MB91F155A Datasheet, PDF (24/105 Pages) Fujitsu Component Limited. – 32-bit Proprietary Microcontrollers

MB91F155A/MB91155/MB91154
s SETTING MODE
1. Mode Pins
As shown in Table 1 three pins, MD2, 1, and 0 are used to indicate an operation.
Table 1 Mode pins and set modes
Mode pin
MD2 MD1 MD0
Mode name
Reset vector
access area
External data
bus width
0
0
0 External vector mode 0
0
0
1 External vector mode 1
External
External
8 bits
16 bits
External ROM bus mode
0
1
0 External vector mode 2
External
32 bits
Not available on this
product type
0
1
1 External vector mode
Internal
(Mode register) Single-chip mode
1 



Not available
2. Mode Data
The data which the CPU writes to “0000 07FFH” after reset is called mode data.
It is the mode register (MODR) that exists at “0000 07FFH.” Once a mode is set in this register, operations will
take place in that mode. The mode register can be written only once after reset.
The mode specified in the register is enabled immediately after it is written.
MODR
Initial value Access
Address : 0000 07FFH _M1
M0
∗
∗
∗
∗
∗
∗
XXXXXXXX W
W : Write only, X : Undefined
Bus mode setting bits
[bits 7 and 6] : M1, M0
These are bus mode setting bits. Specify the bus mode to be set to after writing to the mode register.
M1
M0
Function
Remarks
0
0
Single-chip mode
0
1
Internal ROM-external bus mode
1
0
External ROM-external bus mode
1
1

Setting not allowed
[bits 5 to 0] : ∗
These bits are reserved for the system.
“0” should be written to these bits at all times.
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