User`s guide

BDOS FUNCTION 44: SET MULTI-SECTOR COUNT

Entry Parameters:

Registers C: 2CH

E: Number of Sectors

Returned Value:

The Set Multi-Sector Count function provides logical record blocking under

CP/M 3. It enables a program to read and write from 1 to 128 records of 128 bytes

at a time during subsequent BDOS Read and Write functions.

Function 44 sets the Multi-Sector Count value for the calling program to the value

passed in register E. Once set, the specified Multi-Sector Count remains in effect until

the calling program makes another Set Multi-Sector Count function call and changes

the value. Note that the CCP sets the Multi-Sector Count to one when it initiates a

transient program.

The Multi-Sector Count affects BDOS error reporting for the BDOS Read and

Write functions. If an error interrupts these functions when the Multi-Sector is greater

than one, they return the number of records successfully read or written in register

H for all errors except for physical errors (A = 255).

Upon return, register A is set to zero if the specified value is in the range of 1 to

128. Otherwise, register A is set to 0FFH.

3-63

BDOS Function Calls CP/M 3 Programmers Guide