Hi there,

I have a problem interfacing a dallas DS80C400 (based in a 8032 with external demultiplexed addressing ability) with a 1Mb Flash ROM (Spansion S29AL008D70BFI010), using 20 uC address lines in demultiplexed mode with memory in data byte mode. We have already prototyped a few boards doing the connections between uC and memory as maxim app note 3478 says (http://www.maxim-ic.com/appnotes.cfm/an_pk/3478 see table 3), this is connecting:

A0..A10 uC address lines to A0..A10 memory address lines
A11 uC address line to A-1 memory address line ???
A12..A19 uC address lines to A11..A18 memory address lines

We checked also an Spansion app note called "flash_to_sys_addr_bus" (http://www.spansion.com/applicati...n_a0_e.pdf ) that says the connections with a processors have to be in a different way that the maxim one mentioned above. What Spansion says is:

A0 uC address line to A-1 memory address line
A1..A19 addres lines to A0..A18 memory address lines

We are programming the flash ROM in system circuit, by the uC. We first program a Tiny400 firmware (v15 is stable for us), and then the slush (with some own instructions)

So we don't really understand well why the A11 micro address line has to be connected to A-1 memory address line, and specially we don't really know if the uC is internally doing something to correct that aparently wrong connection (seen from Spansion memory point of view) when it addresses the memory map, or instead if the addressing is being altered by that A-1 line and the memory areas used in any access are others than areas expected (although our code is working well)

Now we want the memories already programmed in factory, before PCB assembly, and doubts are comming to us:
Once we have generated the code memory file (.bin .hex or whichever) we are not sure the memory programmer will
program exactly the same bit patterns inside the memory (I mean, the whole 1 Mbyte) as the DS80C400 do it when the memory is programmed in the system by the micro.
I mean, the code is working well when programmed and read by the micro, but will work correctly if programmed by a EPROM programmer and later read by the micro? Do I have in some way to translate the code?

Has anyone any experience managing this kind of word/byte selectable memories and had similar problems?
Any ideas or comments wil be gratly apreciated

Regards