PS/2 Mode
7
6
5
4
3
2
1
0
DSK
1
1
1
1 DRATE DRATE nHIGH
CHG
SEL1 SEL0 nDENS
RESET N/A N/A N/A N/A N/A N/A N/A
1
COND.
BIT 0 nHIGH DENS
This bit is low whenever the 500 Kbps or 1 Mbps data rates are selected, and high when 250 Kbps and
300 Kbps are selected.
BITS 1 - 2 DATA RATE SELECT
These bits control the data rate of the floppy controller. See Table 13 for the settings corresponding to
the individual data rates. The data rate select bits are unaffected by a software reset, and are set to
250 Kbps after a hardware reset.
BITS 3 - 6 UNDEFINED
Always read as a logic "1"
BIT 7 DSKCHG
This bit monitors the pin of the same name and reflects the opposite value seen on the disk cable or
the value programmed in the Force Disk Change Register (see Runtime Register 1E[1:0]).
Model 30 Mode
7
6
5
4
3
2
1
0
DSK
0
0
0 DMAEN NOPREC DRATE DRATE
CHG
SEL1 SEL0
RESET N/A
0
0
0
0
0
1
0
COND.
BITS 0 - 1 DATA RATE SELECT
These bits control the data rate of the floppy controller. See Table 13 for the settings corresponding to
the individual data rates. The data rate select bits are unaffected by a software reset, and are set to
250 Kbps after a hardware reset.
BIT 2 NOPREC
This bit reflects the value of NOPREC bit set in the CCR register.
BIT 3 DMAEN
This bit reflects the value of DMAEN bit set in the DOR register bit 3.
BITS 4 - 6 UNDEFINED
Always read as a logic "0"
BIT 7 DSKCHG
This bit monitors the pin of the same name and reflects the opposite value seen on the disk cable or
the value programmed in the Force Disk Change Register (see Runtime Register at offset 0x1E).
35