Unusual Omnitronix Interface

[Andrew Wiskow]

I'm hoping that someone here might be able to help me out...  I came across what may possibly be the "first edition" of the Omnitronix Deluxe RS-232 Interface.  Up until now, all of the Omnitronix interfaces I've seen have looked like this:

http://tinyurl.com/34y5zv

As you can see, this says "Deluxe RS-232 Interface" on the top, "Omnitronix" on the bottom, and three up/down switches labeled "Modem1/Printer1", "Modem2/Printer2", and "Normal/Inverted".  I've also seen a model that only had two of these three switches, but was otherwise identical.  According to a post by Jim Brain on the comp.sys.cbm newsgroup over a year ago, the three switches on this interface function as follows:

M/P1 switches from DTR/DSR signaling to CST/RTS signalling
M/P2 hooks CTS to RTS on same side (nulling them out)
Normal/Inverted inverts DTR/DSR.

Now...  This apparently older model has an Omnitronix logo across the top, and reads "VIC-20/C64 Deluxe RS-232 Interface" on the bottom.  It also has three switches, but they switch from side-to-side instead of up and down, and they're labeled "Lo Busy/Busy Hi", "20 HSK/HSK 5", and "DCE/DTE".  Here are three photos of this interface:

http://tinyurl.com/2mnrvl
http://tinyurl.com/389je9
http://tinyurl.com/3djlnf

The first is the interface with its normal casing.  The second is the top side of the board without the casing.  And the third is the bottom side of the board without the casing.  It's not quite visable in the photo, but on the bottom side of the board, the following is etched in: "Omnitronix, Inc. DELUXE RS232 INTERFACE (c) 1984"

Has anyone seen one of these before, and does anyone have any idea what these switches do?  At first, I didn't think that this interface was working at all, but after playing with it a bit, I did get it to work on my BBS with the second switch set to "HSK 5".  However, at 2400 baud, a lot of charachters are garbled when calling in to the BBS (much like some older terminal programs for the C64 that claimed to support 2400 baud but really didn't), so either it doesn't function well at 2400 baud (I haven't tried it at 300 or 1200 yet), or there is some other problem.

I'd appreciate any insight that anyone here may have as to the use and functionality of this interface.  Thanks!

-Andrew

[Mangelore]

Howdy,

The BUSY signal is used for handshaking purposes to control the flow of data between a printer and a computer.

So, I guess the LO BUSY and BUSY HI switch simply inverts the BUSY signal (BUSY when either +5Volts or 0Volts). Might be required with different model printers or printer drivers.

The DTE/DCE switch would place the C64 in either DTE or DCE mode. When using a modem the 64 should be in DTE mode and the modem in DCE mode. However, some printers or devices may be configured in DTE mode so you'd need to use a null modem cable or switch the C64 to DCE mode.

Not sure what the 20 HSK / HSK 5 switch does, but it sounds like it has something to do with handshaking.  

Cheers
Fotios

[Andrew Wiskow]

Somone was kind enough to send me a scanned copy of the manual for this early release of the Omnitronix RS-232 Interface.  For anyone who cares, here is the information in the manual pertaining to the switches:

WHAT ARE THE SWITCHES ON THE RS232 FOR?

The Omnitronix Deluxe RS232 Interface has three switches on the top of the case.  These switches allow you to set up the RS232 Interface for using a printer or a modem.  The first switch is marked DTE/DCE.  This switch sets up the pin output for DCE or DTE as shown in the chart above.  Setting the switch on DTE makes pin 2 Transmit and pin 3 Receive.  Setting the switch on DCE makes pin 3 Transmit and pin 2 Receive.  If you have a modem, you want the first switch set on DTE.  If you have a printer, you want the first switch set on DCE.  Remember, whenever you are connecting two RS232 devices together, one should be DTE and the other should be DCE.

The second switch is marked 20 HSK/HSK 5.  This switch would only be important if you are using a printer.  If you are using a modem, set this switch to HSK5.  If you are using a printer, see the later section on PRINTER HANDSHAKING for this switch setting.

The third switch is marked LO BUSY/BUSY HI.  This switch would also only be important if you are using a printer.  If you are using a modem, set this switch to BUSY HI.  If you are using a printer, see the later section on PRINTER HANDSHAKING for this switch setting.

Interesting that they list the order of switches from bottom to top.  But, based on this, I now know that with a modem (or in my case, an "emulated modem" - aka BBS Server), I should have the switches set for DTE, HSK 5, and BUSY HI.  Or, all switches to the RIGHT.  

-Andrew