Earlier Atari Hardware Projects

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Printer Interface

Click for a larger imageBack in 1986 I constructed a SIO printer interface based around the National Semiconductor (who I worked for at the time) INS8048. This is a simple, old 8 bit microcontroller. The code was held in a 2kbyte EPROM. The device connected to the centronics parallel interface of a dot-matrix printer. I still have a printout of the 8048 assembler code. The code to interface to the SIO bus is remarkably simple. A DIP switch selects whether the Atari carriage return character is translated to the normal ASCII codes or not.


Click for a larger imageI made this project on the same piece of circuit board as the printer interface. I had mounted a second SIO connected with the original intention of allowing the printer interface to be part of a chain, but I never got around to wiring it up. So in the remaining free circuit board space I used a MAX232 chip to make the SIO to 1050 interface. The intention was to allow me to read my diskettes and store their images on the PC (and possibly use them with the Atari emulator). I had a play with the software and I was able to read Atari diskettes, however a problem was that I didn't know which density the disks were formatted in.


Click for a larger imageI have used the PIC16C84 in a number of projects. It occurred to me that it should be possible to interface a PIC to the SIO bus. I interfaced a 16 character LCD display to the PIC. This allowed the commands on the SIO bus to be displayed. I was interested to see just what special commands were been sent to my Happy 1050 drive. It wasn't too practical since there was too much data to display on such a small screen. With the addition of only an extra TTL chip I am sure that a modern printer interface could be constructed. If there is enough interest I will post schematics (not yet drawn) and source code on these web pages.

SIO-2-PIC schematic in PDF format (V1.0)
PIC assembly source code V1.02

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