Re: ProDOS, IIgs and large RAM disks.

[Dennis Jenkins <dennis@usb.com>]

Ok.  It all works now.  The critical issue was doing a warm boot and not
a power off/on after changing the control panel settings.  Also, A piece
of third party software (zlink) errantly displays "/RAM" twice (the
first time one tabs through) in it's quit handler.  That is what led me
to believe that I had two /RAM volumes.

I never actually called the "online" mli to see what it said, I just
assumed that zlink was doing that.  Anyway...  Thanks for the info.  I
now have a 1M ram drive.  

I think it would also help if I posted all of my apple II questions
while I'm at home tinkering my my actual machines, instead of from
work...

David Empson wrote:
> 
> Dennis Jenkins <dennis@usb.com> wrote:
> 
> > Greg Buchner wrote:
> > > Dennis Jenkins wrote:
> > > >       In my IIgs, I can set the min/max size of a ram disk.  I have
> > > > 1024K of ram available for a ram disk.
> 
> It is important to note that if you want to use the RAM disk defined in
> the Control Panel, you should set the minimum and maximum sizes to the
> same value.  You can get strange problems including I/O ERROR messages
> if you use different values for these parameters.
> 
> (The ROM 3 IIgs only has a single parameter to set the size of the RAM
> disk.)
> 
> > > There are two RAM disks available on a IIGS under ProDOS8.  The one that
> > > comes up in what would be the Aux RAM part of a //e which is 64K and the
> > > IIGS RAM which comes up as /RAM5 which is usually found at S5, D2 unless
> > > you set it to be the boot drive at which point it becomes S5, D1.
> > >
> > > The 64K Aux /RAM (S3, D2) is there for compatibility, the /RAM5 is there
> > > to allow you to make use of the IIGS RAM under P8 as a disk drive.
> >
> >       I think that on my system that both are called "/RAM".
> 
> If that is the case, then something must have deliberately renamed /RAM5
> as /RAM.  When the control panel's RAM disk is created by the firmware,
> it starts out as a ProDOS volume called /RAM5.  It also supports Apple
> II Pascal: if Pascal is the first operating system to access the RAM
> disk then it will be set up as a Pascal volume called RAM5:.
> 
> Assuming the RAM disk size parameters are set to zero, then if you set
> either one to a nonzero value, save the control panel settings and
> restart the machine, the RAM disk will be created immediately.
> Subsequent changes to the control panel settings for the RAM disk are
> ignored unless you force a cold restart or power the machine off and
> back on again.
> 
> (To force a cold restart: start the self-test using Ctrl-Apple-Option-
> Reset, allow it to display at least one of the test pattern screens,
> then restart using Ctrl-Apple-Reset.  Note that you should not reset the
> computer while running GS/OS: always restart or shut down from the
> Finder before trying to do this trick.)
> 
> The ROM 3 IIgs has an option in its control panel to allow the RAM disk
> to be resized on the next restart, which saves you from having to force
> a cold start.
> 
> The RAM disk remains intact over any number of resets, warm restarts
> (Ctrl-Apple-Reset) or operating system changes, as long as you don't
> reset while the system is in the middle of writing to the RAM disk, and
> no buggy software overwrites the memory used by the RAM disk (which is
> outside the normal bounds of an 8-bit Apple II).
> 
> (If /RAM5 is erased by a ProDOS disk utility program to set up the boot
> blocks, you can even use it to boot the machine.  This isn't possible
> with the ProDOS auxiliary memory /RAM volume.)
> 
> After the RAM disk is created, it is a perfectly normal writable volume,
> so it is possible for any software to rename it using the normal ProDOS
> system calls.
> 
> My guess is that some ProDOS-8 application you are running has a bug in
> its code to support the use of auxiliary memory, and it is disconnecting
> the wrong RAM disk (/RAM5 instead of /RAM), ultimately recreating it
> with the name /RAM, resulting in a duplicate volume..
> 
> Have a look at the list of available volumes immediately after you have
> started the machine (e.g. boot directly into ProDOS-8 and then launch
> BASIC.SYSTEM before any other application).
> 
> >       If this is indeed the case, then why would prodos name them both
> > "/RAM"?
> 
> ProDOS itself isn't responsible for creating the /RAM5 volume.  As far
> as ProDOS is concerned, it is just a block device which happens to
> contain an already formatted volume.

-- 
dennis@usb.com                           Universal Savings Bank.

The three most dangerous things are a programmer with a soldering
iron, a manager who codes, and a user who gets ideas.