Product specifications

VT1211 LPC SuperIO and Hardware Monitor
Revision 1.0 January 8, 2002 -28- Register Descriptions – Floppy Disk Controller I/O
Technologies, Inc.
We Connect
We ConnectWe Connect
We Connect
I/O Space Registers
Floppy Disk Controller I/O Registers
These registers are normally accessed at standard FDC I/O
port addresses 3F0-3F7h (see LDN 0 Rx61-60 for the FDC
Port I/O Base setting).
Offset 2 – FDC Command................................................RW
7 Motor 3 (unused in VT82C686B: no MTR3# pin)
6 Motor 2 (unused in VT82C686B: no MTR2# pin)
5 Motor 1
0 Motor Off
1 Motor On
4 Motor 0
0 Motor Off
1 Motor On
3 DMA and IRQ Channels
0Disable
1 Enable
2 FDC Reset
0 Execute FDC Reset
1FDCEnable
1-0 Drive Select
00 Select Drive 0
01 Select Drive 1
1x -reserved-
Offset 4 – FDC Main Status..............................................RO
7 Main Request
0 Data register not ready
1 Data register ready
6 Data Input / Output
0 CPU => FDC
1FDC=>CPU
5 Non-DMA Mode
0 FDC in DMA mode
1 FDC not in DMA mode
4FDCBusy
0 FDC inactive
1 FDC active
3-2 Reserved ........................................ always reads 0
1 Drive 1 Active
0 Drive inactive
1 Drive performing a positioning change
0 Drive 0 Active
0 Drive inactive
1 Drive performing a positioning change
Offset 4 – FDC Data Rate Select ..................................... WO
7 Software Reset
0 Normal operation................................... default
1 Execute FDC reset (this bit is self clearing)
6PowerDown
0 Normal operation................................... default
1 Power down FDC logic
5 Reserved ........................................always reads 0
4-2 Precompensation Select
Selects the amount of write precompensation to be
used on the WDATA output:
000 Default................................................... default
001 41.7 ns
010 93.3 ns
011 125.0 ns
100 166.7 ns
101 208.3 ns
110 250.0 ns
111 0.0 ns (disable)
1-0 Data Rate
MFM
FM Drive Type
00 500K 250K bps 1.2MB 5” or 1.44 MB 3”
01 300K 150K bps 360KB 5”
10 250K 125K bps 720KB 3” ................ default
11 1M illegalbps
Note: these bits are not changed by software reset
Offset 5 – FDC Data ......................................................... RW
Offset 7 – FDC Disk Change Status................................ RW
7 Disk Change......................................................... RO
0 Floppy not changed ............................... default
1 Floppy changed since last instruction
6-2 Undefined .....................................always reads 1’s
1-0 Data Rate ........................................................ WO
00 500 Kbit/sec (1.2MB 5” or 1.44 MB 3” drive)
01 300 Kbit/sec (360KB 5” drive)
10 250 Kbit/sec (720KB 3” drive)
11 1 Mbit/sec