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Re: Uthernet II manual updated, probe algorithm corrected

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On Sunday, 10 January 2016 13:11:29 UTC-8, David Empson  wrote:
> David Schmenk <dschmenk@gmail.com> wrote:
> 
> > On Saturday, 9 January 2016 18:07:22 UTC-8, David Empson  wrote:
> > > David Schmenk <dschmenk@gmail.com> wrote:
> > > 
> > > > On Saturday, 9 January 2016 13:35:47 UTC-8, D Finnigan  wrote:
> > > > > David Schmenk wrote:
> > > > > > 
> > > > > > David-
> > > > > > 
> > > > > > I read the pointer first and see if it gets incremented by a read
> > > > > > instead of assuming it starts at zero. Seems to work well for me.
> > > > > 
> > > > > Thanks for the suggestion. How much of a concern do you think it is
> > > > > to be blindly poking at the $C0 space? In other words, do you have
> > > > > personal experience or anecdotal evidence that other peripherals may
> > > > > be affected?
> > > > 
> > > > Well, there is always a chance it could mess something up. Reading is
> > > > usually somewhat benign - you may clear a status bit or something.
> > > 
> > > There are many cards where merely reading a soft switch will do
> > > something to it. Off the top of my head:
> > > 
> > > - A RAMFactor or similar will auto-increment its address register if you
> > > read its data register. In that case, it is probably innocuous, because
> > > the driver will set the address register before transferring data
> > > to/from it.
> > > 
> > > - Reading the input buffer register from a serial card will lose the
> > > received character.
> > 
> > That was the case that came to mind, it clears the character available status.
> > 
> > > - Disk ][ controller motor control is activated by reading $C0n9.
> > > 
> > > > The best approach is to probably look for a ROM signature in the slot
> > > > first, and skip it unless its slot 3. I don't know of any other phantom
> > > > ROM except for the //e 80 column card that would be present in the same
> > > > slot as the Uthernet. Multi-IO perhaps?
> > > 
> > > The Apple IIgs, where some slots have built-in firmware mapped to $CnXX
> > > but don't use the $C0nX space for their I/O. For some of these, the I/O
> > > addresses are accessible from a card in the slot while the internal
> > > firmware is active. (I don't know if I still have enough reference
> > > material handy to confirm the details - I've thrown out most of my Apple
> > > II books and manuals due to water damage a few years ago.)
> > 
> > Right, probably like the mouse firmware on a //c or IIIgs.
> > 
> > > 
> > > > Other than that, if I poke something that doesn't work out, I try to
> > > > restore the value I found when I got there. I've had better success with
> > > > the Uthernet II than the Uthernet I (which I can find the first time, not
> > > > afterwards).
> > 
> > Perhaps looking for a ROM *boot* signature would be better? There could be
> > phantom disk slots though. Does the 3.5 drive firmware do that for slot 5?
> > Ugh.
> 
> Certainly looking for the ROM signature of a Disk ][ controller or other
> bootable ProDOS/SmartPort devices would be a good start.
> 
> The 3.5 drive remapping logic is not in the firmware or hardware, it is
> done as a logical remapping within the ProDOS MLI.
> 
> ProDOS-8 1.2 and later map slot 5 drives 3 and 4 to slot 2 unit numbers,
> if there is a suitable card in slot 5, such as the //c or IIgs SmartPort
> controller, and nothing that looks like a disk controller in slot 2.
> This doesn't affect other cards such as a serial interface in slot 2,
> nor its I/O locations.
> 
> ProDOS-8 2.x extends this to remapping drives/volumes from SmartPort
> controllers in any slot to any "unused" slot, e.g a SCSI card in slot 7
> of a IIgs could use the unit numbrs for slots 1, 2, 3 (drive 1 only) and
> 4, potentially giving it nine units including the two from its own slot
> (assuming those slots had no disk controller and weren't already being
> used for "overflow" units from slot 5).
> 
> The other type of card that can be reliably detected by ROM signature is
> serial/parallel interfaces using the BASIC and Pascal firmware
> interface, which includes many 80-column cards.
> 
> -- 
> David Empson
> dempson@actrix.gen.nz

Thanks for the nice description. I'll look into incorporating the ROM signature into the probe algorithm.

Dave...

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Re: Uthernet II manual updated, probe algorithm corrected D Finnigan <dog_cow@macgui.com> - 2016-01-08 17:49 +0000
  Re: Uthernet II manual updated, probe algorithm corrected David Schmenk <dschmenk@gmail.com> - 2016-01-08 22:38 -0800
    Re: Uthernet II manual updated, probe algorithm corrected D Finnigan <dog_cow@macgui.com> - 2016-01-09 21:33 +0000
      Re: Uthernet II manual updated, probe algorithm corrected David Schmenk <dschmenk@gmail.com> - 2016-01-09 14:24 -0800
        Re: Uthernet II manual updated, probe algorithm corrected dempson@actrix.gen.nz (David Empson) - 2016-01-10 15:07 +1300
          Re: Uthernet II manual updated, probe algorithm corrected David Schmenk <dschmenk@gmail.com> - 2016-01-10 07:56 -0800
            Re: Uthernet II manual updated, probe algorithm corrected dempson@actrix.gen.nz (David Empson) - 2016-01-11 10:11 +1300
              Re: Uthernet II manual updated, probe algorithm corrected David Schmenk <dschmenk@gmail.com> - 2016-01-11 08:59 -0800

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