CF cards on classic machines (was Re: Another disk imaging project)

[Roger Merchberger]

Rumor has it that Jim Brain may have mentioned these words:
>Paul Koning wrote:
>
>>No... the classic PIO mode IDE registers are 8 bits wide, not 16.
>>Some devices may allow 16 bit access as an optimization, but 8 bit
>>accesses is all you need.
>>
>The IDE command registers are all 8-bits wide, but the Data register is 16 
>bits wide. You have to support a 16 bit transfer in order to get the data 
>from the sector buffer (256 16 bit transfers nets you 512 bytes of data, 
>the IDE std sector).  IN the newer 48 bit addressing mode, the LBA 
>registers grow from 8 bits to 16 bits as well.
>
>All the IDE code I've looked at does it this way.  I believe I have the 
>ATA r4 spec here that states that as well.
>But, if you've noted a way to switch IDE into 8-bit mode, let me know.

If you're looking for quick-n-dirty, you could always just ignore half of 
the capacity and send/receive 8 bits.... With 16 Meg flash cards, that 
might be less than optimal, but with the costs of 512M/1G cards where they 
are today, it is an option whilst still retaining a decently large amount 
of quick storage for an 8-bit machine, with a lot less hardware & coding to 
interface it.

This would preclude any sneakernet applications, however.

Just a [prolly dumb] thought,
Roger "Merch" Merchberger

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