On Mon, 25 May 2020 at 05:30, Fred Cisin via cctalk <cctalk@classiccmp.org> wrote: > > I played briefly with Xenix on an XT (or MAYBE an AT) on a 15MB? drive > partition. MS-DOS was a better match for that hardware.
Never tried Xenix on an XT, but it was the 2nd OS on my PC-AT in my first ever job. That machine was very limited (512 KB RAM, 20 + 15 MB ST-506 disks), but on a well-specced 286, it was quite a decent little Unix. It could properly use an 80286 and up to 16 MB of RAM, something DOS in the 286 era couldn't do -- MS-DOS 3.3 did not even come with a disk cache. (Not counting FILES=20 BUFFERS=20 in CONFIG.SYS!) IBMs came with an installable driver called, I think, IBMCACHE.SYS. This used extended RAM (above 1MB) as a hard disk cache, without XMS or HIMEM.SYS or any of that. I played with it and was amazed by the results. I started enabling it by default on customers' machines. Most were happy but some had the habit of just turning off -- DOS didn't really have a shutdown routine. Some, I could train to press Ctrl-Alt-Del before turning off. Some I couldn't, so I had to disable the disk cache. But for those that could learn and adapt, it made DOS _much_ faster, and on a 1MB PS/2 Model 50 or 60, it was about the only thing you could do with the extra 386 KB of RAM before MS-DOS 5 came out. So the fact that Xenix could use 4 MB or 8 MB in a 286 seemed like wizardry. > OS/2 (Gordon Letwin at Microsoft) was a substantial step up for MS-DOS. > Once they added "Windows For Os/2"/"Presentation Manager", . . . > BUT, then NT was not a direct transition from OS/2. > And, around 1986? IBM started pushing OS/2 with PS/2 (had they bought OS/2 > from Microsoft by then?) No, not yet. OS/2 1.0: 1987. Text-only. OS/2 1.1: 1988. Finally got the PM GUI. OS/2 1.2: 1989. Started to be a bit usable. OS/2 1.3: 1990. Same year as Windows 3.0, which spelled its doom. OS/2 2: 1992. 1 year before Windows NT 3.1. First IBM-only version, first 386 version. AFAIK IBM never _bought_ OS/2. MS walked away from the co-development deal after Windows 3.0 was a huge hit -- 3 million copies in 1990 alone. OS/2 2 was the 386 version. OS/2 3 was to be a portable version. There was next to nothing written, but MS commissioned a line of Intel i860 RISC boxes (codenamed N-10) to prototype it on. When they hired Dave Cutler & team in 1988, that was the product he was given to salvage. It became OS/2 NT which became Windows NT. -- Liam Proven – Profile: https://about.me/liamproven Email: lpro...@cix.co.uk – gMail/gTalk/gHangouts: lpro...@gmail.com Twitter/Facebook/LinkedIn/Flickr: lproven – Skype: liamproven UK: +44 7939-087884 – ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053
