[Coco] [CoCo] The Trials to disable RS232 Status
David Ladd
davidwladd at gmail.com
Sun Oct 1 03:37:36 EDT 2017
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 |
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| Do you have your CoCo 3 yet? |
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