More like a score of systems (the MS windows stuff is also different from release to release). So we got W98, W2k, Wxp, WNT, Wme and WinCe, FreeBSD, NetBSD, OpenBSD, Dragonfly, Linux, Linux, Linux Solaris...
Yea, that's the word. Thanks :-)
Yes, DEC went through this but managed to make a mess of it. Some of it...
Wang had a business model that had to support everything they ever shipped in real time. There wasn't any process nor atbreastude for phasing out of old features or gear support. Every once in a while, code has to be cleaned up especially if it still has in-line code for gear that will never be used again. Note well that I've been told my opinion about this was nonsense...about a year before Wang choked.
One of the more frustrating times I've had in the biz is bit gods not being able to think about bit flows beyond their code. This has everything to do with the bits involved from getting a project started (which includes acquiring information from customers) to shipping the final product to customers installing and using these bits back to customers asking for changes and new things.
I understand how and why this approach is taken but it doesn't address long term evolutions of code nor hardware. Response to changes in customers' uses and manufacturing methods is almost impossible. Just handling bit flows would take 20 people-ship which would eventually evolve to 20 people-customer application. No hard-software biz can make money from that. Note that those 20 people do not include mangagement, personnel, nor infrastructure manpower. What it boils down to is having a product linecustomer use which makes a muthaf***in mess. Just the storage of sources-customer use would be mind boggling and there didn't exist disk capacity back then to do all of this.
But there are implicit quality controls all through the food production and transportation infrastructure. There is none with Micpoo. There is also the Wendy's across the street if you want to eat something more tailored to your taste. Unix is not at this point..yet. Users still have to do some of the cooking for themselves.
The BIOS basically is the boot rom plus some hooks for video-comm system calls. They were invented back in the old days of the 8086-8088 when the old IBM PC had BASICA in...