¢HARDWARE WAREHOUSE¢¢A CHEAP HOME-MADE PRINTER INTERFACE¢¢by Alan Hitchen¢¢ If you want to use a printer not made by Atari you will need an adaptor to suit the standard Centronics parallel interface. The MicroPrint unit is currently available from Micro Discount at 28.00 pounds, plus 1.50 p&p. However a cheaper alternative is available if you have the ability to build it yourself.¢¢ Following the design of Len Golding, as published in the Atari User magazine of April 1987, a simple interface utilising the joystick ports can be constructed for about 12.00 pounds.¢¢ The items needed are two Joystick extention leads and a 36 way Centronics connector. The leads are available from Tandy as item 270-1705 at 3.99 each. If you have them, leads from broken joysticks could be used if the cable is okay.¢¢ Tandy do sell a connector, but it is an IDC type intended for ribbon cable. The correct solder type connector is available from Maplin as item FJ61R for 1.98, plus 1.50 p&p. ¢¢ First of all, cut off the extention lead sockets and prepare the cable ends for soldering. Check which lead connects to which pin with a continuity tester, or battery and bulb. Check both leads, as wire colours vary from cable to cable. Having done that, identify the leads as one and two, then solder the wires to the 36 way connector as follows.¢¢JOYSTICK PORT CENTRONICS¢¢1 2 3 4 5 18-------1¢¢ 6 7 8 9 36------19¢¢JOYSTICK PORT ONE TO CENTRONICS¢¢Pin 1 to Pin 2 Data 1¢Pin 2 to Pin 3 Data 2¢Pin 3 to Pin 4 Data 3¢Pin 4 to Pin 5 Data 4¢Pin 6 to Pin 11 Busy¢Pin 8 to Pin 16 Ground¢¢JOYSTICK PORT TWO TO CENTRONICS¢¢Pin 1 to Pin 6 Data 5¢Pin 2 to Pin 7 Data 6¢Pin 3 to Pin 8 Data 7¢Pin 4 to pin 1 Strobe¢Pin 6 to Pin 32 Fault¢Pin 8 to Pin 33 Ground¢¢ Finally link Centronics pin 9 (Data 8) to Pin 27 (Ground). Carefully tape up the unused wires. Remember that Joystick pin 7 carries +5v and should not be connected. Assemble the Centronics housing and the project is complete.¢¢ In order to use the interface, software is needed to divert the print data to the joystick ports. The software provided creates an autoboot program that inserts a new P: device into the the handler table to do this. Unfortunately this means that most commercial programs can't use this interface. ¢¢ However the program is reset proof, does not use Page 6 memory, and can handle all printer commands. It can be used by your own programs and others like VIEWDOCS.BAS. You could for example, write your text with any word processor, print the text to disk (or cassette), then boot the interface and VIEWDOCS to print it out.¢¢ The interface converts the Atari end of line code 155 into ASCII code 13. This will cause a carriage return but no line feed unless you enable the automatic feed option on your printer.¢¢ The interface cannot send ASCII codes 128 upwards, as the eighth bit is held low by the link to ground. This was done in order to use the eighth bit to operate the strobe, which signals data entry. This will prevent the use of some of the features of your printer, such as italics, special characters and graphics. ¢¢¢Maplin's 1995 catalogue is available from W.H.Smiths at 3.45, or 3.95 by post from.¢¢MAPLIN ELECTRONICS¢PO BOX 3¢RAYLEIGH¢ESSEX¢SS6 8LR¢¢Phone 0702 552911¢¢¢Tandy's Head Office is at.¢¢InterTAN U.K. Ltd.¢Tandy Centre¢Leamore Lane¢Walsall¢West Midlands¢WS2 7PS¢¢Phone 0922 710000¢
