[Coco] [CoCo] The Trials to disable RS232 Status

[David Ladd]

On Sun, Oct 1, 2017 at 3:19 AM, Arthur Flexser <flexser at fiu.edu> wrote:

> Another method of bypassing the RS232 status check is these pokes:
>
> POKE &HFF23,&H30: POKE&HFF22,&HF9: POKE&HFF23, &H34
>
> This will work on any model CoCo, does not depend on what ROM version
> exists in the machine, and does not require copying ROM to RAM.
>
> I works by using the PIA's data direction register to change the relevant
> status bit in $FF22 from an input to an output, so that the RS232 status is
> always seen as "ready" by Basic.
>

​Art, in one way that is nifty, but from the hardware perspective that
might be dangerous as might cause a short.  Personally last thing I need to
do is blow the bitbanger support hardware.​



>
> Art
>
> On Sun, Oct 1, 2017 at 3:37 AM, David Ladd <davidwladd at gmail.com> wrote:
>
> > Hello all,
> >
> > I thought I would share my small adventure tonight trying to find a way
> to
> > disable the RS232 Status check that basic does when you use LLIST or
> > PRINT#-2 on the bitbanger port.  So in my case I am using a CoCo 3, a
> > Windows system, Putty for Comm Software on Windows, USB to RS232 adapter,
> > and Cloud9's DriveWire cable.
> >
> > First thing I decided to do is try to dump my basic program to Putty via
> my
> > connections using LLIST.  Well at first I didn't see anything on the
> Putty
> > screen.  I then hit the spacebar key on Putty and all of a sudden I saw a
> > single character show up.  So I decided to old down the spacebar key to
> see
> > what happens.  Well the program listing started dumping only as long as I
> > held down the spacebar key.
> >
> > The reason for this is the serial line in on the bitbanger is used as the
> > RS232 Printer Status line.  So at this point I needed to find a way to
> > bypass this need to check for the RS232 Status Line since it isn't needed
> > in my case.
> >
> > So I started my research by looking through the PEEK & POKE's booklets
> that
> > have been around for a while and I didn't see anything from the CoCo1/2
> > ones or the CoCo 3 one I found.  So I decided to do some Googling and yet
> > still didn't find anything useful.
> >
> > So at this point I decided to look at the Color Basic Unraveled book
> since
> > it had LLIST & PRINT#-2 listed in its command list.  So looking through
> the
> > book I finally found the LINE PRINTER section.(Which starts @ Line # 0377
> > or Address $A2BF.)
> >
> > So I read through and found two instructions I figured would be safe to
> NOP
> > out.
> > First instruction at Line # 0381/Address $A2C7 and Line # 0408/Address
> > $A2F7.  Each of those instructions are two bytes.  A NOP is 1 byte.  So I
> > need to make sure I change all 4 bytes to the NOP instruction.  So I
> > quickly made a one liner to POKE the values I needed and then I would
> test
> > it to see if it worked.  Here is the one liner:
> > POKE &HA2C7,&H12:POKE &HA2C8,&H12:POKE &HA2F7,&H12:POKE &HA2F8,&H12
> >
> > So I tried LLIST and the basic program started dumping to Putty without
> the
> > need of me holding down the spacebar key.  I was happy.  Next I loaded my
> > program that I needed to dump some text out using PRITN#-2.  That worked
> > like a charm as well.
> >
> > So I figured I would share this bit of information just in case it might
> be
> > handy for someone else.
> >
> > Again though I want to stress this has only been tested on a real CoCo 3.
> > On a real CoCo 1 or CoCo 2 it would have to be in all RAM mode and second
> > the instructions would have to be in the same memory locations.  Which
> > there has been a few revisions of Color Basic.  So I can't say this will
> > work or not with a CoCo 1 or 2.
> >
> >
> > +-----------------------------------------------------------
> ------------+
> > | David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
> > | YouTube: http://www.youtube.com/user/PacoOtaktay
> |
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> |
> > | Websites: http://dwladd.com     &     http://www.theterrorzone.com
> |
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> |
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> |
> > |                                                                       |
> > | Do you have your CoCo 3 yet?                                          |
> > +-----------------------------------------------------------
> ------------+
> >
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>
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​

+-----------------------------------------------------------------------+
| David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
| YouTube: http://www.youtube.com/user/PacoOtaktay                      |
| YouTube Gaming Live: https://gaming.youtube.com/user/PacoOtaktay/live |
| Websites: http://dwladd.com     &     http://www.theterrorzone.com    |
| G+:  https://plus.google.com/113262444659438038657                    |
| G+:  https://plus.google.com/+DavidLaddPacoOtaktay                    |
|                                                                       |
| Do you have your CoCo 3 yet?                                          |
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