Old farts and new Linux

[Gordon Keehn]

Hugh Foster wrote:

> Commodore Pet for me - builtin tape drive - and then  the mighty 
> Sinclair Spectrum, then DEC/VAX... VAX/VMS was a sort of corporate 
> LINUX, I suppose, take UNIX and rewrite it the way we like it. Then PCs, 
> and now my toe in the Linux pool. And the young Oracle "programmers" 
> sitting around me panic when they see a command prompt! :)

Actually, I believe VMS was a superset of RSX-11M (IIRC RSX stood for 
Realtime System eXecutive).  In another incarnation I had to write some 
special interrupt service drivers for a multi-channel A-D converter hung 
on a PDP-11/34.  Cute once I discovered that the first thing you had to 
do when the driver got control was DISABLE INTERRUPTS.  Then next thing 
was clear the interrupt (actually clearing a bit in the I/O page) and 
then reenable interrupts.  If you forgot the first step, in the time it 
took to clear the bit, you blew the kernel stack as the ISR was driven 
again, and again, and again, and ...