[HECnet] How long has your 20 been up?

[Thomas DeBellis]

That just goes to show you how much time I spent on 16 bit platforms.

Or maybe not and I should have known better.  The Tops-20 uptime program 
is actually inspired by a program of the same name that I first wrote 
for OS/2 1.3.  This was back when OS/2 was running on a 286 in protected 
mode and we were pretty amazed to see what an AT could actually do (once 
you put on a 14 MB  Extender board).

The API to get the uptime was interesting; you called DosGetInfoSeg to 
have OS/2 put a selector into your address space with useful bits of 
information. This is quite similar in concept to the Tops-20 SPY UUO and 
was thus a pleasant surprise.  The system uptime was kept in 
milliseconds in a 32 bit field and had you had to strobe it out as two 
16 bit words.

So I had to do cascaded division to convert and extract the fields I wanted.

Where things really got interesting was when I converted the program to 
run in family mode, meaning the same code would execute under OS/2 and 
DOS.  The BIOS time base is 18.2065 ticks per second.  Converting that 
to thousands of milliseconds got me out to 48 bit partial results and 64 
bit intermediate totals.

Of course, I could have used the 287 and had the floating point unit 
take care of this, but where was the fun in that?  Besides, my code ran 
faster.  Heh...

> ------------------------------------------------------------------------
> On 1/20/22 1:57 PM, Paul Koning wrote:
>
> Not quite. The acronym actually says that it is not solar time, it's 
> Greenwich MEAN Time. UTC is merely the new name for GMT, obviously 
> adopted to keep the French from fulminating. (It's amusing that, just 
> like "ISO", UTC isn't an acronym; it matches neither the English nor 
> the French initials.)
>
> On Thomas DeBellis's observation that system programmers don't 
> understand long arithmetic, that's obviously not true for PDP-11 
> programmers. (You can't deal with non-tiny disks if you don't 
> understand this.)
>
> paul
>> ------------------------------------------------------------------------
>> On Jan 20, 2022, at 12:20 PM, Peter Lothberg<roll at stupi.com>  wrote:
>>
>> GMT is solar time! (and not used...)
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