[Info-vax] Gartner report on VMS future.

[Allen, Daniel P.]

-----Original Message-----
From: info-vax-bounces at rbnsn.com [mailto:info-vax-bounces at rbnsn.com] On Behalf Of Richard B. Gilbert
Sent: Monday, September 21, 2009 3:24 PM
To: info-vax at rbnsn.com
Subject: Re: [Info-vax] Gartner report on VMS future.

>>
>> ASTs and interrupts are about as similar as knives and screwdrivers.
>> You don't really want to use one where you really wanted the other one.

>An AST is an interrupt, delivered at a priority of ASTDEL.  I don't
>recall the numerical value of ASTDEL and I'm too lazy to look it up.

ASTDEL = 2

AST = Asynchronous System Trap - an asynchronous software (OS scheduled) switch of the execution path in your code as opposed to a hardware interrupt. It occurs at a slightly elevated priority well below hardware interrupt level and requires a return to the non-AST code path via the OS dispatcher (REI in VAX speak).

Dan