Re: [avr-gcc-list] Off topic question - 3 1/2 PC Floppy drive

[JChavez]

I really appreciate your help however I still want to use
the floppy drive+ 3 1/2 floppy so based on what I understand
I should use an ATmega + enough RAM  to read a sector wich is 512 bytes length.
Besides I would like to find out  the standard for how to perform basic floppy
operations such as read, write or move the head using
the signals on the 34-pin connector. Does anyone know of a
white paper or specification of some kind detailing this
in the form of timing diagrams etc.?

Javier.







Iztok Zupet <address@hidden>@avr1.org con fecha 29/06/2002 12:22:43

Por favor, responda a address@hidden

Enviado por:   address@hidden


Destinatarios: Marek Michalkiewicz <address@hidden>,
        address@hidden
CC:     address@hidden
Asunto: Re: [avr-gcc-list] Off topic question - 3 1/2 PC Floppy drive


Hi:
 I don't think that the DMA for AVR is the crucial problem here. Old 4Mhz
Zilogs used to work with floppy without DMA, so it should be possible for
an
8Mhz AVR (which should be in fact 8 times faster then 4Mhz Zilog).

 The fact is that nowadays it's very difficult to obtain a floppy disk
controller chip, especially such which doesn't require a DMA interface. All
are namely integrated into bigger devices. So unless You have a free access
to a chip museum, better take Marek's advice.

Regards
iz


On Saturday 29 June 2002 15:09, Marek Michalkiewicz wrote:
> > I need to read data from a 1.44 MB floppy drive using an AT90S8535.
> > Is it posible? If so please send some info I mean any help would be
> > appreciated.
>
> You would need a floppy controller chip, and these are quite hard to
> program, especially as AVR has no DMA controller, so you have to read
> the data quickly or it will be lost, and the 8535 has no external
> address/data bus, and emulating that in software is slow...
>
> Some alternatives:
>
>  - IDE floppy drive: not as common and may be expensive.
>  - CompactFlash card: reasonably easy to connect (like a normal IDE hard
>    disk, 8-bit data bus is sufficient) and program (no hard real time
>    requirements), cheap USB-CF and PCMCIA-CF adapters are available, so
>    you can access the card on a desktop/notebook PC.
>
> Besides, floppies are so unreliable...  Use it a few times, and it
> starts developing bad sectors.  So, if you don't absolutely require
> floppy disks (just some small removable media), I'd suggest to go
> for CompactFlash instead.
>
> Marek
>
> avr-gcc-list at http://avr1.org


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