[comp.sys.apple2] Need a little help or a few suggestions...

appleman@pro-truckstop.cts.com (The Sanitarium) (10/16/90)

I am currently running a //e system with one of apple's new HS SCSI cards. The
card is nice and all, but even with software that has been mentioned several
times (RGB.SCSIHACER, ET AL) I cannot get the card to recognise any more than
two partitions unless the card is resident in slot #5. Unless I am just being
a total oaf and am not running this software correctly, the problem seems to
be one of a hard coded limitation in the programmed roms on the card. If this
is the case, are there any of you hardware whizzes out there that can help me
find the location so I can burn a new EPROM or something? The real problem is
that Apple has apparently forgotten that most protected software on 5-1/4
media is expecting the controller card to be in slot# 6. Therefore, if I have
the 5-1/4 card where it runs properly (#6), I lose the HD as a startup device.
The truly odd thing is that I don't really know why Apple chose #5 over #7 for
the SCSI preferred slot anyway, since almost everyone I know has the HD
resident in slot# 7.

Second question os this: I have had my //e for a while and have accumulated
many more cards that I can possibly use in the 7 slots at any one time. I
would like to make (or buy if one is available...no sense in re-inventing the
wheel) a box of sorts that would have one hookup to one of the 50 pin slot
connectors inside the //e and branch that out to 3 or 4 50 pin connectors
inside the box. The problem I have is in the actual switching that would have
to take place between the slots that would be in the box. Is there just one or
two pins on the card that I can switch on/off that would render the card
invisible to the machine, or do I have to figure some complex switching device
that would activate all 50 pins at once? Also, once I figure out the switching
method, do I have to shut the system down to switch from one card to another,
or can I switch the cards while powered up?

Thanks in advance...

(You think I should have put a MAC slam in there to have insured a
response? :) )

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        [ My opinions are not my own. They're someone else's ]

toddpw@tybalt.caltech.edu (Todd P. Whitesel) (10/16/90)

First, the reason for the two drive limit is in prodos itself. Published
specs for prodos are such that only two drives may be associated with each
slot, period. Apple gets around this by mapping the next two into another
slot so that prodos thinks there are two drives in one slot and two in
another -- some programs still break but Apple documented it pretty well
so there haven't been too many problems.

I forget _why_ it only works in slot 5, but in any case SCSIPART will solve
things by manually mapping the extra partitions into slot 1 drives 1 and 2.

SCSIPART will soon be available for anonymous ftp, I will post an announcement
in a few days giving the details.

As for your 'extender box' idea, most cards are designed to apple's guidelines
and rely on only these signals as master enables:

pin	name
1	IOSEL
20	IOSTRB
39	M2SEL (only in the GS)
41	DEVSEL

so for a //e box you only need to switch 3 lines -- assuming the cards are
designed properly. In general, if it works in both the GS and the //e, then
it uses IOSEL, IOSTRB, and DEVSEL. The only card I know of that pays any
attention at all to M2SEL is the Video Overlay Card.

All the other pins (except DMA IN/OUT and INT IN/OUT, which you will want to
leave unconnected) are identical on all slots as far as you are concerned.

Todd Whitesel
toddpw @ tybalt.caltech.edu