pport

THE PARALLEL PRINTER PORT

Although the Parallel Printer port was primarily intended for a CENTRONICS parallel printer, this port offered many more diverse interfaces such as two types of Joystick interfaces and a sound sampler.

Unlike modern Parallel ports, the ORIC has only the bare minimum of lines.

Pin	Lines	Details
	STROBE	Tells the printer that valid data is on the Data Lines
	Data	Full 8 bit Data lines
	ACK (Acknowledgement)	Tells the computer that the data lines have been read.
	Ground	The whole bottom row is Ground

Note the exclusion of any Power lines. This made it hard to use for any interfaces, since these would invariably require power. Never the less, interfaces did appear. One of the reasons for placing interfaces on this port was that no address decoding was required for small applications such as a Joystick interface.

Within ORIC memory, the Printer port appears at #030F and #0301. This is the 6522's Port A address space and also provides the same data lines to the AY-3-8912 Programmable Sound Generator (PSG). Fortunately, separate lines tell the PSG when valid data is on the Data lines (BUS).

There also exists a data direction register to change the direction of data on each bit of Port A. This appears at location #0303. A Bit set defines the data line as output, cleared and the data line becomes input only.

The STROBE handshake line appears as BIT 4 of port B (#0300) whilst the ACK line is input only and therefore can only be trapped (sensed through reading the interrupt flag of that bit in #030E).

PASE Joystick Interface	The PASE joystick Interface appeared on the market in 19??. It was the first Interface to utilise the Printer port as the means of joystick interfacing. The PASE interface allows two ATARI standard joysticks to be used. Many games support this interface.
Pro's Compatible with the majority of games that support joystick control. Very simple (In machine Code) to read each joystick.	Cons Tends to interfere with any audio output from the ORIC, since no discrimination is made between valid Joystick responses and Sound chip data. There is also no visual indication of which joystick port is A or B. Finally, the joystick does not support "Auto-fire" since no power can be drawn from the printer port for the oscillator circuit in the joystick.

IJK Joystick Interface	The IJK Joystick appeared on the Market in 19?? and was the second interface to utilise the Printer port as the means for Joystick interfacing. The IJK interface also allows two ATARI style joysticks to connect to it. It is supported by the majority of titles released by IJK Software that support Joystick compatibility.
Pro's By using the Strobe Pin on the Printer port, IJK managed to discriminate between Joystick data and Sound Data, therefore guaranteeing no interference with sound quality. Clearer identification of joystick A and Joystick B.	Cons More code required to read joystick. Although greatly Improved, Fewer games support this interface. Still does not support auto-fire facilities on joysticks.

The ORIC Sampler	This is the ORIC Sampler. Built in 1995 by Denis Bonfield, only two were ever made! Worth a mention only because, as far as i know, no other Sound Sampler Interface was ever built for the ORIC. It is based around an 8 Bit ADC, taking its power source from the ORICs own power plug, whilst a further lead supplies the ORIC from the board. The input requires a pre-amp in order to be driven from a microphone.