hzink@pro-nucleus.UUCP (Harry Zink) (05/10/89)
Here's my problem, and hopefully someone will have a solution (of some kind).
As you know, if you run a SCSI drive on the apple II series, Prodos can
address two devices per slot. This applies to all slots, except slot 5,
whehre you can have 4 SCSI devices (2 of them shadowed in slot 2). So far so
good. Now let's examine the intelligence behind implementing this scheme.
Obviously, slot 6 is always reserved for floppy drives, slot 5 is a normal
disk drive slot, but where do most people tend to put their hard drives? Slot
7, the logical choice, of course. Now, which is the slot that apple chose to
give the magic extensions of 4 devices to? Slot 5, of course. This is all
nice and dandy, except that this way, those of us with 3.5 drives, are forced
to put them in slot 7, thereby loosing the option of booting directly from the
hard drive (except those of us with a GS). Now you have to turn off the
machine, hit reset, and type PR#5. Not really a big deal, but it does show
the extreme lack of intelligence of those who even decided to give slot 5 the
'magic' capabilities, ignoring slot 7 conveniently (of course, since that is
the one that most users would need).
Anyway, enough gripes from me here, my question pertains to a possible
solution. I assume that there is special code in Prodos that decides that
slot 5 has the special abilities, and all other slots are normal. I also
assume that the selection of slot 5 was more or less arbitrary (If I'm wrong
on any of these assumptions, feel free to jump in any time). Now, is there
some way to patch/modify Prodos to give slot 7 the abilities it should have
had in the first place, i.e. the ability to address up to 4 SCSI devices?
Has anyone experimented with some modifications that would allow this, or
successfully implemmented them? If so, please share this information with the
rest of us (most of all ME), so we can run our hard drives from slot 7 once
again.
profound thanks to those answering this.
Hzink@pro-nucleus
+
hzink@pro-nucleus
crash!pnet01!pro-nucleus!hzink : UUCP
+mattd@Apple.COM (Matt Deatherage) (05/11/89)
In article <8905100737.AA12945@crash.cts.com> pnet01!pro-sol!pro-nucleus!hzink@nosc.mil writes: >Here's my problem, and hopefully someone will have a solution (of some kind). > >As you know, if you run a SCSI drive on the apple II series, Prodos can >address two devices per slot. This applies to all slots, except slot 5, >whehre you can have 4 SCSI devices (2 of them shadowed in slot 2). So far so >good. Now let's examine the intelligence behind implementing this scheme. > >Obviously, slot 6 is always reserved for floppy drives, slot 5 is a normal > [attempted justification for this deleted] >Anyway, enough gripes from me here, my question pertains to a possible >solution. I assume that there is special code in Prodos that decides that >slot 5 has the special abilities, and all other slots are normal. I also >assume that the selection of slot 5 was more or less arbitrary (If I'm wrong >on any of these assumptions, feel free to jump in any time). Now, is there >some way to patch/modify Prodos to give slot 7 the abilities it should have >had in the first place, i.e. the ability to address up to 4 SCSI devices? > >Has anyone experimented with some modifications that would allow this, or >successfully implemmented them? If so, please share this information with the >rest of us (most of all ME), so we can run our hard drives from slot 7 once >again. > >profound thanks to those answering this. > > hzink@pro-nucleus > crash!pnet01!pro-nucleus!hzink : UUCP > + The justification for this is pure, and simple, and even close to logical. At boot time, ProDOS 8 looks at slot 5 and looks for a SmartPort firmware interface there. If it finds it and it has more than two devices connected to it, the third and fourth devices are shadowed to slot 2. This was done so that more than two devices (3.5" drives and RAM disks) could be used with the IIgs SmartPort in port 5. It just so happens that the Rev. C SCSI card was later designed such that it could also handle being shadowed to slot 2 if placed in slot 5. It is no massive "hard disk usage" strategy; it's simply a side effect of how ProDOS 8 was modified to work on the IIgs (without this, any RAM disk would mean a second 3.5" drive would be unusable). ----------------------------------------------------------------------------- Matt Deatherage, Apple Computer, Inc. | "The opinions expressed in this tome Send PERSONAL mail ONLY (please) to: | should not be construed to imply that AppleLink PE: Matt DTS GEnie: AIIDTS | Apple Computer, Inc., or any of its CompuServe: 76703,3030 | subsidiaries, in whole or in part, Usenet: mattd@apple.com | have any opinion on any subject." UUCP: (other stuff)!ames!apple!mattd | "So there." -----------------------------------------------------------------------------