Classic Computer Magazine Archive CREATIVE COMPUTING VOL. 9, NO. 6 / JUNE 1983 / PAGE 177

A letter quality alternative for Atari users. Nancy Blumenstalk Mingus.

A Letter Quality Alternative For Atari Users

You want letter quality capabilities on your Atari system, but Atari makes only dot matrix printers. So you decide to wait until they produce a letter quality printer instead of fighting with interfacing to non-Atari printers right? Well, you don't really have to wait. By using the Atari 850 interface module you can use any parallel printer or RS-232 serial printer on the market.

But, be forewarned. Interfacing other products to the Atari is not as easy as Atari would lead you to believe. I found this out the hard way. Although Atari does give you all the information necessary to use the interface module properly, you must glean the facts from three different manuals. This article explains some of the problems encountered in interfacing an Anderson Jacobson 832 (RS-232) to the Atari, and offers some solutions that should apply to many other RS-232 printers as well.

One of the first problems faced by any new printer owner is getting a cable to connect the computer to the printer. I was no exception. Although the literature on the 850 says it is standard RS-232, it has only 9-pin connectors. Most printers use 25-pin connectors so you need a cable to convert the signals coming from the 25-pin connector into signals recognized by the 9-pin connector.

Now I am not an electronics expert, so I wouldn't even attempt to create my own cable. Since I use port 1 on the 850 for a modem, I wanted port 2 to be my printer port. With the wiring diagram for port 2 and he wiring diagram for the Anderson Jacobson printer in hand, I located a good electrician and he kindly wired everything correctly for me. If you don't know anyone in your area who does this king of work, your local Atari dealer should be able to help you.

Once everything is connected properly, there are a few other things you need to remember when using the printer. The most important of these concerns the disk drive. If you plan to use a disk drive with your interface module and printer you must have DOS II as your disk operating system.

There is a special file in DOS II called AUTORUN.SYS which automatically runs when you turn on the computer. This affects the power up sequence you use. You must first turn on the printer, then the disk drive, then the interface module, and finally the computer. Also, be sure you have the Basic ROM pac in place.

Most of the above is explained in the 850 manual, but they make no mention of the AUTORUN.SYS file. The problem I encountered was error number 130 when I tried to open the printer port. This message indicates that the interface module can find no such device. What had happened was that the system disk I had created from the master disk had not copied the AUTORUN.SYS file. Once I copied the file on to the system diskette, I could then open the printer port.

Trying to print or list on the printer is now a fairly simple matter. To print to it, I just type:

OPEN #2, 8, 0, "R2:'


OPEN signifies initialization of a device or file.

#2 indicates the channel number being used. It can be any number 1 through 8.

8 means opening the channel for output only, which is all that is required for a printer.

0 this argument is not used, so will always be zero.

"R2:' refers to the port being used. The 2 signifies port 2.

Any subsequent printing statement takes the following form:

PRINT #2; "Anything', variable


PRINT is the standard Basic PRINT command.

#2 is the channel previously defined in an OPEN.

To close the device or file, you enter:



CLOSE means you are terminating the use of a channel.

#2 is the channel being closed.

Again, this is explained fairly well in the interface module manual. The LIST command however, is somewhat confusing. To LIST to the printer, instead of LIST #2 as you might expect, you must type:



LIST functions the same as usual.

"R2' is the port number you are listing through.

Now that you know how to connect your printer, list a program, and print lines to the printer you are almost ready to start. There is however, one last problem. The default configurations of the RS-232 ports as shown in the 850 manual need one modification because the ports do not send a linefeed when they send a carriage return. That is, when the printhead returns to the left margin of the paper, the paper does not roll up one line. So all your lines print on top of each other. To change this, you must reconfigure one aspect of the printer port with which you are working. Again, I use port 2, and the command I use is:

XIO 38, #2, 64, 0, "R2:'


XIO is a special command used to configure various aspects of a port.

38 is the particular XIO command type.

#2 is the channel number being used.

64 is a decimal code meaning turn on linefeed.

0 as in the OPEN command, remains zero.

"R2' is the printer port.

Before you can do a list, you must enter this command, and to be safe, you should include it in any program you write which requires more than one line to be printed on the printer.

Now you should be in fairly good shape to start using that nice letter quality printer.

Table: Atari to Anderson Jacobson Wiring Chart.

Photo: Pin functions of Serial Ports 2 and 3 in the 850 Interface Module (9-pin female connector).