[Coco] Cryptic BASIC program

[Salvador Garcia]

Since I am  master of misunderstanding this is entirely possible.  Then this program was only useful once to verify that the computer was set to 64K. I did not have to run it every time I started the CoCo.

How were the 64K used? Or better said, how was the Ram used? Since part of the address space went to the ROM(s) what happened to the RAM that was addressed in the same space os the ROM(s)?

Thanks, Salvador



-----Original Message-----
From: Arthur Flexser <flexser at fiu.edu>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Sun, Sep 27, 2015 2:04 pm
Subject: Re: [Coco] Cryptic BASIC program


You probably misunderstood the Radio Shack guy, who likely was telling you
that
running the program would verify that the machine indeed had 64K.  (It
actually
checks only that one aspect of installing a 64K upgrade, moving a
jumper, was
done, not that the RAMs are good.)   Or else the Shack guy
himself was confused,
which would not be unusual, even back then.
(Nowadays, you can just assume they
know nothing about computers.)

Art

On Sun, Sep 27, 2015 at 2:45 PM, Salvador
Garcia <
ssalvadorgarcia at netscape.net> wrote:

>
> Thanks all for your feedback
and explanation of the code.
>
> Although I understood all that was explained, I
am not sure exactly what
> effect this small program has when I run it. I
remember the Radio Shack guy
> telling me that I had to run it in order for the
CoCo I to recognize all
> 64K; however, given the 1600/16000 discrepancy, I am
not sure what the code
> as given actually does. I need to get more stuff done,
but if I have time I
> will unpack the CoCo I and try out both versions of the
code to see if I
> can detect any difference.
>
> Again, thanks, I appreciate
your time in effort in helping me out.
>
> Salvador
>
>
>
> -----Original
Message-----
> From: Arthur Flexser <flexser at fiu.edu>
> To: CoCoList for Color
Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Sat, Sep 26, 2015 10:56 pm
>
Subject: Re: [Coco] Cryptic BASIC program
>
>
> On Fri, Sep 25, 2015 at 11:18
PM, Darren A <mechacoco at gmail.com> wrote:
>
> >
> > It
> is not a good
substitute for a real RAM test program. It merely checks
> > the
> jumper
setting which Basic uses at initialization time to decide how to
> >
> configure
the SAM chip.  I'm not sure if the CoCo will even boot correctly
> >
> when the
SAM is configured for the wrong type of RAM chip.
> >
>
> I recall you could
>
fool a 32/64K CoCo 1 into setting the SAM for 4K by
> pressing the reset
button
> with shift and break held down, so
> apparently CoCo Basic will
tolerate a wrongly
> set SAM configuration in at
> least some cases.
>
> (This
was the basis of the
> shift-break-reset method of breaking out of a
>
copy-protected program, allowing
> certain special methods of removing the
>
copy protection to be employed.  Not
> usable with Color Basic 1.2 (?) and
>
above due to the elimination of checking for
> the 4K possibility in later
>
versions of Basic's warm start routine.  After
> shift-break-reset, most
>
commands give an out-of memory error in the 4K
> configuration, but CLOADM
> and
EXEC work, so you can regain control of the
> machine and switch back to
> 64K
SAM mode.)
>
> Art
>
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