IBM Portable Personal Computer (and other things)

From: Philip.Belben(a)powertech.co.uk To: Discussion re-collecting of classic computers

Subject: Re[2]: IBM Portable Personal Computer (and other things) Date: Monday, January 26, 1998 10:44 AM > I'm not that impressed with the 3270pc. I bought it because I wanted > stuff out of it, but it was all pretty much proprietary (and covered > in dust and old) lots of wire wrapping and jumpers, so I just left it > alone. Now I use it to test Linux-16. > > The REAL question is, if IBM used these as terminals which could run > software, what did they have in them allowing them to use the network > ports? I mean that was 1984, DOS might have had some hooks, but they > would have sold it. > > Were these running XENIX/86, CPM86, or what? Anyone know? Anyone have

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.