Epson S1C33L03 manual 191

II CORE BLOCK: BCU (Bus Control Unit)

Little-endian

31			Source (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
							15					1		1'			0	1		∗	1	0	1		Byte 0	Data retained
																		1'		∗	0	1	0	Data retained		Byte 0
									A[1:0]=∗ 1			A[1:0]=∗ 0
								Destination (16-bit device)
	Big-endian
31			Source (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
							15					1		1'			0	1		∗	0	0	1		Byte 0	Data retained
																		1'		∗	1	1	0	Data retained		Byte 0
									A[1:0]=∗ 0			A[1:0]=∗ 1
								Destination (16-bit device)
									Figure 4.9			Byte Data Writing to a 16-bit Device
	Little-endian
31			Destination (general-purpose register)														0						Bus operation
			Sign or Zero extension									RD byte							No.	A1	A0	#WRH #WRL		15	Data bus		0
							15					1			1'		0	1		∗	1	1	1		RD byte	Ignored
																		1'		∗	0	1	1		Ignored	RD byte
									A[1:0]=∗ 1			A[1:0]=∗ 0
									Source (16-bit device)
	Big-endian
31			Destination (general-purpose register)														0						Bus operation
			Sign or Zero extension									RD byte							No.	A1	A0	#WRH #WRL		15	Data bus		0
							15					1			1'		0	1		∗	0	1	1		RD byte	Ignored
																		1'		∗	1	1	1		Ignored	RD byte
									A[1:0]=∗ 0			A[1:0]=∗ 1
									Source (16-bit device)
									Figure 4.10 Byte Data Reading from a 16-bit Device
	Little-endian
31			Source (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
8			4	0 8		3	0 8			2	0 8					1	0		1	0	0	X	0	Data retained		Byte 0
																		2		0	1	X	0	Data retained		Byte 1
		A[1:0]=11			A[1:0]=10				A[1:0]=01			A[1:0]=00
																		3		1	0	X	0	Data retained		Byte 2
					Destination (8-bit device)
																		4		1	1	X	0	Data retained		Byte 3
	Big-endian																							(X: Not connected/Unused)
31			Source (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
8			1	0 8		2	0 8			3	0 8					4	0		1	0	0	0	1		Byte 3	Data retained
																		2		0	1	0	1		Byte 2	Data retained
		A[1:0]=00			A[1:0]=01				A[1:0]=10			A[1:0]=11
																		3		1	0	0	1		Byte 1	Data retained
					Destination (8-bit device)
																		4		1	1	0	1		Byte 0	Data retained
									Figure 4.11			Word Data Writing to an 8-bit Device
	Little-endian
31			Destination (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
8			4	0 8		3	0 8			2	0 8					1	0		1	0	0	X	1		Ignored	Byte 0
																		2		0	1	X	1		Ignored	Byte 1
		A[1:0]=11			A[1:0]=10				A[1:0]=01			A[1:0]=00
																		3		1	0	X	1		Ignored	Byte 2
					Source (8-bit device)
																		4		1	1	X	1		Ignored	Byte 3
	Big-endian																							(X: Not connected/Unused)
31			Destination (general-purpose register)														0						Bus operation
		Byte 3			Byte 2				Byte 1				Byte 0						No.	A1	A0	#WRH #WRL		15	Data bus		0
8			1	0 8		2	0 8			3	0 8					4	0		1	0	0	1	1		Byte 3	Ignored
																		2		0	1	1	1		Byte 2	Ignored
		A[1:0]=00			A[1:0]=01				A[1:0]=10			A[1:0]=11
																		3		1	0	1	1		Byte 1	Ignored
					Source (8-bit device)
																		4		1	1	1	1		Byte 0	Ignored

Figure 4.12 Word Data Reading from an 8-bit Device

A-1

B-II

BCU

S1C33L03 FUNCTION PART EPSON B-II-4-15