W78E54
Flash
No function in this mode.
EA/VPP
MODE
DESCRIPTION
EA External Access, Input, active low.
Normal
,
This pin forces the processor to execute a program from the external ROM. When the
internal flash EEPROM is accessed as in the W78C54, this pin should be kept high.
Flash
VPP, Program Power supply pin, Input.
This pin accepts the high voltage (12V) needed for programming the flash EEPROM.
RST
MODE
DESCRIPTION
Normal
RST, Reset, Input, active high.
This pin resets the processor. It must be kept high for at least two machine cycles in
order to be recognized by the processor.
Flash
Flash mode configuration pin, Input, active high.
RST is used to configure the flash operations. For details, see Flash Operations.
ALE
MODE
DESCRIPTION
Normal
Address Latch Enable, Output, active high.
ALE,
ALE is used to enable the address latch that separates the address from the data on
Port 0. ALE runs at 1/6th of the oscillator frequency. A single ALE pulse is skipped
during external data memory accesses. ALE goes to a high impedance state with a
weak pull-up during reset state.
Flash
Flash mode configuration pin, Input, active low.
ALE is used to configure the flash operations. For details, see Flash Operations.
PSEN
MODE
DESCRIPTION
Normal
PSEN Program Store Enable, Output, active low.
,
enables the external ROM onto the Port 0 address/data bus during fetch and
This pin
MOVC operations. PSEN goes to a high impedance state with a weak pull-up during
reset state
Flash
Flash mode configuration pin, Input, active high.
PSEN is used to configure the flash operations. For details, see Flash Operations.
XTAL1
MODE
DESCRIPTION
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WINBOND [ WINBOND ]
