LSI 53C810A technical manual Transfer Control Instructions, First Dword

Table 6.2	Read/Write Instructions
	Opcode 111	Opcode 110	Opcode 101
Operator	Read-Modify-Write	Move to SFBR	Move from SFBR
110	Add data to register without	Add data to register without	Add data to SFBR without
	carry and place the result	carry and place the result in	carry and place the result in
	in the same register.	the SCSI First Byte	the register. Syntax: “Move
	Syntax: “Move RegA +	Received (SFBR) register.	SFBR + data8 to RegA”
	data8 to RegA”	Syntax: “Move RegA + data8
		to SFBR”
111	Add data to register with	Add data to register with	Add data to SFBR with carry
	carry and place the result	carry and place the result in	and place the result in the
	in the same register.	the SCSI First Byte	register. Syntax: “Move
	Syntax: “Move RegA +	Received (SFBR) register.	SFBR + data8 to RegA with
	data8 to RegA with carry”	Syntax: “Move RegA + data8	carry”
		to SFBR with carry”

1. Data is shifted through the Carry bit and the Carry bit is shifted into the data byte. Miscellaneous Notes:

˘Substitute the desired register name or address for “RegA” in the syntax examples.

˘data8 indicates eight bits of data.

6.6 Transfer Control Instructions

The Transfer Control, or Conditional Jump, instruction allows you to write SCRIPTS that make decisions based on real time conditions on the SCSI bus, such as phase or data. This instruction type includes Jump, Call, Return, and Interrupt instructions.

6.6.1 First Dword

IT[2:0]	Instruction Type -
	Transfer Control Instruction	[31:30]
OPC[2:0]	OpCode	[29:27]

This 3-bit field specifies the type of transfer control instruction to execute. All transfer control instructions can be conditional. They can be dependent on a true/false comparison of the ALU Carry bit or a comparison of the SCSI information transfer phase with the Phase field, and/or a comparison of the First Byte Received with the Data Compare field. Each instruction can operate in Initiator or Target mode.

Transfer Control Instructions 6-27