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11 chained block moves, Chained block moves, Block move and chained block move instructions – Avago Technologies LSI53C876E User Manual

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Functional Description

2.2.11 Chained Block Moves

Since the LSI53C876 has the capability to transfer 16-bit wide SCSI
data, a unique situation occurs when dealing with odd bytes. The
chained move (CHMOV) SCRIPTS instruction along with the Wide SCSI
Send (WSS) and Wide SCSI Receive (WSR) bits in the

SCSI Control

Two (SCNTL2)

register are used to facilitate these situations. The

Chained Block Move instruction is illustrated in

Figure 2.8

.

Figure 2.8

Block Move and Chained Block Move Instructions

CHMOV 5, 3 when Data_Out

Moves five bytes from address 0x03 in the host memory to the SCSI bus.
Bytes 0x03, 0x04, 0x05, and 0x06 are moved and byte 0x07 remains in
the low-order byte of the

SCSI Output Data Latch (SODL)

register and

is combined with the first byte of the following MOVE instruction.

Move 5, 9 when Data_Out

Moves five bytes from address 0x09 in the host memory to the SCSI bus.

0x03

0x02

0x01

0x00

0x07

0x06

0x05

0x04

0x0B 0x0A

0x09

0x08

0x0F

0x0E 0x0D 0x0C

0x13

0x12

0x11

0x10

0x04

0x03

0x06

0x05

0x09

0x07

0x0B 0x0A

0x0D 0x0C

32 Bits

16 Bits

Host Memory

SCSI Bus

00

04

08

0C

10