Re: Using 20SC with //GS?

[marvinmiller@hotmail.com (Marvin Miller)]

Hi David;

Thank you very much for the comprehensive reply! As Greg mentioned in
a later post, I am buying his 6 meg RAM card that he used successfully
with his ROM 03 so I'm sure there won't be issues there as he used
this combo for a while (from the sounds of it).

After going through your post it seems that there are 'mass storage'
difficulties with the //gs, at least in the hard drive department.
This is unfortunate as I would have liked to have been able to store
ALL Apple // programs currently available for d/l from the archives
etc. (+/- 750 megs?) I thought that given modern storage capacity vs
older, smaller progs - there would be no problems.

It seems that the number of partitions is the limiting factor here.
Yuck! ;-)

Anyway, one of the reasons why I ask all these questions is so that I
can come up with a reasonable system design prior to purchasing the
peripheral cards. To that end I've come up with my dream machine and
it looks like this;

Rom 03 //GS (already bought)
(2) 5.25 drives (already bought)
(2) 3.5 drives (already bought)
ZipGS card (already bought)
6 Meg AE card (already bought)

Now, I plan to add a ramKeeper as well (got a line on one right now
and have to decide PDQ) and plug the 6 meg AE card into it and another
identical 6 meg AE card as soon as I find one. This would give a total
of 12 megs on the card + whatever's in the Rom 03 model. 

AE also made a 2 meg daughtercard for each of the 6 meg cards which
would bring the total installed memory to 16 megs if I could find
them. This is, as I understand it, the most you can put in the //GS.

Storage is the next equation. The problems you have noted about
partitions are new to me and very important. By your information I can
see that by having both types of floppys active I can only use around
288 megs of the hard drive. Can I get around this limit by using 3 or
4 more hard drives using 288 on each?

I'm going to need to think some more about this storage problem and a
way to get around it before asking more questions. The CD idea is a
great idea but the preference was to run 2 big drives and duplex (so
to speak) the data. 

So I guess the questions I have left (at the moment) are architectural
and experience related;

[1] Do you see anything wrong with the memory goals mentioned above?

[2] Can you run old A2 apps from the GS/OS (similar to a DOS window)?
If so, than at least I can have the maximum number of partitions
available to GS/OS?

[3] Is Apple's SCSI implementation the same as conventional SCSI? IE:
8/16 devices, Drive ID's etc

[4] Have you ever used a Zip drive on one of these puppies? I wonder
if that might be useful.

I guess the bottom line might be to wait until my //GS arrives and
than go from there based on actual observations. I was hoping to come
up with the 'ultimate' design first though....

Any more thoughts you might have on the storage side, or anything
else, would be great. 

Oh, and a question to all, how do you guys run your storage? Anyone
out there have around 750 megs of progs? How do you do it?

Best;
Marvin





On Thu, 2 Nov 2000 02:57:09 +1300, dempson@actrix.gen.nz (David
Empson) wrote:

>Marvin Miller <marvinmiller@hotmail.com> wrote:
>
>> What sounded simple is now getting complex! Perhaps I should give you
>> the complete scenario as it looks like there might be issues
>> looming....
>> 
>> I need a SCSI controller for my ROM 03 //gs.
>> I have two Quantum Fireball TM's (2.1gig) that are NT formatted that I
>> want to install into two cases (there seems to be no issue with the
>> cases, but maybe with the drives?)
>> 
>> In this //gs will be a 6 meg AE memory card and a ZipGS initally
>> running at 7Mhz and soon to pushed to at least 10Mhz.
>
>I can see an immediate problem here:
>
>Quantum Fireball drives will not work at all with a RamFast SCSI card.
>
>You must therefore use an Apple SCSI card.  The original Apple SCSI card
>is slow and severely limits the number of partitions under ProDOS-8 (a
>maximum of seven, spread over all mounted SCSI devices), so the Apple
>High-Speed SCSI card is your best option (it will give you at least
>seven partitions, and perhaps as many as eleven, depending on what cards
>are in the other slots and which internal ports are enabled).
>
>Using the Apple SCSI card raises another problem: if you have a memory
>expansion card larger than 4 MB, it cannot use DMA to access memory
>beyond the 4 MB point.  With some large cards, it is safe to leave DMA
>enabled, and you will only get slower performance with the "extra" RAM.
>With other cards, you will get memory corruption, because the DMA ends
>up going to the wrong area on the card, and the only option is to
>disable DMA on the SCSI card.  This causes a major performance hit.
>
>With some cards that support more than 4 MB, this problem comes up even
>if the card only has 4 MB (or less) installed.  It depends on how the
>card decodes memory addresses.
>
>In some cases you might be able to avoid problems by setting up a large
>enough /RAM5 volume to permanently reserve the memory beyond the 4 MB
>limit, i.e. at least 2 MB in the case of a 6 MB card.
>
>The RamFast is able to work around these issue with some but not all
>large memory expansion cards: it can do DMA right up to the 8 MB limit.
>
>
>In addition, the Applied Engineering GS RAM Plus is a very old card.  If
>it is the original version of this card (dating back to 1986 or '87), it
>might not work at all in a ROM 3 IIgs.  There may be a workaround by
>using a modified PAL/GAL, and/or there may have been a later revision of
>the card which is compatible with ROM 3.
>
>
>Any compatibility questions here could be answered if someone else out
>there has a ROM 3 IIgs with a 6 MB AE GS RAM Plus and an Apple
>High-Speed SCSI card with DMA enabled, and it is working.  (I have a ROM
>3 and Apple HS SCSI card, but I'm using a different memory expansion
>card, which is limited to 4 MB.)
>
>If it turns out that there is a compatibility problem, I'd suggest
>getting a different memory expansion card rather than disabling DMA on
>the SCSI card (though you could do that as an interim measure).
>
>I've found that a 4 MB card has been quite sufficient (in a ROM 3), and
>I have 800 KB set aside as a /RAM5 volume.  About the only time I ran
>out of memory was when I was trying out one of the fax programs, which
>seemed to permanently tie up rather a lot of RAM.
>
>
>Another problem you may encounter is that the Zip GS may perform poorly
>with large (over 4MB) memory expansion cards, though I've only seen one
>report of this, and it only affected some operations.
>
>> Given (2) 2.1 gig drives, will I be able to 'see' all that space under
>> ProDos?
>
>No.  The most you can possibly access under ProDOS-8 with an Apple
>High-Speed SCSI card would be 13 partitions, each 32 MB, for a total of
>416 MB.  This assumes you have no other storage devices in the slots,
>and both the internal SmartPort and Disk Port (slots 5 and 6) are
>disabled, i.e. no floppies.  This isn't a very useful combination.
>
>A more probable combination (slot 5 set to SmartPort, with one or two
>3.5" drives, or one 3.5" drive and /RAM5) would give you a maximum of 11
>partitions, or 352 MB.
>
>If you also enable the built-in 5.25" drive support (slot 6) you would
>be down to 9 partitions, or 288 MB.
>
>
>Under GS/OS, you are limited to 63 partitions over all hard drives, but
>even then you wouldn't be able to access all of a single drive if you
>stuck to ProDOS.  It is more usual to have a combination of ProDOS and
>HFS partitions.
>
>You are likely to have difficulty creating more than eight partitions on
>a single drive.  It is possible to create more than this on a large
>volume using Advanced Disk Utility (the GS/OS partitioning software) but
>it is rather fiddly.
>
>A CD-ROM drive with several multi-partition ProDOS CDs might be a better
>solution.  You could copy a program or partition to a hard drive if the
>program needed write access.
>