AP160

Version 0.0

5

AMIC Technology, Inc.

SYMBOL

TYPE

DESCRIPTIONS

ALE/PROG

O/I

Address Latch Enable is an output pulse for latching the low byte of the address during

accesses to external memory. This pin is also the program pulse input (PROG) during

Programming on-chip OPT EPROM. In normal operation, ALE is emitted at a constant rate of

1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note,

however, that one ALE pulse is skipped during each access to external data memory. If

desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set,

ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled

high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution

mode.

PSEN

O

Program Store Enable is the read strobe to external program memory. When the AP160 is

executing code from external program memory, PSEN is activated twice each machine cycle,

except that two PSEN activations are skipped during each access to external data memory.

EA/Vpp

I

External Access Enable. EA must be strapped to GND in order to enable the device to fetch

code from external program memory locations starting at 0000H up to FFFFH. Note, however,

that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to

VCC for internal program executions. This pin also receives the 12-volt programming enable

voltage (VPP) during programming OTP EPROM.

XTAL1

I

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

O

Output from the inverting oscillator amplifier.