[net.micro.cbm] modem - assembly

rfox@sdcsvax.UUCP (Richard Fox) (01/07/85)

I have a question dealing with open files in assembly language and the rs232.

I would like to re-write my basic term program into assembly language.

To do this I need to have 2 opened output devices and 2 opened input devices.
The routines will be structured like this:

rs232 - input - open
screen -output - open

---------------------
keyboard - input - open
rs232    -output - open


To keep switching my input and output files do I have to close the rs232
and then reopen it or can I just keep switching which channel is now the
input/output channel without closing the other one?


All suggestions welcomed

thanks
rich

dwl10@amdahl.UUCP (Dave Lowrey) (01/09/85)

> 
> rs232 - input - open
> screen -output - open
> 
> ---------------------
> keyboard - input - open
> rs232    -output - open
> 
> 
> To keep switching my input and output files do I have to close the rs232
> and then reopen it or can I just keep switching which channel is now the
> input/output channel without closing the other one?

There is no need to CLOSE and OPEN the files to switch back and forth. Use
CHKIN to switch input files, and CHKOUT to switch output files. Just load
the X register with the file number (not device number) of the desired
input/output file then call the routine.
-- 
-----------------------------------------------------------------------
                               Dave Lowrey

"GORT...Klatu borada niktow"

                                   ...!{nsc,sun,hplabs,ihnp4}!amdahl!dwl10

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