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

[Arthur Flexser]

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

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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> |                                                                       |
> | Do you have your CoCo 3 yet?                                          |
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