HP Vectra Technical Reference Manual page 253

• If
this is the last hard disc driver in the chain and the requested physical device number is
larger than this disc driver's number then it will return a bad command error.
8.2 Data Structures
There are separate data structures for the hard disc and the flexible disc drivers. The flexible disc
has three data structures. The diskette parameter table holds information necessary for
initializing and supporting the
NEe
flexible disc controller chip. The diskette status table holds
information about the status of the previous flexible disc operation. The diskette operation table
contains various disc operating parameters such as drive status, flexible disc data transfer rate,
etc. The hard disc has only one data structure. However, each hard disc driver maintains it's own
copy. The hard disc parameter table is similar to the flexible diskette status table. It contains the
physical device characteristics for a particular hard disc attached to the system.
8.2.1 Diskette Operation Table
The diskette operation table is located in the 5TD-8105 data area starting at memory location
0040:008BH (0048BH). It contains parameters used by the disc driver to perform its functions.
Data stored in this table allow the high capacity drives to read or write either standard or high
capacity flexible discs. The contents of the operating parameter table are listed in table 8.1 .
Table 8.1
Diskette Operation Table
Offset
8SH
8FH
90H
92H
94H
244 Disc
Length
in Bytes
1
1
2
2
2
Description
Data transfer rate of previous operation
Bit 0 is set to '1' for combined 360kb/1.2Mb diskette controller.
Current media type table
Work area to generate current media types
Table of current head positions