82091AA Datasheet, PDF (142/204 Pages) Intel Corporation – ADVANCED INTEGRATED PERIPHERAL (AIP)

82091AA
Symbol
FD0 FD1
GAP
GPL
H HDS
HLT
HUT
ISO
LOCK
MFM
Description
FLOPPY DRIVE SELECT These two bits select which physical drive is being specified The
FDn corresponds to FDSn and FDMEn on the floppy drive interface The drive is selected
independent of the BOOTSEL bit in the TDR Refer to Section 8 1 3 TDR Enhanced Tape
Drive Register which explains the distinction between physical drives and their virtual map-
ping as defined by the BOOTSEL bit
FD1 FD0 Drive slot
0
0
drive 0
1
0
drive 1
0
1
drive 2
1
1
drive 3
Available if the four floppy drive option is selected in the FCFG1 Register
GAP Alters Gap 2 length when using Perpendicular Mode
GAP LENGTH The gap 3 size (Gap 3 is the space between sectors excluding the VCO
synchronization field)
HEAD ADDRESS Selected head 0 or 1 (disk side 0 or 1) as encoded in the sector ID field
HEAD LOAD TIME The time interval that FDC waits after loading the head and before
initiating a read or write operation Refer to the SPECIFY Command for actual delays
HEAD UNLOAD TIME The time interval from the end of the execution phase (of a read or
write command) until the head is unloaded Refer to the SPECIFY Command for actual
delays
ISO FORMAT When ISO^e1 the ISO format is used for all data transfer commands When
ISO^e0 the normal IBM system 34 and perpendicular is used The default is ISO^e0
LOCK Lock defines whether EFIFO FIFOTHR and PRETRK parameters of the CONFIG-
URE Command can be reset to their default values by a software reset (Reset made by
setting the proper bit in the DSR or DOR registers)
MFM MODE A one selects the double density (MFM) mode A zero is reserved
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