-=> Steven Horn said to Greg Mayman
 -=> about "APPOSITE" on 05-07-03  22:09.....

 GM> Absolutely nothing until there is a disk read or write or a new ap
 GM> is started up. I don't consider that as "stealing cycles" either.

 SH> So why have it installed if it does absolutely nothing?

...UNTIL THERE IS A DISK READ OR WRITE OR A NEW AP IS STARTED UP!

For offline work, this is all that is necessary. Once the
software has been checked and found free of infection, and is
running in memory, there is ZERO chance of a virus spontaneously
appearing and infecting anything.

It's not like the smoke detector or the burglar alarm in your
house that has to be continually monitoring everything that is
going on.

It is much more like the airport security check that can ignore a
passenger once he has been screened.

When there are no people going through the gateway, the personel
are not checking anyone. THEY ARE DOING NOTHING! You might as
well ask what use are they if they do absolutely nothing!

 SH> So you load a program which stays in memory and monitors activity.  Is
 SH> that not a background task which runs continuously?

Nope, I load a lot of TSR which are not running continuously but
are only called up when I need them.

The ThunderByte TSR stays in memory and is used as an ALTERNATIVE
EXECUTION ROUTE to the disk read/write and the the part of the
DOS that puts EXE and COM files into execution.

When the TSR checked a file or an ap to make sure it is not
infected, there is no need to keep checking it. When there are no
disk read/writes there is no need to check whether they are being
done illegally by a virus.

As I said there is no need for it to run continuously.

 GM> Normally this causes the foreground task to slow down unless it has
 GM> a lot of redundant time waiting for keyboard or other input.

 SH> And what value does that have?  Is it intended to be some sort of task
 SH> balancer?

If the foreground task is waiting for an input, you can't slow it
down any more whether there is cycle stealing going on or not.

But when the computer is doing some heavy processing such as file
converting, sorting, or calculations, then cycle stealing will
slow it down a lot.

Cycle stealing is a BAD thing unless you have time to waste, like
when the comp is waiting for an input.

When you want cycle stealing to take place, such as when you need
two or more tasks to run at the same time, you have to give them
priorities. The one with the highest priority will steal cycles
from those with lower priorities, sometimes causing them to
freeze for considerable periods of time.

If virus checking really was needed to be running all the time,
it would have to be at the highest priority and would be stealing
cycles from the other tasks all the time.

As I said, with my comparatively slow computer, this would be
very obvious, and it DOES NOT HAPPEN.

 SH> But the analogy does not work, cycles are stolen while the program is
 SH> waiting for something.

Stolen? By what? If the program is waiting, cycles are WASTED.
There is nothing else that comes in and steals time, unless you
are running a lower priority background task.
                                                    
 SH> But why does it do this?  What is the ptogram intended to do?

Briefly ThunderByte virus monitor TSR is intended to check every
file being loaded from a HDD or FDD for the presence of hidden
viruses. AFAIK downloaded files are checked in a similar way when
you are online.

It also reroutes any disk writes so that it can check that they
are not being caused by a virus that has sneaked through the
defences. Possibly it may do the same for file uploads.

There is no need for it to be running continuously while the
computer is doing tasks that are related to memory operations
only.

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... Our true worth is the amount of good we do in this world.
___ Blue Wave/386 v2.30

--- FLAME v2.0/b