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

[David Ladd]

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.


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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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