Floppy controller questions

[Dwight K. Elvey]

Oops!
 Change all of the 20us to 16us. That is what I really
meant but had some brain rot.
Dwight

>From: "Dwight K. Elvey" <dwight.elvey at amd.com>
>
>>From: "Philip Pemberton" <philpem at dsl.pipex.com>
>>
>>In message <0ILP004N8EKHJER2 at vms040.mailsrvcs.net>
>>          Allison <ajp166 at bellatlantic.net> wrote:
>>
>>> Unless you use a drive that spins faster then the 500khz rate is fine.
>>
>>If it doesn't, I'll speedhack it to run at 300.
>>The only drive I've got that runs at 360 is a Y-E Data YD-380B. It completely
>>ignores the speed select pin, even though it's wired to "something" on the
>>PCB...
>>There are no visible jumpers anywhere, besides DS0 and DS1.
>>
>>> Yep, remember the worst case for "fast is 13us!  I'd plan for that.
>>> Also the slow rates will give you nominal 32us (27us worst case).
>>
>>Eek! Interrupt-mode it is then.
>
>---snip---
>
>Hi
> You might check the interrupt overhead. If you can't handle it
>in polled mode, it is unlikekly that interrupt mode will keep
>up. Although, the time between seeing the data available bit
>and transfering the data is 13us, at 500Khz the bytes will
>arrive at 20us rate. It changes what you need to do in which
           ^^^^
           16us
>order. Also, like I said in another post, if you know how
>fast your processor is running, you may not need to check
>the data available status every byte. Remember, they are
>comming at 20 us each. You need to know the uncertainty of
            ^^^^
            16us
>the first status( how long it takes to loop on the status). 
> You also don't need to worry too much about the first data
>available. Remember, the controller has to read across the
>header and gaps before it needs to transfer any data.
>Dwight
>
>
>
>