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Rosanna Rosannadana would find this offensive ;-)
Scientific Approaches wrote:
> It seems impossible to say much of anything on this list without offending
> someone and becoming the target of public or private insults. However, I
> can't imagine who this will offend, so I will give it a try.
>
> A printer port security block usually does not interfere with the operation
> of a printer connected to the same port. Likewise, a printer usually does
> not interfere with the operation of a security block. However, in some
> cases either type of problem can occur.
>
> Security blocks, like modems, have two modes of operation. There is a
> normal mode where data is passed through. There also is a command mode
> where it is not.
>
> In the case of modems, the command mode is used to change communication
> protocols, baud rates, the number of start and stop bits, and other things.
> In the case of a security block, the command mode is used to activate a
> block and ask it to identify itself, and in the case of a sophisticated
> block, to ask it to encrypt or decrypt program files or data, or do other
> things. Both with modems and security blocks, special signals are used to
> switch between the normal and command modes. Both with modems and security
> blocks, other signals sometimes are mistaken for the correct ones. If a
> printer port security block mistakenly switches to command mode, it will
> assume information sent to a printer is for it, so it won't pass it through
> to a printer.
>
> The signal mix-up most often occurs when a computer first boots. When
> computers boot, the BIOS (Basic Input Output System) sends reset commands to
> each serial and parallel data port to clear any error conditions and to
> ready them for normal operation. That should cause no security block
> problems, but some computer parallel port hardware sends a signal when it is
> reset that is interpreted by security blocks as a signal to switch to
> command mode. If that happens, a security block will "eat" everything sent
> to a printer port afterward, so a printer connected to the same port will
> receive nothing.
>
> There are several solutions. Installing a different parallel port card in a
> computer usually will correct that problem. Replacement parallel cards are
> widely available for $10 to $20. They usually are easy to install.
>
> Printer port security block manufacturers are continually designing-in new
> filters to trap the invalid signals sent when some computers boot. If an
> Omega security block doesn't work correctly with a printer on your computer,
> Omega might be willing to exchange your block for a newer one that will work
> with the computer parallel port hardware you already have. I have no idea
> whether they will be willing to do that. I am only suggesting a solution
> that likely would solve the problem.
>
> The second type of problem is where a printer interferes with the operation
> of a printer port security block. That problem is rare, although many
> complain of it where the problem actually is the problem described above.
> It doesn't occur with most printers, but there are a few printers on the
> market that short parallel printer port data lines to ground when they are
> switched off. A printer that does that will short-circuit communication
> between a computer and a security block whenever the printer power is
> switched off.
>
> That problem is more difficult to overcome. The leading security block
> manufacturers supply blocks that will work with those printers. The only
> other easy fix is to disconnect the printer data cable from the security
> block when the printer power is off.
>
> -Bob Brickey
> Scientific Approaches
> sci@xxxxxxxxxx
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