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Re: What makes the OS for QL any better, different, unique ?

Posted: Sat May 25, 2019 6:56 am
by 1024MAK
How are we defining multitasking?

Only the Sinclair ZX81 could be described as a very limited multitasking system because in normal (slow) mode the CPU was constantly (as far as the user was concerned) switching between running the users program and generating the serial data stream to maintain a steady non flickering video picture.

Is it anything like modern multitasking systems, of course not. But CPU technology has moved on rather a lot.

Mark

Re: What makes the OS for QL any better, different, unique ?

Posted: Sat May 25, 2019 1:55 pm
by stephen_usher
Arnould wrote:Also look at MS Xenix (was it the name ? I do not remember correctly) : total failure.


Xenix was supposed to be MSDOS 3 but was killed by it not being backwardly compatible with MSDOS 2 and hence didn't run Lotus 123. At the time business wouldn't buy anything which didn't run that spreadsheet as it was the only package they thought mattered.

MSDOS 2 introduced transitional feature to allow the transition in which the command "switch" character and directory separator could be changed to '-' and '/' respectively so as to match the UNIX usage. There was a flag in the system variables to tell applications which version to use. However, almost all applications ignored this and hard coded '/' and '\' in their code.

MSDOS 3 had partial support for this but by that time even Microsoft weren't following their own rules, especially when Xenix was relegated to a specialist product.

Re: What makes the OS for QL any better, different, unique ?

Posted: Sat May 25, 2019 5:15 pm
by Ralf R.
Xenix was used on Siemens computers here in Germany and I remember to try (and found via MausNet) someone, to copy all those text files for use on WIN 3.1.

Re: What makes the OS for QL any better, different, unique ?

Posted: Mon May 27, 2019 5:02 pm
by Arnould
Hello Stephen,

I did not know that Xenix was foreseen to become MS-DOS. However if they could not make a "simple" system like MS-DOS compatible with an "advanced" system like Xenix, certainly based on all the best theories about system software, then:

- either they had utterly bad programmers at Microsoft,
- or Xenix was an uncontrolable total mess that never worked well enough.

I would say the second option must have been true. Because of that team of thinking/eating philosophers not even able to afford 2 forks per person.

Re: What makes the OS for QL any better, different, unique ?

Posted: Mon May 27, 2019 5:53 pm
by tofro
What I recall on Xenix is that it was intended to be the Standard OS for PCs, (later, the same plan applied to OS/2) which does not necessarily mean MSDOS 3. (Just like OS/2 was not necessarily planned as a replacement for MSDOS at all.)

Considering the last stand-alone version of MS-DOS (6.22) was released in 1994, MS-DOS lived way longer than Xenix inside MS (last MS version released in 1985, after that it went to SCO [of later dubious fame]).

Xenix required at least 256kB RAM and a harddisk - something which simply couldn't be expected "standard" in the early 1980s. MSDOS had to stay around for quite a bit longer... In 1983, MS started development on OS/2 - and lost interest in Xenix.

The Xenix for Siemens PC was actually called "Sinix" - Which was based on Xenix.

Tobias