Data Bytes

 

Running SLPAR

 

 

 

00000000

 

 

 

 

1. 11001100

11001100

(XOR of word 1)

 

 

 

2. 01010101

10011001

(XOR of word 1 and 2)

 

 

 

3. 00001111

10010110

(XOR of word 1, 2 and 3)

 

Even parity >>> 10010110

 

 

 

4. 10010110

00000000

 

 

 

 

A one in any bit position of the final SCSI Longitudinal Parity (SLPAR) value would indicate a transmission error.

The SCSI Longitudinal Parity (SLPAR) register is also used to generate the check bytes for SCSI send operations. If the SCSI Longitudinal Parity (SLPAR) register contains all zeros prior to sending a block move, it contains the appropriate check byte at the end of the block move. This byte must then be sent across the SCSI bus.

Note: Writing any value to this register resets it to zero.

The longitudinal parity checks are meant to provide an added measure of SCSI data integrity and are entirely optional. This register does not latch SCSI selection/ reselection IDs under any circumstances. The default value of this register is zero.

Register: 0x46 (0xC6)

Memory Access Control (MACNTL)

Read/Write

7

 

 

 

4

3

2

1

0

 

 

TYP[3:0]

 

DWR

DRD

PSCPT

SCPTS

 

 

 

 

 

 

 

 

 

0

1

 

1

0

0

0

0

0

 

 

 

 

 

 

 

 

 

TYP[3:0]

 

Chip Type

 

 

 

 

[7:4]

These bits identify the chip type for software purposes.

Bits 3 through 0 of this register are used to determine if an external bus master access is to local or far memory.

5-55

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Image 129
LSI 53C810A technical manual Register 0x46 0xC6, Memory Access Control Macntl Read/Write, TYP30 Chip Type