VAX 780 on eBay

[dave.g4ugm at gmail.com]

> -----Original Message-----
> From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of ben via cctalk
> Sent: 03 January 2022 02:00
> To: cctalk at classiccmp.org
> Subject: Re: VAX 780 on eBay
> 
> On 2022-01-02 6:28 p.m., Zane Healy via cctalk wrote:
> > On Jan 2, 2022, at 5:20 PM, Nigel Johnson Ham via cctalk
> <cctalk at classiccmp.org> wrote:
> >>
> >> I've always felt that in terms of performance the proper measure
> >> would have been VUPS/kW :-)
> >>
> >> That way my little MicroVAX 2 would be able to hold its head high!
> >
> > On that note a Raspberry Pi 2b running SIMH/VAX is about 1.6 VUPS.
> >
> > Zane
> >
> But can the Pi handle a gazillion students all time sharing at once @ 2400?
> How long was the VAX timesharing era as I suspect networked PC's come out
> soon after that.
> Ben.
> 


Ben,
Well if I remember properly the VAX couldn't at the time. I arranged for some folks from the place I worked to go on a VMS course at Liverpool University.
They came back cursing the VAX and VMS and the sluggish terminal response times and the dreaded "type behind".
With a few students on the VAX was great but get a decent load on and it crawled. 
The trouble was that VMS was usually used with the VAX handling character editing, so the scenario went something like this....

The user types an "a"...
The line driver says "what on earth do I do with this "a"? I know I'll send it to the user....
.. oh dear the users code is paged out...
... oh dear there are no free pages so I have to page out another user....
.. and page in the users.....
.. and send it the "a" ....
.. the user code says "oh and "a" has arrived, what do I do , I know I will echo it to the terminal and go to sleep....
.. in the mean time some one on the next terminal has typed a "B"....

The staff came back and said "how do we get a proper mainframe; we need an IBM with VM" where the editing is handled in the screen controller.....
... so we asked for a large amount of disk storage, allocated a small room and they got an IBM 4381 as at the time the VAX didn't have disks as big as the 3380-3 .....

Dave