>I found the general connection of external parallel memory in the
>datasheets of the PIC17C75X. There is a (74HC)138 shown as the address
>decoder, but not explained.

You would use that to access the upper 64K banks of the 128K chip.

>My idea is that I connect the 16 address lines of both memory chips in
>parallel to the 74373s. The 2 x 8bit data lines are - of cause -
>formed together to a 16 bit bus.

Right.

>Is there any mistake in my idea?

If you don't need to field-reprogram, go with standard EPROMs.

>Can I run or do I HAVE TO run the PIC in microprocessor mode then ? Your
>idea of a setup program in the internal memory is good. Lets presume this
>for the question. Or: What happens when I use the external memory without
>GAL and I use additionaly internal memory ?

GAL is only to provide customizable bank switching.

>Can I have a look on the bios code to have a hint for my application ?
>(in case of copyrights - better send it directly to me:
>A.Dante@City.ac.uk)

Can't provide it - company proprietary, and not complete.

Andy

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Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA
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