CPCI 8bit Printer Mod

An 8bit Printer Port DIY extension from German magazine CPC Schneider International (issue 12'85, page 64). Connects Printer Bit7 to Joystick 1 Select signal (joystick port pin8).

This solution isn't too recommended. Some drawbacks and problems are:

• Joystick Select is an open-collector output, so HIGH levels may be unstable (this could be fixed by an additional pull-up resistor).
• Bit7 may tend to be HIGH by default, so printing normal text won't work with normal software that doesn't support the mod (the schematic includes a switch to disable the mod manually).

The circuit can be connected internally to the mainboard, or externally to the joystick/printer port connectors.

Original Article

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Note

Some years later the same magazine (renamed to PC Amstrad International, issue 8/9'91, page 69) released another 8bit printer mod: This newer (and better) solution uses PPI.Pin12 (same as the Happy Computer 8bit Printer Mod).