Drive Type ID, Bits 4 - 5
The Drive Type ID bits depend on the last drive selected in the Digital Output Register and the Drive Type IDs that
are programmed in configuration register 6 (Table 18).
Table 18 - Drive Type ID
DIGITAL OUTPUT REGISTER
TDR - DRIVE TYPE ID
Bit 1
Bit 0
Bit 5
Bit 4
0
0
1
1
0
1
0
1
CR6 - Bit 1
CR6 - Bit 3
CR6 - Bit 5
CR6 - Bit 7
CR6 - Bit 0
CR6 - Bit 2
CR6 - Bit 4
CR6 - Bit 6
Floppy Boot Drive, Bits 2 - 3
The Floppy Boot Drive bits come from Configuration Register 7: TDR Bit 3 = CR7 Bit 1; TDR Bit 2 = CR7 Bit 0.
Tape Drive Select, Bits 0 - 1
The Tape Drive Select bits are the same as in Normal mode. These bits are Read/Write.
MAIN STATUS REGISTER (MSR)
The Main Status Register (Base Address + 4: Read-only) indicates the status of the disk controller (Table 19). The
Main Status Register is valid in all modes and can be read at any time. The MSR indicates when the disk controller is
ready to receive data via the Data Register. It should be read before transferring each byte to or from the data
register, except in DMA mode. No delay is required when reading the MSR after a data transfer.
Table 19 - Main Status Register
7
6
5
4
3
2
1
0
MSR
RQM
DIO
NON DMA
CMD
BUSY
DRV3
BUSY
DRV2
BUSY
DRV1
BUSY
DRV0
BUSY
DRVx Busy, Bits 0 - 3
These bits are set to a “1” when a drive is in the seek portion of a command, including implied and overlapped seeks
and recalibrates.
Command Busy, Bit 4
This bit is set to a “1” when a command is in progress. This bit will go active after the command byte has been
accepted and goes inactive at the end of the results phase. If there is no result phase (Seek, Recalibrate
commands), this bit is returned to a “0” after the last command byte.
Non-DMA, Bit 5
This mode is selected in the SPECIFY command and will be set to a “1” during the execution phase of a command.
This is for polled data transfers and helps to differentiate between the data transfer phase and the reading of result
bytes.
DIO, Bit 6
Indicates the direction of a data transfer once an RQM is set. A “1” indicates a read and a “0” indicates a write is
required.
RQM, Bit 7
Indicates that the host can transfer data if set to a “1”. No access is permitted if set to a “0”.
SMSC DS – FDC37N769
Page 23 of 137
Rev. 02-16-07
DATASHEET
SMSC [ SMSC CORPORATION ]
