@CHIP-RTOS - External Disk Interface

IPC@CHIP® Documentation Index

Here is the low-level software-interrupt-based API for an external disk B: and D: drive.   This interface allows you to add an external B: or D: drive.   This drive must be block (sector) oriented.   Each sector should be 512 bytes long.   The application must provide a software interrupt 0xB1 function for drive B: or 0xB2 for drive D: to read and write these sectors on this drive.

On SC1x systems, the maximum disk size is about 2 Gigabytes.   (This limitation is due to the FAT16 disk format used on SC1x systems.)   SC1x systems support only drive B:

The SC1x3/SC2x systems support FAT32 format. The maximum disk size on SC1x3/SC2x systems is about 8 Terabytes.   The maximum file size is 2**32 bytes minus one cluster (=32 kbyte), which is about 4 Gigabyte.   SC1x3/SC2x systems support drive B: and drive D:.

Interrupt 0xB0 Services

Service is selected by index in AH register.

0x01:_Install External Disk B:

0x02:_Deinstall External Disk B:

0x03:_Install a notification callback function

0x04:_Uninstall the notification callback function

0x05:_Install External Disk D:

0x06:_Deinstall External Disk D:

Interrupt 0xB0 service 0x01: Install External Disk B:

This function will logically install a B: drive.
Prior to this call the application must provide a disk read/write function installed at interrupt 0xB1. This installed handler function should expect:

AX       1 for write, 0 for read.
BX,DX    Sector number (BX is MSH of unsigned long)
CX       Number of sectors to read/write
ES:DI    Segment:Offset of memory area to read/write

The handler should return 0 in AX if OK.

Parameters

AH: 0x01
BX,DX: An unsigned long with the total number of sectors. BX holds high word.

Return Value

AX is 0 if OK.

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x V1.00 V1.00 V1.00 V0.90 V1.00

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Interrupt 0xB0 service 0x02: Deinstall External Disk B:

Used to deinstall drive B: which was installed before with function 0x01 (above).

Parameters

AH: 0x02

Return Value

AX =0 success
AX !=0 failed (may be drive was not installed?)

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x V1.00 V1.00 V1.00 V0.90 V1.00

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Interrupt 0xB0 service 0x03: Install a notification callback function

The external drives B: and D: may be hot-plugable. This means that the drive medium might be removed or inserted while your application is running. In some cases it may be important for you to be notified if a medium is removed or inserted, for example if one of your tasks has set its working directory to the external drive. By default @CHIP-RTOS will reset the working directory of all tasks that previously had their working directory on a drive that has been removed to A:\. However this might not be appropriate. So a reaction on the removal of a hot-pluggable medium might be to set a new valid working directory.
To be notified of insertion and removal events, install an EXTDISK callback function.

A maximum of 12 EXTDISK callback functions can be installed.

The following events may be passed along with the callback function's event parameter:
EXTDISK_EVENT_INSTALL_B = 0x01

Drive B: has been installed
EXTDISK_EVENT_REMOVE_B = 0x02

Drive B: has been uninstalled
EXTDISK_EVENT_INSTALL_D = 0x03

Drive D: has been installed
EXTDISK_EVENT_REMOVE_D = 0x04

Drive D: has been uninstalled

Parameters

AH

0x03

ES:DI

Pointer to the callback function of the type EXTDISK_CALLBACK

EXTDISK_CALLBACK is defined as follows:

typedef void (far * EXTDISK_CALLBACK)(unsigned int event);

Return Value

AX =0 success
AX !=0 failed

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x V1.20 V1.20 V1.20 V1.07 V1.00

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Interrupt 0xB0 service 0x04: Uninstall the notification callback function

Uninstall the notification callback function

Parameters

AH: 0x04
ES:DI: Pointer to the callback function of the type EXTDISK_CALLBACK (see Install a notification callback function for details)

Return Value

AX =0 success
AX !=0 failed

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x V1.20 V1.20 V1.20 V1.05 V1.00

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Interrupt 0xB0 service 0x05: Install External Disk D:

This function will logically install a D: drive.
Prior to this call the application must provide a disk read/write function installed at interrupt 0xB2. This installed handler function should expect:

AX       1 for write, 0 for read.
BX,DX    Sector number (BX is MSH of unsigned long)
CX       Number of sectors to read/write
ES:DI    Segment:Offset of memory area to read/write

The handler should return 0 in AX if OK.

Parameters

AH: 0x05
BX,DX: An unsigned long with the total number of sectors. BX holds high word.

Return Value

AX is 0 if OK.

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x n/a n/a n/a V1.07 V1.00

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Interrupt 0xB0 service 0x06: Deinstall External Disk D:

Used to deinstall drive D: which was installed before with function 0x05 (above).

Parameters

AH: 0x06

Return Value

AX =0 success
AX !=0 failed (may be drive was not installed?)

Supported since or modified in @CHIP-RTOS version

SC12 SC13 SC11 SC1x3 SC2x n/a n/a n/a V1.07 V1.00

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