Um. As I recall, when you booted a 3270PC, it booted MS-DOS from the hard disk as usual. Early on in the boot procedure, it loaded some sort of 3270-terminal-operating-system which grabbed some memory somewhere, locked DOS out of it somehow and REBOOTED. DOS then loaded normally UNDERNEATH the terminal program. The 3270 PC had some extra keys on the keyboard - the function keys (24 of them) were where they are on a modern PC keyboard, but there was a block of keys where they were on the original PC keyboard. These keys did things like switch between your terminal session and your PC session. The keyboard plugged into the terminal card as well as the keyboard port, BTW - I think the terminal card filtered out stuff that wasn't meant for the DOS session. The point was, DOS never knew about the terminal unless you specifically piped data through the terminal program. IBM sold an API (Application Program Interface) which was a piece of software allowing programs running on the PC to type on the terminal, look at the terminal screen memory, etc. Very crude. File transfer software - not very good - was available too. The reason they were rare was that the IBM 3270 terminal protocol (SNA, Systems Network Architecture) was only used on IBM mainframes - not even on the System/3X minis. I don't know how it worked but it was EBCDIC for a start... Returning to the 5155, when I was working at IBM this was the cheapest complete system in the IBM range - it was much the same price as an XT (if not less) and it had a monitor built in. Many IBM employees bought them as an entry level system (IBM required us to sign a contract saying we wouldn't develop software for other than IBM machines - I don't know whether this would have survived a court case!) But there must be some around if only for that reason. Hope this helps! Philip. PS *** Off Topic *** Will Sam and Anthony please go and have their argument somewhere else? The first couple of posts about Anthony's personal testimony were interesting and related to computers. The subsequent argument about drugs and off-topic posts, not to mention mature adults of 17 and silly kids of 30 (I'm one of the latter FWIW) was not. Sam, you say Anthony has problems - but so do you. Will you stop jumping down everybody's throat as soon as the topic starts to drift, please? Finally, alcohol. Interesting points about Prohibition (which we didn't have over here). Thank you whoever posted them (even though off topic). Denatured alcohol here is still "Methylated Spirit" - i.e. it has had methanol added. It has also had pyridine (I think) added to make it look purple and taste foul, and it is therefore even more poisonous, but it doesn't leave a residue. On the subject of home-made booze, if you use the wrong sort of yeast, you may well get methanol in the ferment. During prohibition I'd guess that proper brewer's yeast was not easily available! Apparently potatoes are particularly susceptible, and this has given the traditional Irish spirit made therefrom, Poteen, a bad name for making you literally "blind drunk." Since I am a non-drinker I'd better say no more on that subject... Philip.