Register: 0x01 (0x81)

SCSI Control One (SCNTL1)

Read/Write

7

6

5

4

3

 

2

1

 

0

EXC

ADB

 

DHP

CON

RST

 

AESP

IARB

 

SST

 

 

 

 

 

 

 

 

 

 

 

0

0

 

0

0

0

 

0

0

 

0

 

 

 

 

 

 

 

 

 

 

EXC

 

Extra Clock Cycle of Data Setup

 

 

7

 

 

When this bit is set, an extra clock period of data setup

 

 

is added to each SCSI data transfer. The extra data setup

 

 

time can provide additional system design margin, though

 

 

it affects the SCSI transfer rates. Clearing this bit disables

 

 

the extra clock cycle of data setup time. Setting this bit

 

 

only affects SCSI send operations.

 

 

 

ADB

 

Assert SCSI Data Bus

 

 

 

6

 

 

When this bit is set, the LSI53C810A drives the contents

 

 

of the SCSI Output Data Latch (SODL) register onto the

 

 

SCSI data bus. When the LSI53C810A is an initiator, the

 

 

SCSI I/O signal must be inactive to assert the SCSI Out-

 

 

put Data Latch (SODL) contents onto the SCSI bus.

 

 

When the LSI53C810A is a target, the SCSI I/O signal

 

 

must be active to assert the SCSI Output Data Latch

 

 

(SODL) contents onto the SCSI bus. The contents of the

 

 

SCSI Output Data Latch (SODL) register can be asserted

 

 

at any time, even before the LSI53C810A is connected to

 

 

the SCSI bus. Clear this bit when executing SCSI

 

 

 

SCRIPTS. It is normally used only for diagnostics testing

 

 

or operation in low level mode.

 

 

 

 

DHP

 

Disable Halt on Parity Error or ATN (Target Only) 5

 

 

The DHP bit is only defined for target mode. When this

 

 

bit is cleared, the LSI53C810A halts the SCSI data

 

 

transfer when a parity error is detected or when the

 

 

SATN/ signal is asserted. If SATN/ or a parity error is

 

 

received in the middle of a data transfer, the LSI53C810A

 

 

may transfer up to three additional bytes before halting to

synchronize between internal core cells. During synchronous operation, the LSI53C810A transfers data until there are no outstanding synchronous offsets. If the LSI53C810A is receiving data, any data residing in the DMA FIFO is sent to memory before halting.

5-6

Operating Registers

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LSI 53C810A technical manual Register 0x01, Exc, Adb, Dhp