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I was in workshop of microchip. They told me to use new ROMless
PIC18F series with external synchronous memory interface but
I don't know the exact product name.
I've tried to do a such thing with a COP8 (National).
I get a chip from an old memory for 8086 (1bit * 1Mbit).
The problem is the refresh (obviously ... )
I would to use timer of COP8 to refresh DRAM with no µC overhead. I think it's possible but I have not tried that.
In fact, I begin with an IT that refresh some column of DRAM (2 or 3 for example). The overhead is minimum in this case.
It seems to work very good. In fact I can refresh the DRAM 10 time slower than nominal rate and it work ...
It's a bit strange ...
Another point is that it is a 1bit memory and the column and line adresses are multiplexed. So to put or get one byte, there are a lot of cycles ...
But I don't do a lot more, I have used that for getting CD-TEXT from a CD (and it work I get 1ko of text -- the same amount of data that the eniere COP8 contain) ... but the CD-ROM Player (Sony) died very few time after that ...
And I replaced it with another CD-ROM Player, but it can't retrieve CD-TEXT, so I have don't go further.
hi after looking at the code above
i realise that with little work
it becomes a good inc file module to acces dram via all platroms of pic
using just a simple couple of buffers etc some logic too do control
then you can also bank quite a lot within the pic
and page it as fresh routines via bootblock system
and nvram
i think it will work with or without eeprom on board but eeprom avalible restricts the addresses you have
choosing some extranious logic en pin etc can eleviate the address range issues
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