16 MB REU clone

From: Marko Mäkelä (msmakela_at_cc.hut.fi)
Date: 2001-08-21 10:11:23


> Sounds very good. I do ask for one thing, if it's not too much trouble;
> Create a dipswitch arrangement where the user can select from 1, 2, 4, 8 or
> 16Mb out of the 16Mb cartridge 'REU'.

Hmm, why would you need that?  The high-order bits of the REU bank
selection register are normally unassigned, and the 2 MB REU hack is
implemented in such a way that the added bank selection bits cannot be
read by the processor.  All memory in the REU sits behind the controller,
and it can only be accessed by telling the controller to copy data
between the C64 and the expansion memory.

On the other hand, I don't know how the CMD RAMLink works, since I have
never seen the device or its schematic diagram.


> > I've verified that there exist 8 bits wide 16-megabyte SDRAM chips.
> I hope you're not talking about the 30 pin version.

No, but the MT48LC16M8A2, a 54-pin chip by Micron

Can you get this chip cheaply?  I haven't read the data sheet yet, so I
don't know how hard it is to interface this chip.  The address lines are
multiplexed with RAS and CAS signals, just like in the older DRAM chips.


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