7751 Group User’s Manual
2.1 Central processing unit
CENTRAL PROCESSING UNIT (CPU)
2–9
(6)
Bit 5: Data length flag (m)
It determines whether to use a data as a 16-bit unit or as an 8-bit unit. A data is treated as a 16-
bit unit when this flag is “0,” and as an 8-bit unit when it is “1.”
Use the SEM or SEP instruction to set this flag to “1,” and use the CLM or CLP instruction to clear
it to “0.” This flag is cleared to “0” at reset.
Note: When transferring data between registers which are different in bit length, the data is transferred
with the length of the destination register, but except for the TXA, TYA, TXB, TYB, and TXS
instructions. Refer to “7751 Series Software Manual” for details.
(7)
Bit 6: Overflow flag (V)
It is used when adding or subtracting with a word regarded as signed binary. When the data length
flag (m) is “0,” the overflow flag is set to “1” when the result of addition or subtraction exceeds the
range between –32768 and +32767, and cleared to “0” in all other cases. When the data length flag
(m) is “1,” the overflow flag is set to “1” when the result of addition or subtraction exceeds the range
between –128 and +127, and cleared to “0” in all other cases.
The overflow flag is also set to “1” when a result of division exceeds the register length to be stored
in the DIV or DIVS instruction, a division instruction with unsigned or signed; and when a result of
addition exceeds the range between –2147483648 and +2147483647 in the RMPA instruction, a
Repeat MultiPly and Accumulate instruction.
When the BVC or BVS instruction is executed, this flag’s contents determine whether the program
causes a branch or not.
Use the SEP instruction to set this flag to “1,” and use the CLV or CLP instruction to clear it to “0.”
Note: This flag is invalid in the decimal mode.
(8)
Bit 7: Negative flag (N)
It is set to “1” when a result of arithmetic operation or data transfer is negative. (Bit 15 of the result
is “1” when the data length flag (m) is “0,” or bit 7 of the result is “1” when the data length flag (m)
is “1.”) It is cleared to “0” in all other cases. When the BPL or BMI instruction is executed, this flag
determines whether the program causes a branch or not. Use the SEP instruction to set this flag to
“1,” and use the CLP instruction to clear it to “0.”
Note: This flag is invalid in the decimal mode.
(9)
Bits 10 to 8: Processor interrupt priority level (IPL)
These three bits can determine the processor interrupt priority level to one of levels 0 to 7. The
interrupt is enabled when the interrupt priority level of a required interrupt, which is set in each
interrupt control register, is higher than IPL. When an interrupt request is accepted, IPL is stored in
the stack area, and IPL is replaced by the interrupt priority level of the accepted interrupt request.
There are no instruction to directly set or clear the bits of IPL. IPL can be changed by storing the
new IPL into the stack area and updating the processor status register with the PUL or PLP instruction.
The contents of IPL is cleared to “000
2
” at reset.
Summary of Contents for 7700 FAMILY
Page 2: ...MITSUBISHI 16 BIT SINGLE CHIP MICROCOMPUTER 7700 FAMILY 7751 SERIES 7751 Group User s Manual...
Page 11: ...Table of Contents viii 7751 Group User s Manual MEMORANDUM...
Page 157: ...TIMER B 6 28 7751 Group User s Manual 6 5 Pulse period pulse width measurement mode MEMORANDUM...
Page 245: ...7751 Group User s Manual 8 36 A D CONVERTER Precautions when using A D converter MEMORANDUM...
Page 265: ...7751 Group User s Manual WAIT MODE 11 6 11 3 Precautions for Wait mode MEMORANDUM...
Page 289: ...CONNECTION WITH EXTERNAL DEVICES 12 4 Hold function 7751 Group User s Manual 12 24 MEMORANDUM...
Page 290: ...CHAPTER 13 RESET 13 1 Hardware reset 13 2 Software reset...
Page 302: ...CHAPTER 14 CLOCK GENERATING CIRCUIT 14 1 Oscillation circuit example 14 2 Clock...
Page 307: ...CLOCK GENERATING CIRCUIT 7751 Group User s Manual 14 6 14 2 Clock MEMORANDUM...
Page 360: ...CHAPTER 16 STANDARD CHARACTERISTICS 16 1 Standard characteristics...
Page 366: ...CHAPTER 17 APPLICATIONS 17 1 Memory expansion...
Page 405: ...APPLICATIONS 7751 Group User s Manual 17 40 17 1 Memory expansion MEMORANDUM...
Page 406: ...CHAPTER 18 PROM VERSION 18 1 EPROM mode 18 2 Usage precaution...
Page 417: ...7751 Group User s Manual PROM VERSION 18 12 18 2 Usage precaution MEMORANDUM...
Page 418: ...CHAPTER 19 FLASH MEMORY VERSION 19 1 Parallel input output mode 19 2 Serial input output mode...
Page 451: ...FLASH MEMORY VERSION 7751 Group User s Manual 19 34 19 2 Serial input output mode MEMORANDUM...
Page 484: ...APPENDIX 7751 Group User s Manual 20 33 Appendix 4 Package outlines 80D0...
Page 489: ...APPENDIX 7751 Group User s Manual 20 38 Appendix 6 Hexadecimal instruction code table...
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Page 492: ...APPENDIX 7751 Group User s Manual 20 41 Appendix 7 Machine instructions...
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Page 536: ...GLOSSARY...
Page 539: ...GLOSSARY 7751 Group User s Manual 4 MEMORANDUM...