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CONNECTING EXTERNAL DEVICES

7733 Group User’s Manual

12–5

: External area

00000016

Internal RAM

area

SFR area

Memory expansion mode

02000016

FFFFFF16

Internal RAM

area

SFR area

Microprocessor mode

00100016

00000016

FFFFFF16

00100016

00008016

Internal ROM

area (Note)

00008016

Note: This is applied when the memory allocation selection bits (bits 2 to 0 at address 63 16) = “0002.”

For details, refer to section “2.4 Memory allocation.”

12.1.1 External bus (A0 to A7, A8/D8 to A15/D15, and A16/D0 to A23/D7)

The address is output from pins A0 to A23 and specify the external area. Figure 12.1.2 shows the external

area. Pins A8 to A23 of the external address bus and pins D0 to D15 of the external data bus share the

same pins. When pin BYTE’s level, which is described later, is “L,” in other words, when the external data

bus is 16 bits wide, pins A8/D8 to A15/D15 and A16/D0 to A23/D7 perform address output and data input/

output with the time-sharing method. When pin BYTE’s level is “H,” in other words, when the external data

bus is 8 bits wide, pins A16/D0 to A23/D7 perform address output and data input/output with the time-sharing

method and pins A8 to A15 output the address.

Fig. 12.1.2 External area

12.1 Signals required for accessing external devices

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