Epson S1C33210 manual 166

II CORE BLOCK: BCU (Bus Control Unit)

Little-endian

31

Destination (general-purpose register)

0

Bus operation

Sign or Zero extension

Byte 1

Byte 0

No.

A1

A0

#WRH #WRL 15

Data bus

0

15

1

0

1

∗

0

1

1

Byte 1

Byte 0

A[1:0]=∗ 0

Source (16-bit device)

Big-endian

31Destination (general-purpose register)

Sign or Zero extension	Byte 1	Byte 0
	15	1

A[1:0]=∗ 0

Source (16-bit device)

0

0

Bus operation

No.	A1	A0	#WRH #WRL 15		Data bus		0
1	∗	0	1	1	Byte 1	Byte 0

Figure 4.8 Half-word Data Reading from a 16-bit Device

Little-endian

31		Source (general-purpose register)						0
	Byte 3		Byte 2	Byte 1		Byte 0
				15	1			0
							1'
				A[1:0]=∗ 1	A[1:0]=∗ 0

Destination (16-bit device)

Big-endian

Bus operation

No.	A1	A0	#WRH #WRL		15	Data bus		0
1	∗	1	0	1		Byte 0	Data retained
1'	∗	0	1	0	Data retained		Byte 0

31		Source (general-purpose register)						0
	Byte 3		Byte 2	Byte 1		Byte 0
				15	1			0
							1'
				A[1:0]=∗ 0	A[1:0]=∗ 1

Destination (16-bit device)

Bus operation

No.	A1	A0	#WRH #WRL		15	Data bus		0
1	∗	0	0	1		Byte 0	Data retained
1'	∗	1	1	0	Data retained		Byte 0

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

B-II-4-14 EPSON S1C33210 FUNCTION PART