. BASIC holds this information in bit 5 of the FLAGS3 system variable.

Turn motor on.

Fetch drive status.

If unit 1 is not-ready and write-protected, then unit 1 is missing. Start motor off timeout.

Note that this routine can be fooled by disks which are almost, but not quite, inserted in the drive.

This routine assumes that when a disk is not in the drive, then write-protect is true. This is indeed the case for 3 inch and 8 inch disk drives, but is not the case for 5 1/4 inch disk drives.

Entry Parameters

None

Exit Parameters

If unit 1 present:

Carry true

Otherwise:

Carry false

Always:

A BC DE HL IX corrupt, all other registers preserved.

14 - DD_DRIVE_STATUS

Synopsys

Issue a sense drive status command.

Entry Parameters

Exit Parameters

A = ST3 status register 3 of uPD765A

Always:

F BC DE HL IX corrupt, all other registers preserved.

15 - DD_EQUIPMENT

Synopsys

Ask what type of drive this is (i.e. single/double track, single/double sided).

Track information can only be determined once a disk has been seen and had its type identified during logging in.

Side information can only be detected after a double sided disk has been seen and has its type identified during logging in.

Entry Parameters

Exit Parameters

Carry true

A = Side/track information
bits 0…1 side information: 0 = unknown, 1 = single sided, 2 = double sided
bits 2…3 track information: 0 = unknown, 1 = single track, 2 = double track

Always:

F BC DE HL IX corrupt, all other registers preserved.

16 - DD_ENCODE

Synopsys

Set the copy protection ENCODE subroutine.

Copy protected disks have some of their track and sector numbers encoded on disk. Before each disk access, the ENCODE subroutine is called to encode the physical track and sector numbers.

These encoded track and sector numbers must match those in the sector identifier.

Note that tracks 0…2 on either side of a disk should not be encoded.

Entry Parameters

Exit Parameters

HL = Address of previous encode routine, 0 if none

Always:

AF BC DE IX corrupt, all other registers preserved.

ENCODE routine

If you are substituting your own ENCODE subroutine, the 'entry conditions' are the conditions passed to your subroutine, and the 'exit conditions' are the values that your subroutine must produce and the registers you are allowed to corrupt.

Entry Parameters

Exit Parameters

D = Encoded physical track

E = Encoded physical sector

Always:

AF corrupt, all other registers preserved.

17 - DD_L_XDPB

Synopsys

Initialise an XDPB for a given format.

This routine does not affect or consider the freeze flag.

Entry Parameters

Exit Parameters

If OK:

Carry true

A = Disk type recorded on disk

DE = Size of allocation vector

HL = Size of hash table

Otherwise:

Carry false

A = Error code

DE HL corrupt

Always:

BC IX corrupt, all other registers preserved.

18 - DD_L_DPB

Synopsys

Initialise an DPB for a given format.

This routine does not affect or consider the freeze flag.

Entry Parameters

Exit Parameters

If OK:

Carry true

A = Disk type recorded on disk

DE = Size of allocation vector

HL = Size of hash table

Otherwise:

Carry false

A = Error code

DE HL corrupt

Always:

BC IX corrupt, all other registers preserved.

19 - DD_L_SEEK

Synopsys

Seek to required track. Retry if failure.

Entry Parameters

Exit Parameters

If OK:

Carry true

A corrupt

Otherwise:

Carry false

A = Error code

Always:

BC DE HL IX corrupt, all other registers preserved.

20 - DD_L_READ

Synopsys

Low level uPD765A read command.

• Read data.
• Read deleted data.
• Read a track.
• Writes commands.
• Reads data.
• Reads results.
• Motor must be running.

Entry Parameters

Exit Parameters

HL = Address of result buffer in page 7

Always:

AF BC DE IX corrupt, all other registers preserved.

21 - DD_L_WRITE

Synopsys

Low level uPD765A write command.

• Write data.
• Write deleted data.
• Format a track.
• Scan equal.
• Scan low or Equal.
• Writes commands.
• Writes data.
• Reads results.
• Motor must be running.

Entry Parameters

Exit Parameters

HL = Address of result buffer in page 7

Always:

AF BC DE IX corrupt, all other registers preserved.

22 - DD_L_ON_MOTOR

Synopsys

Turn on the motor. Wait for the motor on time as set by DD SETUP.

Entry Parameters

None

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.

23 - DD_L_T_OFF_MOTOR

Synopsys

Start motor off timeout.

Entry Parameters

None

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.

24 - DD_L_OFF_MOTOR

Synopsys

Turn off the motor.

Entry Parameters

None

Exit Parameters

Always:

AF BC DE HL IX corrupt, all other registers preserved.