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Porting GSOS to Single board computers

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  Porting GSOS to Single board computers TheJ <thej@shaw.ca> - 2015-08-05 20:27 +0000
    Re: Porting GSOS to Single board computers Steve Nickolas <usotsuki@buric.co> - 2015-08-06 06:01 +0200
      Re: Porting GSOS to Single board computers Michael J. Mahon <mjmahon@aol.com> - 2015-08-05 23:46 -0500
        Re: Porting GSOS to Single board computers TheJ <thej@shaw.ca> - 2015-08-06 05:22 +0000
          Re: Porting GSOS to Single board computers Stavros Karatsoridis <skaratso@gmail.com> - 2015-08-06 06:31 -0700
            Re: Porting GSOS to Single board computers TheJ <thej@shaw.ca> - 2015-08-06 17:28 +0000
              Re: Porting GSOS to Single board computers Stavros Karatsoridis <skaratso@gmail.com> - 2015-08-06 13:19 -0700
              Re: Porting GSOS to Single board computers wssimms@gmail.com - 2015-08-06 17:55 -0700
    Re: Porting GSOS to Single board computers Gordon Henderson <gordon+usenet@drogon.net> - 2015-08-06 11:30 +0000
    Re: Porting GSOS to Single board computers Benoit0123 <bgilon@free.fr> - 2015-08-10 14:56 +0000
      Re: Porting GSOS to Single board computers sicklittlemonkey <nick.westgate@gmail.com> - 2015-08-12 05:18 -0700
        Re: Porting GSOS to Single board computers David Schmidt <schmidtd@my-deja.com> - 2015-08-12 16:00 -0400
        Re: Porting GSOS to Single board computers Michael Black <et472@ncf.ca> - 2015-08-13 00:22 -0400
          Re: Porting GSOS to Single board computers wssimms@gmail.com - 2015-08-12 17:49 -0700
            Re: Porting GSOS to Single board computers misterlott@gmail.com - 2015-10-26 14:47 -0700
              Re: Porting GSOS to Single board computers Don Bruder <dakidd@sonic.net> - 2015-10-26 15:27 -0700
            Re: Porting GSOS to Single board computers John Brooks <jbrooks@blueshiftinc.com> - 2015-10-26 16:24 -0700
              Re: Porting GSOS to Single board computers D Finnigan <dog_cow@macgui.com> - 2015-10-27 14:29 +0000
                Re: Porting GSOS to Single board computers Michael J. Mahon <mjmahon@aol.com> - 2015-10-27 17:08 -0500
                  Re: Porting GSOS to Single board computers D Finnigan <dog_cow@macgui.com> - 2015-10-28 00:51 +0000
                    Re: Porting GSOS to Single board computers Michael J. Mahon <mjmahon@aol.com> - 2015-10-28 15:06 -0500
                Re: Porting GSOS to Single board computers misterlott@gmail.com - 2015-10-30 12:40 -0700
              Re: Porting GSOS to Single board computers scott@alfter.diespammersdie.us (Scott Alfter) - 2015-10-28 17:43 +0000
                Re: Porting GSOS to Single board computers Michael Black <et472@ncf.ca> - 2015-10-28 14:59 -0400
                  Re: Porting GSOS to Single board computers scott@alfter.diespammersdie.us (Scott Alfter) - 2015-10-29 16:16 +0000
                    Re: Porting GSOS to Single board computers Gordon Henderson <gordon+usenet@drogon.net> - 2015-11-01 10:55 +0000

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#26097

D Finnigan <dog_cow@macgui.com> wrote:
> Michael J. Mahon wrote:
>> D Finnigan <dog_cow@macgui.com> wrote:
>>> John Brooks <jbrooks@blueshiftinc.com> wrote:
>>>> 
>>>> And then there's the reliability of the emulators. I'm often bumping
>>>> into
>>>> compatibility problems with current emulators. If you want to make the
>>>> Apple II do something cool and novel the emulators cannot be trusted to
>>>> be 100% accurate.
>>>> 
>>> 
>>> Worth repeating as it's the reason why I use emulators as little as
>>> possible, and don't do any development on them.
>>> 
>> 
>> Interesting. 
>> 
>> I frequently use AppleWin for development, and have not encountered any
>> accuracy issues. 
>> 
> 
> I've been doing a lot of development for the Uthernet II recently….. :-)
>

Any project requiring additional hardware (unemulated) is unsuitable for
development on an emulator. And timing-critical routines are often a
problem in emulation. 

My sound synthesis code and NadaNet are both unsuitable for emulated
testing, but they "cross develop" nicely using emulated tools. 
-- 
-michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com

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#26100

On Tuesday, October 27, 2015 at 10:32:04 AM UTC-4, D Finnigan wrote:
> John Brooks <jbrooks@blueshiftinc.com> wrote:
> > 
> > And then there's the reliability of the emulators. I'm often bumping into
> > compatibility problems with current emulators. If you want to make the
> > Apple II do something cool and novel the emulators cannot be trusted to be 100% accurate.
> >
> 
> Worth repeating as it's the reason why I use emulators as little as
> possible, and don't do any development on them.

Amen to that, sir!

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#26095

In article <50ef7284-a8de-4174-a923-b6252572ce5a@googlegroups.com>,
John Brooks  <jbrooks@blueshiftinc.com> wrote:
>But yes, it would be possible in theory to standardize the RPi HW, OS,
>USB devies, & drivers. But what about users who have data on 5.25, 3.5,
>Iomega ZIP drives, or custom I/O cards?

Zip drives are available in USB.  

As for floppies, while there are gadgets such as the FC5025 that attach
floppy drives to USB for purposes of reading old formats, perhaps emulators
would be better served by a gadget that implements more of the floppy-drive
interface hardware for a targeted machine.  For an Apple II floppy
interface, you'd probably want a Disk II controller workalike, plus a 6502
and a small amount of RAM.  Transfer disk-read code into the adapter's RAM
from the host, and you can read/write/format disks from within an emulator
that supports the adapter.

  _/_
 / v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/           Top-posting!
 \_^_/                              >What's the most annoying thing on Usenet?

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#26096

On Wed, 28 Oct 2015, Scott Alfter wrote:

> In article <50ef7284-a8de-4174-a923-b6252572ce5a@googlegroups.com>,
> John Brooks  <jbrooks@blueshiftinc.com> wrote:
>> But yes, it would be possible in theory to standardize the RPi HW, OS,
>> USB devies, & drivers. But what about users who have data on 5.25, 3.5,
>> Iomega ZIP drives, or custom I/O cards?
>
> Zip drives are available in USB.
>
> As for floppies, while there are gadgets such as the FC5025 that attach
> floppy drives to USB for purposes of reading old formats, perhaps emulators
> would be better served by a gadget that implements more of the floppy-drive
> interface hardware for a targeted machine.  For an Apple II floppy
> interface, you'd probably want a Disk II controller workalike, plus a 6502
> and a small amount of RAM.  Transfer disk-read code into the adapter's RAM
> from the host, and you can read/write/format disks from within an emulator
> that supports the adapter.
>
But the PI is so much faster than the Apple II, it can probably handle 
transfers so much better.  Given the hardware built into the PI, one can 
maybe just build some of the floppy drive board.  I don't know if it works 
fast enough that interrupts aren't a problem.

   Michael

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#26098

In article <alpine.LNX.2.02.1510281457290.31594@darkstar.example.org>,
Michael Black  <et472@ncf.ca> wrote:
>On Wed, 28 Oct 2015, Scott Alfter wrote:
>
>> In article <50ef7284-a8de-4174-a923-b6252572ce5a@googlegroups.com>,
>> John Brooks  <jbrooks@blueshiftinc.com> wrote:
>>> But yes, it would be possible in theory to standardize the RPi HW, OS,
>>> USB devies, & drivers. But what about users who have data on 5.25, 3.5,
>>> Iomega ZIP drives, or custom I/O cards?
>>
>> Zip drives are available in USB.
>>
>> As for floppies, while there are gadgets such as the FC5025 that attach
>> floppy drives to USB for purposes of reading old formats, perhaps emulators
>> would be better served by a gadget that implements more of the floppy-drive
>> interface hardware for a targeted machine.  For an Apple II floppy
>> interface, you'd probably want a Disk II controller workalike, plus a 6502
>> and a small amount of RAM.  Transfer disk-read code into the adapter's RAM
>> from the host, and you can read/write/format disks from within an emulator
>> that supports the adapter.
>>
>But the PI is so much faster than the Apple II, it can probably handle 
>transfers so much better.  Given the hardware built into the PI, one can 
>maybe just build some of the floppy drive board.  I don't know if it works 
>fast enough that interrupts aren't a problem.

Reading/writing floppy disks is a real-time task.  On the Apple II, it gets
the processor's undivided attention.  The processor in the Raspberry Pi is
clocked much faster (700x or more) and probably does more work per clock
cycle (the Cortex-A7 in the Raspberry Pi 2 is even a superscalar design),
but can the OS (usually Linux) provide the needed periodic access on a
reliable-enough basis to make reading floppy disks in software work? 

The reason I suggested throwing a processor and some RAM into the interface
was to offload this timing-critical task.  You can crib some known-working
code from ProDOS or whatever and just pass blocks back and forth over USB. 
For reading copy-protected media, you can send a different routine over;
this more than likely means that existing tools for working with such disks
most likely wouldn't work.  

I suppose that conceptually, the idea is similar to a Commodore 1541 with a
USB interface instead of the butchered version of IEEE-488 that that drive
used.

  _/_
 / v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/           Top-posting!
 \_^_/                              >What's the most annoying thing on Usenet?

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#26106

In article <n0tgod$5k7$1@dont-email.me>,
Scott Alfter <scott@alfter.diespammersdie.us> wrote:
>In article <alpine.LNX.2.02.1510281457290.31594@darkstar.example.org>,
>Michael Black  <et472@ncf.ca> wrote:
>>But the PI is so much faster than the Apple II, it can probably handle 
>>transfers so much better.  Given the hardware built into the PI, one can 
>>maybe just build some of the floppy drive board.  I don't know if it works 
>>fast enough that interrupts aren't a problem.
>
>Reading/writing floppy disks is a real-time task.  On the Apple II, it gets
>the processor's undivided attention.  The processor in the Raspberry Pi is
>clocked much faster (700x or more) and probably does more work per clock
>cycle (the Cortex-A7 in the Raspberry Pi 2 is even a superscalar design),
>but can the OS (usually Linux) provide the needed periodic access on a
>reliable-enough basis to make reading floppy disks in software work? 

There are other issues too - e.g. DRAM refresh. So even if you can turn all
interrupts off, code on the "bare metal" then the memory refresh will get
in the way. On the Apple II it is deterministic - ie. every half cycle, on
the Pi it's not - as it's done in blocks and the video refresh gets in there
at times too and steals a few cycles...

There are a few ATmega based solutions to reading Disk II - that would be my
approach; use the ATmega to read block/tracks and feed that to e.g. an emulator
on the Pi. Won't work for copy protected disks though, but for day to day
use, I'm sure it can be made usable.

Gordon

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