Hi,

A few questions that baffle me.. I'm a software engineer so the hardware
side is a bit confusing for me!!

Our design uses an 89c52 with 128k external flash and some external ram.

The flash uses A0-A15 (p0 & p2) + an A16 line fed from P1.0 / also D0-D7.
The A16 line being separate I guess means that I can effectively split the flash memory into 2 blocks if required..

The ram uses A0-A12 / also D0-D7 (via a latch (74HCT373)).

I've read in the 8051 tutorial that when using external flash/ram I cannot use port0 or port2 as output ports - is this true?

We also have a 12bit DAC (AD7542) (latched) and another latch for external lines connected to port0.

There are AND gates to each latch taking input from ALE off the 8952 and port1 pins.

I need to output nibbles to P0 to program the DAC (setting the Operation bits as well). Can this be done as I don't understand when ALE is enabled..

Does all this sound like it will work?

Kev