MPD78C14 datasheet(90/373 Pages) NEC

90 / 373 page

CHAPTER 4

PORT FUNCTIONS

(2) Expansion mode

Port F input/output pins (PF7 to PF0) can be used as address outputs corresponding to the size of external

expansion memory, as shown in Table 4-2. This setting is performed by means of the memory mapping

Pins not used as address outputs are set to port mode.

Table 4-2. Operation of PF7 to PF0 (

µPD78C18/78C14/78C14A/78C12A/78C11A/78CP18/78CP14)

PF7

PF6

PF5

PF4

PF3

PF2

PF1

PF0

External Address Space

Port

Up to 256 bytes

Port

AB11

AB10

AB9

AB8

Up to 4K bytes

Port

AB13

AB12

AB11

AB10

AB9

AB8

Up to 16K bytes

AB15

AB14

AB13

AB12

AB11

AB10

AB9

AB8

Up to 31K/48K/56K/60K bytesNote

Note 31K (

µPD78C18), 48K (µPD78C14/78C14A), 56K (µPD78C12A), 60K (µPD78C11A). The operation of the

µPD78CP18 and 78CP14 differ depending on the setting of bits MM5 to MM7 of the memory mapping

µPD78C17/78C10A

These pins function as address outputs corresponding to the size of externally installed memory according to the

MODE0 and MODE1 pin settings.

Pins which are not used as address outputs can be used as general-purpose input/output port pins which have

the same port functions as port A, with input/output setting performed by the mode F register.

Table 4-3. Operation of PF7 to PF0 (

µPD78C17/78C10A)

MODE1

MODE0

PF7

PF6

PF5

PF4

PF3

PF2

PF1

PF0

External Address Space

Port

AB11 AB10

AB9

AB8

4K bytes

Port

AB13 AB12 AB11 AB10

AB9

AB8

16K bytes

Setting prohibited

AB15 AB14 AB13 AB12 AB11 AB10

AB9

AB8

63K/64K bytesNote

Note 63K (

µPD78C17), 64K (µPD78C10A)

Cautions 1. Pins not used as address bus pins output the internal address bus status in all machine cycles.

When the address changes, undefined data is output.

2. Emulation cannot be performed by an emulator for a program which varies the port F

operating mode dynamically. Therefore, once the mode has been set, it should not be changed

to a different mode.

When the 63K/64K-byte mode is used with the

µPD78C17/78C10A, instructions which output data to port D or

port F should not be executed; if such an instruction is executed, the WR signal will be output.

MPD78C14 Datasheet(PDF) 90 Page - NEC

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