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· Hardware
#Memory Expansion
7 messages in this thread
I don't doubt that. What do they do? Segment the RAMs into 57.4K chunks?
<grin> The 4502A is the 256K version of the 4500, and I have an application
note on the 4500 that just about makes me drool.
no. what they do is provide no external control over when a refresh gets
done (ie, no way to synchronize a refresh with an empty bus cycle). they
simply provide select and read/write inputs, and give you a wait signal for
output. gag. –Scotty
The THCT4502A DOES provide an external REFREQ* input, meaning that you can
disable its internal refresh clock and generate your own refresh cycles when
you desire. I don't know how much it will speed up memory access, since when
the 68000 is doing a memory read, its generally for the prefetch queue
anyway. I think if you try to get much more complex about refresh cycles, you
are going to make this 48 pin chip pretty much useless anyway. Ah, well,
The THCT4502A DOES provide an external REFREQ* input, meaning that you can
disable its internal refresh clock and generate your own refresh cycles when
you desire. I don't know how much it will speed up memory access, since when
the 68000 is doing a memory read, its generally for the prefetch queue
anyway. I think if you try to get much more complex about refresh cycles, you
are going to make this 48 pin chip pretty much useless anyway. Ah, well,
You are right, but then again, the stuff that is needed in addition to the
controller looks to be minimal compared to the rat's nest we would have
without it.
You are right, but then again, the stuff that is needed in addition to the
controller looks to be minimal compared to the rat's nest we would have
without it.
no. what they do is provide no external control over when a refresh gets
done (ie, no way to synchronize a refresh with an empty bus cycle). they
simply provide select and read/write inputs, and give you a wait signal for
output. gag. –Scotty