Re: Apple File Exchange

[munz@wordperfect.com (Mark Munz)]

In article <ddoms-1304950522280001@ddoms.tyrell.net>, ddoms@tyrell.net
(Dennis Doms) wrote:

> In article <gburges-0804950742210001@dyn1-059.cc.umanitoba.ca>,
> gburges@cc.umanitoba.ca wrote:
> 
> > My Macintosh Centris 610 (sys 7.5) seems to have no trouble recognizing
> > the disk as some kind of Prodos II (is there a Prodos II?), but I'm
> > wondering if perhaps this doesn't work because this is some kind of newer
> > Appleworks that made these files.
> 
> It might be the version of AppleWorks, but...
> 
> When you say the disk is identified as "ProDOS II", I suspect that it's a
> "disk mounter" that's detecting the disk is Apple II ProDOS format and is
> placing it directly on the desktop. That makes it appear to be a "native"
> disk to the Mac, and so Apple File Exchange won't try to establish ProDOS
> to Mac translation protocols.

The issue at hand is that Apple File Exchange and PC Exchange (as well as
the Prodos Init) process prodos typing differently.

Under AFE, the standard approach was to use creator: 'pdos'. The type was
then and ascii representation of the two char type (in hex) followed by
two spaces. To obtain the Auxtype, you have to open the file's resource
fork, and look at the first two bytes. They are the auxtype (in the Mac's
hi-byte order).

Prodos: Type = $1A, AuxType = $2000
AFE   : '1A  ' , pdos resource contains 2000xxxxx(plus other unknown data)

The new PC Exchange uses a different approach (sometimes). It still uses
the 'pdos' creator, but now except for a few cases uses the following
scheme to store type and auxtype. The Mac type is stored as char 'p',
followed by the hex byte (indicating type), followed by the two hex bytes
(indicating auxtype) in hi-byte order.

hex numbers in parens mean actual hex value is stored.

Prodos    : Type = $1A, AuxType = $2000
PCExchange: 'p(1A)(20)(00)'

Of course, if you are a Mac program that needs to read Prodos, you need to
understand both.

Mark Munz