II CORE BLOCK: BCU (Bus Control Unit)

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[E:C]) / 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

0

0

16 KB

0

0

1

32 KB

0

1

0

64 KB

0

1

1

128 KB

1

0

0

256 KB

1

0

1

512 KB

1

1

0

1 MB

1

1

1

2 MB

At cold start, A10IR is set to "111" (2 MB). At hot start, A10IR retains its status before being initialized.

A10BW1–A10BW0: Burst read cycle wait control (D[A:9]) / Areas 10–9 set-up register (0x48126)

Set the number of wait cycles inserted during a burst read.

The values 0 to 3 written to the bits constitute the number of wait cycles inserted. The contents set here are applied to both areas 10 and 9. The wait cycles set by AxxWT are inserted in the first read cycle of burst ROM and in the burst ROM write cycle. For the burst ROM write cycle, the wait cycles set via the #WAIT pin can also be used. At cold start, A10BW is set to "0" (no wait cycle). At hot start, A10BW retains its status before being initialized.

A-1

B-II

BCU

S1C33L03 FUNCTION PART

EPSON

B-II-4-39