You might have to use native OS tools to do that. On Unix, that will be 'stty'; on Windows, you'd have to use native Windows tools to do that; if you go to the Device Manager, select your serial port, and click on 'Properties', it has a tab ('Port Settings') for that (or, should I say, it used to - not sure about the most recent versions, they're making it all smart-phone like for brain-dead lusers). I'm kind of surprised to hear that; I assumed that PDP11GUI can download binaries, and for that, 8-bit is kind of necessary? Side-story: when I started bringing up my -11's, the first one I did was an -11/23. So I needed a way for my Windoze box to talk to the -11's console line, for ODT. I was too lazy to figure out how to use some existing software, so I decided to write some. I wanted to be able to use it (later) to talk to one -11 from another, and I didn't know how to do complex terminal hacking under Windoze anyway, so I decided to write it under Unix. V6, to be exact (I consider all later versions to be unholy perversions - well, V7 isn't too bad, I guess), running on Ersatz11 on the Windoze box. Later, I wanted to be able to load .LDA files, which are 8-bit binary. One problem. Native Unix V6 doesn't have the ability to output 8-bit binary over a serial line (or input it, for that matter). When I first started using V6 at MIT, the DSSR people had already totally re-written the TTY driver, and added that capability, so I never ran into this problem before. Also, the native V6 stty() call isn't very flexible, and there are no spare mode bits. So they'd added a new system call, ttymod() (sort of like ioctl(), but done before it), to control all their wonderful extensions. I decided not to replicate that, but rolled my own upwardly compatible extension to stty(), which adds all that extended semantics. From there, it wasn't too much work to get sending the absolute loader down the serial line in its original binary form (which means all the old console bootstraps work, too), and using that to load .LDA files. Noel