RE: Update IDEJD6
Date: 2008-04-15 07:57:31

Hallo Jim,

> But, I like Craig's idea in another context.  Use u0>h* to
> move to different virtual "heads" in the partition. 

1) The problem is that we HAVE to write 512 bytes when writing a sector.
So when writing a sector of 356 bytes, we first have to read the whole
512 bytes sector (but we save only the 256 bytes of the other sector)
and then write both sectors back to the disk. The problem is the memory
for the "hidden" sector. There are programs, database PRGs most of the
time, that eat up all the buffers, thus leaving us with no buffer to
temporary saving that extra sector. 
2) You cannot copy files from one "head" to the other "head" in a normal

Then I rather prefer a FS that knows about this extra sector and will
reserve memory for it as needed. And running the risk that some PRGs
find themself with less buffers then expected.

The above strengthes my opinion to add some extra RAM when using the
16-bits interface. Piggybacking another 2KB SRAM and, to keep it simple,
only using 1 KB of it, solves the problem. Someone able to add the IDE
interface should be capable of adding this SRAM as well IMHO. And with a
bit of luck I can program the FS so that it has at least two extra
buffers available.

> You could use u0>h1 to access a completely new set of 256
> partitions as a different drive, using the same drive number.

That's what I'm doing using the CP command, the same one as used in CMD
drives. @CP:5 for example swithes to partition 5.

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