[Coco] CoCoRX

[Mike Delyea]

Total hardware noob questions follow.  Does the coco do a hardware test at
statrtup?  And passing that test, boots to the familiar coco screen with
copyrights displayed.  I know that if a disk controller has failed (for
whatever reason), you will only get the DECB screen.  And if the ECB ROM
fails you will only get the Colour Basic screen.  Given the limitations of
the coco, wouldn't you need a cartridge to bypass the coco rom (in the case
that all appears OK at boot but fails later)?  To reiterate, I am aware of
but know NOTHING about hardware hacking, PLCs, FPGAs, PICs or even RasPis.
Logic?  thats something Spock did.


On Fri, May 29, 2015 at 11:11 PM, Dave Philipsen <dave at davebiz.com> wrote:

> Yes, just an idea I threw out there...maybe not that viable.
>
> On May 29, 2015 11:04 AM, "John W. Linville" <linville at tuxdriver.com>
> wrote:
> >
> > I'm not sure that is a realistic failure scenario, but I guess it
> > c
>
> ould be possible...  Still, all you would get is a random crash and > only
> if the mysterious writer overwrote code that still gets executed > and even
> then it depends on what value gets written. > > YMMV, but I would favor the
> methodical test with the program hosted > in ROM. > > John > > On Fri, May
> 29, 2015 at 12:14:48AM -0400, Dave Philipsen wrote: > > Mmmmm....it's
> impossible to overwrite ROM.  A program could run just fine in ROM while
> bad hardware is trying to overwrite the ROM but can't. The same program
> program fails miserably when you run it from RAM.  It's not always easy to
> find RAM errors because you have to write different bit patterns and even
> different contents into 'adjoining' cells but programs are generally
> unforgiving and have a nice variety of bit patterns in their opcodes.  A
> single bad bit of memory that holds a program will sometimes rear its head
> more quickly than a methodic test of the same memory. > > > > Dave
> Philipsen > > > > > On May 28, 2015, at 5:10 PM, John W. Linville wrote: >
> > > > > >> On Thu, May 28, 2015 at 04:25:14PM -0400, Dave Philipsen wrote:
> > > >> You could write the program in position independent code and offer
> on option for it to copy itself from cart ROM to internal RAM and run it
> from there....just an idea....or it could copy itself to RAM in the same
> position and then switch over to 64k mode.... > > >> > > >> I'm sure you
> could get enough people to contribute code to make it work. > > > > > >
> What would be the purpose of doing that?  You would already need to > > >
> test the RAM before it makes sense to do that, and the ROM would have > > >
> to work for the program to run at all...? > > > > > > John > > > -- > > >
> John W. Linville        Someday the world will need a hero, and you > > >
> linville at tuxdriver.com            might be all we have.  Be ready. > > >
> > > > -- > > > Coco mailing list > > > Coco at maltedmedia.com > > >
> https://pairlist5.pair.net/mailman/listinfo/coco > > > > -- > > Coco
> mailing list > > Coco at maltedmedia.com > >
> https://pairlist5.pair.net/mailman/listinfo/coco > > -- > John W.
> Linville Someday the world will need a hero, and you >
> linville at tuxdriver.com might be all we have.  Be ready. > > -- > Coco
> mailing list > Coco at maltedmedia.com >
> https://pairlist5.pair.net/mailman/listinfo/coco
>
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