82
User’s Manual U11969EJ3V0UM00
CHAPTER 4 BUS CONTROL FUNCTION
4.2 Bus Control Pins and Control Register
4.2.1 Bus control pins
The following pins are used for interfacing to external devices:
External Bus Interface Function
Corresponding Port (pins)
Address/data bus (AD0 to AD7)
Port 4 (P40 to P47)
Address/data bus (AD8 to AD15)
Port 5 (P50 to P57)
Address bus (A16 to A23)
Port 6 (P60 to P67)
Read/write control (LBEN, UBEN, R/W, DSTB, WRL, WRH, RD)
Port 9 (P90 to P93)
Address strobe (ASTB)
Port 9 (P94)
Bus hold control (HLDRQ, HLDAK)
Port 9 (P95, P96)
External wait control (WAIT)
WAIT
The bus interface function of each pin is enabled by the memory expansion mode register (MM). In ROM-less
mode, the bus interface function of each pin is unconditionally enabled by the MODE input (n = 0 to 2). For the details
of specifying an operation mode of the external bus interface, refer to 3.4.6 (1) Memory expansion mode register
(MM).
4.2.2 Control register
(1) System control register (SYC)
This register switches control signals for bus interface.
The system control register can be read/written in 8- or 1-bit units.
Bit Position
Bit Name
Function
1
BIC
Bus Interface Control
Changes bus interface control signal
0 : DSTB, R/W, UBEN, LBEN signal outputs
1 : RD, WRL, WRH, UBEN signal outputs
RD, WRL, WRH, and UBEN signals are output immediately after reset in ROM-less mode 2.
Address
FFFFF064H 00H
01H
(in single-chip mode 1, 2
and ROM-less mode 1)
(in ROM-less mode 2)
7
0
SYC
6
0
5
0
4
0
3
0
2
0
1
0
0
BIC
After reset
Содержание V854 UPD703006
Страница 2: ...2 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 22: ...22 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 80: ...80 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 134: ...134 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 156: ...156 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 294: ...294 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 320: ...320 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 324: ...324 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 336: ...336 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 376: ...376 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 382: ...382 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 394: ...394 User s Manual U11969EJ3V0UM00 MEMO ...
Страница 396: ...396 User s Manual U11969EJ3V0UM00 MEMO ...