romkey@asylum.SF.CA.US (John Romkey) (05/03/90)
In article <144@avatar.UUCP> kory@avatar.UUCP (Kory Hamzeh) writes: >Does anyone know where I can get a hold of the 16550 tty driver for >xenix 386? I trying take advantage of a COM1 board which has one of these >chips in it. I've done this on asylum. The major benefit I was seeking was the receive FIFO so the system wouldn't drop characters when it was loaded. The Xenix serial port interrupt handler loops until there are no characters ready from the chip that interrupted, so this works fine. It doesn't take advantage of the transmit FIFO, though, where you can load up to 16 bytes of data to transmit per interrupt. All you have to do is enable the FIFO on the 16550 and you win. I've written a short program that does this; I run it at boot time. It needs a special device to access I/O space so that it can poke at the 16550. The Xenix kernel provides just such an undocumented device, but I couldn't remember what its major and minor device numbers were, so I wrote my own. If you want to take full advantage of the 16550, you'll need to do more than this. If you want to stop receiver overflows, my solution will work fine. I'll bundle this all up and send it out tonight. -- - john romkey USENET/UUCP: romkey@asylum.sf.ca.us Internet: romkey@ftp.com I could go on, but what's the use? You can't fight them with songs. Joe But think of this as a just another tiny blow against the empire. Jackson