C++ and RS232 port

Welcome back,
another question from a newbe.
Has anyone experimented with programing RS232c port (standard serial port) of the computer?
If so, what is the maximum transfer rate I can get from it? I was trying to get something like 250kb/s but something is definetely wrong with the transfer as the top I can get is 19200b/s.
Oh, I must say I make alink to a Atmel uP.
If anyone has any suggestions, please do.
Thanks
Marek

You won't get something like 250 kilobits...serial ports are limited to about the speed of a modem if I recall correctly. Could be that 19 kilobits is the limit of the interface, I just can't remember.

Hi
strange thing because so far I have reached 128kbits without greater problems. I was just wondering if there is any possibility of doubling it any more. Seems that either 128kbits is the limit or that the uP I am using has such limit.
Nevertheless, I had a suggestion today that LPT port is much simpler to cope with since it can handle 12 bit parallel transfer up to 10Mbits/sec and programming it is much easier.
Well, today I will have a long night with C++ from what I see.
Perhaps You have anything on programing LPT port under WIN 2000??
Best wishes and thanks for the post
Marek

Sorry, I've never really programmed anything in rs232 or lpt beyond toying around, so I don't have anything to really show you.

If you were getting higher transfer rates, maybe you were using a protocol with text compression?

Welcome back
The strange thing is that there is no compression.
All I used was a 6.61MHz quarzt, 90AT8535LS uP, one meter cable for RS232c standard and that was all. No compression. All I was using was the Terminal within the Bascom AVR software and I made uplink on 128kbits. Since it was working fine and I did not get any errors, I assume that the link was actually running at such speed. Once I tried to switch to 256k, it stopped responding.
Nevertheless, I have been sitting the whole night tryign to work out the LPT port and I think I have some good results about it. Once I have done something usefull, I will poresent it here so that everyone can have a look at it.
Best wishes
Marek