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Last modified on 26 February 2010, at 08:27

8bit Printer Ports

Revision as of 08:27, 26 February 2010 by Nocash (Talk | contribs) (→‎External Printer Ports)

The CPC Printer Port has only 7bit data. Which is okay for english 7bit ASCII character sets, but not enough for 8bit character sets. Also, printing bitmap graphics usually requires 8bit data (though Amstrads own printers are probably working with 7bit).

Internal 8bit Printer Ports/Mods

Happy Computer 8bit Printer Port upgrade (DIY)

A good method to upgrade to full 8bit has been described in the german magazine "Happy Computer Sonderheft 4/86":

  • Disconnect the D7 pin from ground, and wire it to the PIOs Tape WR DATA pin instead (That is, Pin 12 of the 8255 chip).

Sharing that pin will cause no problems (as long as you do not attempt to send data to the tape drive and to printer at the same time). Of course, you will also have to customize your software, or BIOS ROM, or the BIOS jump vectors in RAM, in order to take advantage of the modification.

8bit Printer Port in KC Compact

The KC Compact uses the Bit5 of PPI Port C as 8th printer bit (this is same as the Happy Computer mod, see above).

8bit Printer Port in Aleste 520EX

The Aleste 520EX includes an 8bit printer port, using PSG Ext Port B for data (which does not exist on the CPC), and PPI port C, Bit 4 for strobe (which would be Tape Motor in CPC). The Aleste doesn't have the normal CPC-style Printer Port at Port EFXXh.

8bit Printer Port in CPC Plus

In the CPC Plus, Bit 3 of CRTC Register 0Ch can be used as eighth printer bit. For compatibility to normal CPCs, this feature can be disabled by removing the 10kOhm resistor R30 on the mainboard (aka R130 in the schematic). See LK Links for more info.

External Printer Ports

Amstrad Action Issue 38 - November 1988

Also, reportedly, the following hardware exists:

  • Communicator 104 (KDS Electronics) (1992) Reportedly: "Serial and Parallel interface" (or, actually, Mini-Max Modem)
  • 8bit Printer Port (KDS Electronics) (this may be same as above)
  • 8bit Printer Port (Pride Utilities) (details)
  • 8bit Printer Port with Dual RS232 (Timatic Systems)
  • CPCISA by Yarek can be used with various ISA bus printer cards (8bit, one- or bi-directional types, SPP, XPP, EPP, etc.)

There's nothing else known about that hardware.