Re: cbm 1541 drive reading AppleIIe 5.25" disks?

[user580@EDVZBB2.BEN-FH.TUWIEN.AC.AT]

>Date:          5 Jun 93 00:59:25 GMT
>From:          nntp.telebit.com!news@uunet.uu.net  (Eric Smith)
>Organization:  Telebit Corporation
>Subject:       Re: cbm 1541 drive reading AppleIIe 5.25" disks?
>To:            info-apple@apple.com
>
On 5 Jun 93 00:59:25 GMT nntp.telebit.com!news@uunet.uu.net  (Eric Smith) 
wrote
>>>On 4 Jun 93 06:50:42 GMT, phillips@swanee.ee.uwa.edu.au (Christopher 
>Phillips) said:
>> Now, both
>> the apple II drive and the 1541 drive both use gcr, so
>> this should be really easy to write, if one could get hold
>> of the specs for apple II 5.25"s.
>
>No such luck.  GCR isn't a specific code, it is a whole family of codes.
>The Commodore disk hardware is much different than the Disk II, and I don't
>think there is any way that either can read the other's disks.

I wish to make three comments:

1) The format which is used by the C64 is defenitely different from the one
used by Disk II: The 1541 has a variable track length, that means the inner 
tracks contain less sectors than the outer. Disk II uses constant frequences 
- the time between two bits is constant, therefore each track has the same
number of sectors - 16.

2) In order to communicate via floppy you could try to adjust your 
RWTS-routine (Read-Write-Track-Sector, its the 'core' of DOS 3.3 where the 
basic read and write operations take place). But that could work only if you 
manage to adjust the positioning of the rw-head , for each track is 
seperated by only two stepper-steps form it's neighbour track. Good 
documentation of the 1541-format would be necessary ,too :-(

3) If you have a 1541-drive, you could try to custom it to the Apple ][: The  
protocol is basically IEEE, though the connector is not standart. 
Documentation may be available by C64-specialists (maybe the C64 and 1541 
handbooks will do, they contain a good deal of documentation)

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