Register: 0x0B (0x8B)

SCSI Bus Control Lines (SBCL)

Read Only

7

6

5

 

4

3

2

1

0

REQ

ACK

 

BSY

 

SEL

ATN

MSG

C/D

I/O

 

 

 

 

 

 

 

 

 

 

x

x

 

x

 

x

x

x

x

x

 

 

 

 

 

 

 

 

 

 

REQ

 

SREQ/ Status

 

 

 

 

7

ACK

 

SACK/ Status

 

 

 

 

6

BSY

 

SBSY/ Status

 

 

 

 

5

SEL

 

SSEL/ Status

 

 

 

 

4

ATN

 

SATN/ Status

 

 

 

 

3

MSG

 

SMSG/ Status

 

 

 

2

C/D

 

SC_D/ Status

 

 

 

 

1

I/O

 

SI_O/ Status

 

 

 

 

0

This register returns the SCSI control line status. A bit is set when the corresponding SCSI control line is asserted. These bits are not latched; they are a true representation of what is on the SCSI bus at the time the register is read. The resulting read data is synchronized before being presented to the PCI bus to prevent parity errors from being passed to the system. This register is used for diagnostics testing or operation in low level mode.

Register: 0x0C (0x8C)

DMA Status (DSTAT)

Read Only

7

6

5

4

3

2

1

0

DFE

MDPE

BF

ABRT

SSI

SIR

R

IID

1

0

0

0

0

0

x

0

 

 

 

 

 

 

 

 

Reading this register clears any bits that are set at the time the register is read, but does not necessarily clear the register in case additional interrupts are pending (the LSI53C810A stacks interrupts). The DIP bit

5-20

Operating Registers

Page 94
Image 94
LSI 53C810A technical manual Register 0x0B 0x8B, Register 0x0C 0x8C