[geeks] Oldest OS Still Developed

[Geoffrey S. Mendelson]

On Wed, Oct 18, 2006 at 03:46:41PM -0400, Charles Shannon Hendrix wrote:
> No, early 1970s.  It was all in C by 1972 or so.

Ok, it's still 1970's.

> 
> > > 	- MVS
> > 
> > Early to mid 1960's 
> 
> No, it was not released until 1974.

OS/360 was available in 3 versions, a single task version, I think was
called PCP (Primary control program), MFT (multiple fixed tasks) and
MVT (multiple variable tasks). The difference between MFT and MVT was memory
allocation, MFT had fixed sized partitions, MVT had dynamicaly variable 
sized ones. 

MFT was expanded to use virtual memory for the 370/xx8 series (138/148/158/168)
and called OS/VS1. MVT was expanded and called MVS. 

Both had significant amounts of code from their predcessors. Both were 
"open source", you could get it on microfice. I know, I've seen it.

> > By 1969 you had TOS (which I think was no longer supported), DOS, OS/360,
> > ACP and VM/360.
> 
> DOS/VSE (*) is 41 years old this year, so that puts it at 1965.
> 
> * I think this is the right name, not DOS/VE, unless both were used.

There was DOS (disk operating system), a name used well before the 360.
I programmed an 1130 in 1968 that used an operating system called DOS
and I think there was a DOS for the 1401.

DOS was extended to become DOS/VS (disk operating system/virtual storage).
VSE (actually called DOS/VSE) was a extension of DOS/VS. There were other
nonIBM extensions one was called DOS/MFT. 

Until VSE and MVS/SP (MVS system product), the operating systems were free
and open source. If you had an non IBM computer (they just started about that
time), IBM would provide you the operating system for $100 a license fee,
but would not support it. 

Geoff.
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