TMP91C824
91C824-79
(1) Memory
Start
Address
Registers
Figure 3.6.1 shows the Memory Start Address Registers. The Memory Start Address Registers
MSAR0 to MSAR3 set the start addresses for the CS0 to CS3 areas. Set the upper eight bits (A23 to
A16) of the start address in <S23: S16>. The lower 16 bits of the start address (A15 to A0) are
permanently set to 0. Accordingly, the start address can only be set in 64-Kbyte increments, starting
from 000000H. Figure 3.6.2 shows the relationship between the start address and the start address
register value.
Memory Start Address Registers (for areas CS0 to CS3)
7
6
5
4
3
2
1
0
bit Symbol
S23
S22
S21
S20
S19
S18
S17
S16
Read/Write
R/W
After reset
1
1
1
1
1
1
1
1
Function
Determines A23 to A16 of start address.
MSAR0
(00C8H)
MSAR1
(00CAH)
MSAR2
(00CCH)
MSAR3
(00CEH)
Sets start addresses for areas CS0 to CS3.
Figure 3.6.1 Memory Start Address Register
64K bytes
Address
000000H
FFFFFFH
000000H
・・・・・・・・・・・
00H
010000H
・・・・・・・・・・・
01H
020000H
・・・・・・・・・・・
02H
030000H
・・・・・・・・・・・
03H
040000H
・・・・・・・・・・・
04H
050000H
・・・・・・・・・・・
05H
060000H
・・・・・・・・・・・
06H
FF0000H
・・・・・・・・・・・
FFH
Start address
Value in start address register (MSAR0 to MSAR3)
to
to
Figure 3.6.2 Relationship between Start Address and Start Address Register value