VAX 780 on eBay

[John Forecast]

> On Jan 2, 2022, at 9:14 PM, Grant Taylor via cctalk <cctalk at classiccmp.org> wrote:
> 
> On 1/2/22 6:59 PM, ben via cctalk wrote:
>> But can the Pi handle a gazillion students all time sharing at once @ 2400?
> 
> I think that will depend on how you connect the serial terminals.
> 
> I know that it's possible to establish network connectivity to serial terminal servers.  I don't know how many of those terminal servers can be connected to SimH.  It may be better to use LAT between terminal servers and VMS running in the emulated VAX.
> 

That was the whole point of LAT. At the time almost all serial terminals were connected by DZ-style interfaces, so 1 interrupt when you typed a character and a second interrupt after the character was echoed. LAT created a virtual circuit between the terminal server and a specific host. The slot layer ran over the virtual circuit between a logical terminal on the host and a physical terminal on the server. Data messages at the virtual circuit layer were limited to no more frequent than a terminal server parameter ( default 80mS). With appropriate optimizations and data availability it was possible to shrink the interrupt load on the host to 1-2 interrupts/ethernet packet (say around 1400 characters). There were a lot of internal religious wars around the use of CTERM/Telnet/LAT.

After finishing DECnet-Ultrix I had a couple of weeks of spare time and implemented a prototype Ultrix-LAT - one of the good things that came out of having a MicroVAX I in my office!

  John.

>> How long was the VAX timesharing era as I suspect networked PC's come out soon after that.
> 
> Good question.
> 
> 
> 
> -- 
> Grant. . . .
> unix || die