User’s Guide 21020285 D
Chapter 4 Command Operation
Single Command Structure Page 4 - 9
Single Command Structure
There are two ways to issue a command to the RF3880 adapter. The simplest
method involves the use of the Single Command structure. This 52-byte
structure combines a Parameter Block and a Status Block into a sin gle structure
along with a field that specifies an interrupt level and ID. This Single Command
structure is shown below. The important things to remember about the Sin gle
Command structure are:
• It is designed to be used for initial set-up.
• The first command you issue to the board after power-up or reset must
use this structure.
Format of
Single
Command
Structure
The Single Command structure is illustrated for you below:
Parameter Block
This section of the Single Command structure is where you build a Parameter
Block containing information related to the command you wish to execute:
Initiator Pass-through or Board-control.
Most of the fields are command-specific; if there is data to transfer, for example,
an address, address modifier and transfer count must be provided. For details
about the parameter block fields necessary for a Initiator Pass-through
command refer to Chapter 5, Initiator Pass-through Commands and a SCSI
specification. For details about a Board-control command see Chapt er 7, Board-
control Commands.
Reserved Fields
Reserved fields must be zeroed. If a non-zero value is permitted in a Reser ved
block, you may get an error.
Address
Offset Byte Memory Address
Offset +0 Offset +1 Offset +2 Offset +3
00H
Parameter Block
(detail for Initiator Pass-through commands on page 5 - 3,
see Chapter 7 for details on individual Board-control commands.)
04H
08H
0CH
10H
14H
18H
1CH Reserved Reserved
20H Reserved
24H Status Block
(detail for Initiator Pass-through status on page 5 - 12,
see Chapter 7 for detail on individual Board-control status.)
28H
2CH
30H
Table 20: Single Command Structure