APPLICATIONS
7751 Group User’s Manual
17–2
17.1 Memory expansion
17.1 Memory expansion
This section shows examples for memory and I/O expansion. Refer to “Chapter 12. CONNECTION WITH
EXTERNAL DEVICES” for details about the functions and operation of used pins when expanding a memory
or I/O. Refer to “Chapter 15. ELECTRICAL CHARACTERISTICS” for timing requirements of the microcomputer.
Application shown here are just examples. The user shall modify them according to the actual application
and test them.
17.1.1 Memory expansion model
Memory expansion to the external is possible in the memory expansion mode or the microprocessor mode.
The level of the external data bus width select signal makes it possible to select the four memory expansion
models shown in Table 17.1.1.
(1)
Minimum model
This is an expansion model of which external data bus width is 8 bits and accessible area is
expanded up to 64 Kbytes. It is unnecessary to connect the address latch externally. This is an
expansion model which is suited to having priority the cost when connecting the memory of which
external data bus width is 8 bits.
(2)
Medium model A
This is an expansion model of which external data bus width is 8 bits and accessible area is
expanded up to 16 Mbytes. In this expansion model, the high-order 8 bits of the external address bus
(A
23
to A
16
) are multiplexed with the external data bus. Therefore, an n-bit (n
≤
8) address latch is
required for latching address (n bits of A
23
to A
16
).
(3)
Medium model B
This is an expansion model of which external data bus width is 16 bits and accessible area is
expanded up to 64 Kbytes. This expansion model is used when having priority the rate performance.
In this expansion model, the middle-order 8 bits of the external address bus (A
15
to A
8
) are multiplexed
with the external data bus. Therefore, an 8-bit address latch is required for latching address (A
15
to
A
8
).
(4)
Maximum model
This is an expansion model of which external data bus width is 16 bits and accessible area is
expanded up to 16 Mbytes. In this expansion model, the high- and middle-order 16 bits of the
external address bus (A
23
to A
8
) are multiplexed with the external data bus. Therefore, an 8-bit
address latch for latching A
15
to A
8
and an n-bit (n
≤
8) address latch for latching n bits of A
23
to A
16
are required.
Содержание 7700 FAMILY
Страница 2: ...MITSUBISHI 16 BIT SINGLE CHIP MICROCOMPUTER 7700 FAMILY 7751 SERIES 7751 Group User s Manual...
Страница 11: ...Table of Contents viii 7751 Group User s Manual MEMORANDUM...
Страница 12: ...CHAPTER 1 DESCRIPTION 1 1 Performance overview 1 2 Pin configuration 1 3 Pin description 1 4 Block diagram...
Страница 48: ...CHAPTER 3 INPUT OUTPUT PINS 3 1 Programmable I O ports 3 2 I O pins of internal peripheral devices...
Страница 157: ...TIMER B 6 28 7751 Group User s Manual 6 5 Pulse period pulse width measurement mode MEMORANDUM...
Страница 245: ...7751 Group User s Manual 8 36 A D CONVERTER Precautions when using A D converter MEMORANDUM...
Страница 246: ...CHAPTER 9 WATCHDOG TIMER 9 1 Block description 9 2 Operation description 9 3 Precautions when using watchdog timer...
Страница 254: ...CHAPTER 10 STOP MODE 10 1 Clock generating circuit 10 2 Operation description 10 3 Precautions for Stop mode...
Страница 260: ...CHAPTER 11 WAIT MODE 11 1 Clock generating circuit 11 2 Operation description 11 3 Precautions for Wait mode...
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Страница 289: ...CONNECTION WITH EXTERNAL DEVICES 12 4 Hold function 7751 Group User s Manual 12 24 MEMORANDUM...
Страница 290: ...CHAPTER 13 RESET 13 1 Hardware reset 13 2 Software reset...
Страница 302: ...CHAPTER 14 CLOCK GENERATING CIRCUIT 14 1 Oscillation circuit example 14 2 Clock...
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Страница 359: ...ELECTRICAL CHARACTERISTICS 7751 Group User s Manual 15 52 MEMORANDUM 15 15 Testing circuit for ports P0 to P8 1 and E...
Страница 360: ...CHAPTER 16 STANDARD CHARACTERISTICS 16 1 Standard characteristics...
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Страница 366: ...CHAPTER 17 APPLICATIONS 17 1 Memory expansion...
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Страница 406: ...CHAPTER 18 PROM VERSION 18 1 EPROM mode 18 2 Usage precaution...
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Страница 418: ...CHAPTER 19 FLASH MEMORY VERSION 19 1 Parallel input output mode 19 2 Serial input output mode...
Страница 451: ...FLASH MEMORY VERSION 7751 Group User s Manual 19 34 19 2 Serial input output mode MEMORANDUM...
Страница 483: ...APPENDIX 7751 Group User s Manual 20 32 Appendix 4 Package outlines Appendix 4 Package outlines 80P6N A...
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Страница 489: ...APPENDIX 7751 Group User s Manual 20 38 Appendix 6 Hexadecimal instruction code table...
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Страница 536: ...GLOSSARY...
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