The programming to respond to either a MODIFY command or a WTOR reply is
pretty simple. From my POV the level of complexity is similar. In either
case, to ensure that operator input is recognized and processed
promptly, it is advisable to create a separate TCB to handle the
operator input.
Regarding the use of a START command to cause another started task to
stop, the saying "if all you have is a hammer, everything looks like a
nail" comes to mind.
Think back to the complaints when Windows first came up with the "Start"
button..."What, I have to click Start to stop my computer?"
--
Regards, Gord Tomlin
Action Software International
(a division of Mazda Computer Corporation)
Tel: (905) 470-7113, Fax: (905) 470-6507
On 2012-12-05 14:35, McKown, John wrote:
Well, I know for a fact that some vendors still don't use MODIFY commands for their
products. They "hang" a WTOR. Why? I guess it's just easier.
I spoke with my manager, who used to work for a vendor. He said that for one product he knew of,
what became an independent STC was once a subset of a larger STC. If you wanted to shutdown that
particular subset, it was easier to issue a START which ran a program which connected to the
subfunction and said "shut down". Use of a MODIFY would have caused contention with the
routines in the enclosing STC. Since then, the subset was moved into a separate STC, but originally
"as is", thus continuing to use the second START. Since then, they have upgraded the
separated code to use a STOP as well, but left in the old shutdown code in for existing users.
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