Re: //c wonky internal drive

["Roger Johnstone" <rojaws@mac.com>]

----------
In article <3a2bf09e.3264957@news.videotron.ca>, 
mark.REMOVE.percival@videotron.ca (Mark Percival) wrote:


> On Sat, 02 Dec 2000, Eric Shepherd <sheppy@sheppyware.net> wrote:
>
>>in article is7i2t46o2lrca7gvmjgb2t48nsgqp961r@4ax.com, Spamshooting
>>Paranewsgrouper at spamgun@[127.0.0.1] wrote on 12/2/00 7:53 PM:
>>
>>> So one question: I'm sure there is a way to trick the computer into thinking
>>> the external drive (5.25) is the main drive. Anyone know how to do it?
>>
>>As I recall, the external 5.25" drive on the IIc is slot 7, so PR#7 should
>>boot it.
>
> I seem to recall the same but I think that this may have been true
> only in the original IIc.  I think that starting with the Unidisk 3.5
> enhanced motherboard is was moved back to slot 6, drive 2.
>
> Mark R. Percival
> An Apple II fanatic since 1979.
>
> Visit www.A2Central.com!

In the original IIc ROM version there were no ports mapped in to the slot 7
space. The external drive was still accessed as slot 6 drive 2, but Apple
put some code in the unused slot 7 space to allow booting from the external
drive. It worked with ProDOS, but with DOS 3.3 disks it would start to boot
from the external drive then after a second or two try to continue loading
from the internal drive. Presumably DOS 3.3 was hard coded to boot from
drive 1.

I can't remember if it was still there in the UniDisk 3.5 ROM revision, but
the next revision was for the IIc with the memory expansion connector. It
moved the mouse from slot 4 to slot 7 and put the RAM disk firmware in the
slot 4 space, leaving no where for the boot code.

--
Roger Johnstone, Invercargill, New Zealand

Apple II - Future Cop:LAPD - Warcraft II
http://homepages.ihug.co.nz/~rojaws
______________________________________________________________________

"First learn computer science and all the theory. Next develop a programming
style. Then forget all that and just hack."
George Carrette