W83977EG-AW Datasheet, PDF (88/142 Pages) Nuvotem Talema – These products are not designed for use in life support appliances

W83977EF-AW/W83977EG-AW
CR26 (Default 0b0s000000)
Bit 7: SEL4FDD
= 0 Select two FDD mode.
= 1 Select four FDD mode.
Bit 6: HEFRAS
These two bits define how to enable Configuration mode. The corresponding power-on
setting pin is NRTSA (pin 43).
HEFRAS Address and Value
= 0 Write 87h to the location 3F0h twice.
= 1 Write 87h to the location 370h twice.
Bit 5: LOCKREG
= 0 Enable R/W Configuration Registers.
= 1 Disable R/W Configuration Registers.
Bit 4: Reserved.
Bit 3: DSFDLGRQ
= 0 Enable FDC legacy mode on IRQ and DRQ selection, then DO register bit 3 is effective
on selecting IRQ
= 1 Disable FDC legacy mode on IRQ and DRQ selection, then DO register bit 3 is not
effective on selecting IRQ
Bit 2: DSPRLGRQ
= 0 Enable PRT legacy mode on IRQ and DRQ selection, then DCR bit 4 is effective on
selecting IRQ
= 1 Disable PRT legacy mode on IRQ and DRQ selection, then DCR bit 4 is not effective
on selecting IRQ
Bit 1: DSUALGRQ
= 0 Enable UART A legacy mode IRQ selecting, then MCR bit 3 is effective on selecting
IRQ
= 1 Disable UART A legacy mode IRQ selecting, then MCR bit 3 is not effective on
selecting IRQ
Bit 0: DSUBLGRQ
= 0 Enable UART B legacy mode IRQ selecting, then MCR bit 3 is effective on selecting
IRQ
= 1 Disable UART B legacy mode IRQ selecting, then MCR bit 3 is not effective on
selecting IRQ
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