Epson S1C33L03 User Manual
II CORE BLOCK: BCU (Bus Control Unit)
S1C33L03 FUNCTION PART
EPSON
B-II-4-15
A-1
B-II
BCU
Byte 0
15
Data bus
0
#WRL
1
0
#WRH
0
1
A0
1
0
A1
∗
∗
∗
No.
1
1'
Data retained
Byte 0
Data retained
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=
∗
0
A[1:0]=
∗
1
0
1'
1
15
Source (general-purpose register)
Destination (16-bit device)
Bus operation
Little-endian
Byte 0
15
Data bus
0
#WRL
1
0
#WRH
0
1
A0
0
1
A1
∗
∗
∗
No.
1
1'
Data retained
Byte 0
Data retained
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=
∗
1
A[1:0]=
∗
0
0
1'
1
15
Source (general-purpose register)
Destination (16-bit device)
Bus operation
Big-endian
Figure 4.9 Byte Data Writing to a 16-bit Device
RD byte
15
Data bus
0
#WRL
1
1
#WRH
1
1
A0
1
0
A1
∗
∗
∗
No.
1
1'
Ignored
RD byte
Ignored
RD byte
31
0
A[1:0]=
∗
0
A[1:0]=
∗
1
0
1'
1
15
Bus operation
Sign or Zero extension
Destination (general-purpose register)
Source (16-bit device)
Little-endian
RD byte
15
Data bus
0
#WRL
1
1
#WRH
1
1
A0
0
1
A1
∗
∗
∗
No.
1
1'
Ignored
RD byte
Ignored
RD byte
31
0
A[1:0]=
∗
1
A[1:0]=
∗
0
0
1'
1
15
Bus operation
Sign or Zero extension
Destination (general-purpose register)
Source (16-bit device)
Big-endian
Figure 4.10 Byte Data Reading from a 16-bit Device
Data retained
15
Data bus
0
#WRL
0
0
0
0
#WRH
X
X
X
X
A0
0
1
0
1
A1
0
0
1
1
No.
1
2
3
4
2
3
4
Byte 0
Data retained
Byte 1
Data retained
Byte 2
Data retained
Byte 3
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=10
A[1:0]=00
A[1:0]=11
A[1:0]=01
8
0
1
4
8
8
8
0
0
0
Source (general-purpose register)
Destination (8-bit device)
3
2
Bus operation
(X: Not connected/Unused)
Little-endian
Byte 3
15
Data bus
0
#WRL
1
1
1
1
#WRH
0
0
0
0
A0
0
1
0
1
A1
0
0
1
1
No.
1
2
3
4
2
3
4
Data retained
Byte 2
Data retained
Byte 1
Data retained
Byte 0
Data retained
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=01
A[1:0]=11
A[1:0]=00
A[1:0]=10
8
0
4
1
8
8
8
0
0
0
Source (general-purpose register)
Destination (8-bit device)
2
3
Bus operation
Big-endian
Figure 4.11 Word Data Writing to an 8-bit Device
Ignored
15
Data bus
0
#WRL
1
1
1
1
#WRH
X
X
X
X
A0
0
1
0
1
A1
0
0
1
1
No.
1
2
3
4
2
3
4
Byte 0
Ignored
Byte 1
Ignored
Byte 2
Ignored
Byte 3
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=10
A[1:0]=00
A[1:0]=11
A[1:0]=01
8
0
1
4
8
8
8
0
0
0
3
2
Bus operation
(X: Not connected/Unused)
Destination (general-purpose register)
Source (8-bit device)
Little-endian
Byte 3
15
Data bus
0
#WRL
1
1
1
1
#WRH
1
1
1
1
A0
0
1
0
1
A1
0
0
1
1
No.
1
2
3
4
2
3
4
Ignored
Byte 2
Ignored
Byte 1
Ignored
Byte 0
Ignored
Byte 3
Byte 2
Byte 1
Byte 0
31
0
A[1:0]=01
A[1:0]=11
A[1:0]=00
A[1:0]=10
8
0
4
1
8
8
8
0
0
0
2
3
Bus operation
Destination (general-purpose register)
Source (8-bit device)
Big-endian
Figure 4.12 Word Data Reading from an 8-bit Device