Changes
The CPC [[Printer Port]] has only 7bit 7 bit data. Which is okay sufficient for english 7bit 7 bit ASCII character sets, but not enough for 8bit 8 bit character sets. Also, printing bitmap graphics usually requires 8bit 8 bit data (though usually can also print 7 pixels columns combined with a reduced line-feed rate). Amstrad's DMP1 works perfectly with 7bit7 bit, but Amstrad's later DMP2000/DMP2160 include a few functions that won't work on 7bit 7 bit ports - so even the official CPC printers aren't fully compatible with the CPC printer port.
== Internal 8bit 8 bit Printer Ports/Mods ==
=== Happy Computer 8bit 8 bit Printer Port upgrade (DIY) ===A good method to upgrade to full 8bit 8 bit has been described in the german magazine "[[Happy Computer (Schneider Sonderheft)]] 2/85 and 4/86":
* Disconnect the D7 pin from ground, and wire it to the [[8255|PIO]]s 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. In contrast, this DIY is supported by [[FutureOS]].
* For details see: [[Happy Computer 8bit Printer Mod]]
=== CPC Schneider International - 8bit 8 bit Printer Port Mod ===
DIY from [[CPC Schneider International]] (issue 12'85, page 64), this solution uses joystick port pin 8 (or (keyboard?) pin 2, unclear?).
* For details see: [[CPCI 8bit Printer Mod]]
=== PC Amstrad International - 8bit 8 bit Printer Port Mod ===
DIY from [[PC Amstrad International]] (issue 8/9'91, page 69-70), this solution uses PPI.Pin12 (same as the [[Happy Computer 8bit Printer Mod]]).
=== 8bit 8 bit Printer Port in KC Compact ===
The [[KC Compact]] uses the Bit5 of [[8255|PPI]] Port C as 8th printer bit (this is same as the Happy Computer mod, see above). Although the 8th bit is a built-in feature, the KC Compact BIOS doesn't support it. But it's supported by [[FutureOS]].
=== 8bit 8 bit 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. The BIOS functions are patched accordingly; including for supporting the 8th bit (unlike the CPC Plus and KC Compact, which do not support the 8th bit in BIOS functions).
=== 8bit 8 bit 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 10 kOhm resistor R30 on the mainboard (aka R130 in the schematic). See [[LK Links]] for more info. Although the 8th 8 th bit is a built-in feature, the CPC Plus BIOS doesn't support it. However the 8 bit printer port of the CPC Plus is supported by [[FutureOS]].
== External Printer Ports ==
* [[8bit Printer Port (Amstrad Action)]] (DIY) - connects to Expansion Port (uses Port FBF8h/FBF9h)
* [[8bit Printer Port (Paul Bauriedl)]] (DIY) - connects to Printer Port (splits port EFxxh to 2x4bit2 x 4 bit)* [[CPCI 8bit Printer Mod]] (DIY) - connects Bit7 bit 7 to Joystick_1_Select signal (can be connected internally or externally)
* [[CPCISA by Yarek]] can be used with various ISA bus printer cards (8bit, one- or bi-directional types, SPP, XPP, EPP, etc.)
* [[KDS 8-Bit Printer Port]] ([[KDS]] Electronics) - connects to Printer Port (splits port EFxxh to whatever fragments - details are unknown)
* [[Panda Electronics Communications Interface Unit]] (dual RS232 plus PPI-based 8bit printer port) (Panda Electronics Ltd)
* [[RS232|RS232 Interfaces]] (various manufacturers) - can be used to access RS232-compatible printers with full '''8bit8 bit''' support
Also, reportedly, the following external hardware exists:
* 8bit 8 bit Printer Port (Pride Utilities) ([[Pride Utilities 8bit Printer Port|details]])* 8bit 8 bit Printer Port with Dual RS232 ([[Timatic Systems]])* 8bit 8 bit Printer Port with 16bit 16 bit I/O port ([[HoneySoft]]) (see [[Media:Amstrad Computer User8509037.jpg|advert]])
There's nothing else known about that hardware.
