[Info-vax] VMS Software Partners with Stark Gaming to Create Revolutionary Online Gaming and eSport Server Infrastructure

[Bob Gezelter]

On Friday, August 7, 2015 at 12:27:10 PM UTC-4, Richard Maher wrote:
> On 8/7/2015 6:49 PM, Johnny Billquist wrote:
> 
> > Or are we not talking about the general AST thing that you have for user
> > programs?
> >
> 
> "User programs" ? Well yes; and Kernel, Exec, and Supervisor programs. 
> And the inner modes interrupting the outer modes.
> 
> As someone who struggled to draw an analogy to the crappy Javascript 
> event loop/queue I'm not keen of software spawned events.

Richard,

Software-spawned events are integral to all modern systems. Hardware events only have meaning for the lowest-level hardware drivers. The "timer" events one sees at user level are totally software constructs.

ASTs no later than RSX-11. The VAX architecture had special provisions to aid in the efficient dispatching of ASTs.

The Javascript event model can be confusing, not the least because, as I recall, it does not preclude preemption. ASTs by contrast, are FIFO by access mode (Inner mode ASTs can preempt outer mode ASTs within a process. A Kernel AST preempts an active User mode AST; a second User mode AST within the same process must await its turn.)

I covered this extensively in my various DECUS AST sessions on both AST programming and AST internals.

- Bob Gezelter, http://www.rlgsc.com