
II CORE BLOCK: BCU (Bus Control Unit)
B-II-4-40
EPSON
S1C33T01 FUNCTION PART
A18WT2–A18WT0: Areas 18–17 wait control (D[A:8]) / Areas 18–15 set-up register (0x48120)
A16WT2–A16WT0: Areas 16–15 wait control (D[2:0]) / Areas 18–15 set-up register (0x48120)
A14WT2–A14WT0: Areas 14–13 wait control (D[2:0]) / Areas 14–13 set-up register (0x48122)
A12WT2–A12WT0: Areas 12–11 wait control (D[2:0]) / Areas 12–11 set-up register (0x48124)
A10WT2–A10WT0: Areas 10–9 wait control (D[2:0]) / Areas 10–9 set-up register (0x48126)
A8WT2–A8WT0:
Areas 8–7 wait control (D[2:0]) / Areas 8–7 set-up register (0x48128)
A6WT2–A6WT0:
Area 6 wait control (D[A:8]) / Areas 6–4 set-up register (0x4812A)
A5WT2–A5WT0:
Areas 5–4 wait control (D[2:0]) / Areas 6–4 set-up register (0x4812A)
Set the number of wait cycles to be inserted when accessing an SRAM device.
The values 0 through 7 written to the control bits equal the number of wait cycles inserted.
Note that the write cycle consists of a minimum of two cycles, so that a writing 0 or 1 is invalid.
When an SRAM device is connected, wait cycles derived via the #WAIT pin can also be inserted. In this case too, the
wait cycles set by AxxWT are valid.
The DRAM read/write cycles do not have wait cycles inserted that are set by AxxWT or derived from the #WAIT pin.
The burst read cycle of a burst ROM (except for the first access) also does not have any wait cycle inserted. The first
read cycle of a burst ROM and the write cycle to the burst ROM area have wait cycles inserted that are set by
AxxWT . Wait cycles derived from the #WAIT pin also can be inserted in the cycle for writing to the burst ROM
area.
At cold start, these bits are set to "111" (7 cycles). At hot start, the bits retain their status before being initialized.
A14DRA: Area 14 DRAM selection (D8) / Areas 14–13 set-up register (0x48122)
A13DRA: Area 13 DRAM selection (D7) / Areas 14–13 set-up register (0x48122)
A8DRA: Area 8 DRAM selection (D8) / Areas 8–7 set-up register (0x48128)
A7DRA: Area 7 DRAM selection (D7) / Areas 8–7 set-up register (0x48128)
Select the DRAM direct interface.
Write "1": DRAM is used
Write "0": DRAM is not used
Read: Valid
When DRAM is used by connecting it directly to the BCU, write "1" to this bit. The ordinary SRAM interface is
selected by writing "0" to the control bit.
The areas to which DRAM can be connected are areas 8 and 7 when the CEFUNC = "0",or areas 14 and 13 when the
bit = "1".
At cold start, these bits are set to "0" (DRAM not used). At hot start, the bits retain their status before being
initialized.
A10IR2–A10IR0: Area 10 internal ROM size selection (D[D:B]) / Areas 10–9 set-up register (0x48126)
Select an area 10 internal/emulation memory size.
Table 4.25
Area 10 Internal ROM Size
A10IR2
A10IR1
A10IR0
ROM size
0
16KB
0
1
32KB
0
1
0
64KB
0
1
128KB
1
0
256KB
1
0
1
512KB
11
0
1MB
11
1
2MB
At cold start, A10IR is set to "111" (2MB). At hot start, A10IR retains its status before being initialized.