            Parallel Data Transfer V2 If you can get the User Port to behave as if it were a printer then you have a simpler way of transporting data from any computer with a printer port to the beeb, i.e no baud rate etc. to worry about. This adaptor does just this, the program then saves the incoming data to a previously opened file when the tran- sfer is complete pressing ESCAPE closes the file. The printer side of this adaptor can either have a centronics socket into which the normal printer lead may be plugged or you could connect direct to the source computer. Adapter diagram ---------------  N/C   O X O O O O O O O N/C   O X O O O O O O O BUSY   O X O O O O O O O ACK    O X O O O O O O O bit 7    bit 7  O X O O O O X O  bit 6   bit 6  O X O O O O X O  0v bit 5   bit 5  O X O O O O X O  0v bit 4   bit 4  O X O O O O X O  0v bit 3   bit 3  O X O O O O X O  0v bit 2   bit 2  O X O O O O X O  0v bit 1   bit 1  O X O O O O X O  0v bit 0   bit 0  O X O O O O X O  0v STROBE    CB2  O X O O X O O X O  5v   CB1 O O O O O O O X O  5v Centronics User Port Side Side Track direction is across the screen. N/C not connected X indicates cut track. Both grounds need to be connected together to provide a common reference Function -------- When the BUSY signal is low 8 bit data comes in the centronics side, then the strobe pulse is sent which causes a CB1 interrupt, raising the BUSY signal. After dealing with the data, BUSY is again set low. Signals ------- STROBE.is sent by the computer when the data is valid.  ACK..is an output of the printer which tells the computer it has received the last character sent and is active low. BUSY.is an output of the printer which when high tells the computer not to send any more data. DATA  IN STROBE  IN ACK/BUSY  OUT The program ----------- There are two modes of operation :- Binary mode All data is passed and saved. Check for characters ignored, not sent to the printer by the transmitting computer. Ascii mode Character 10's (line feed) are not saved, this tidies documents from various machines as there is no standard set order of the line feed and carriage return that may mark the end of each line. Also there is a routine to ignore standard printer commands and some Epson commands, these can be tailored to individual needs. In this mode text is written to the screen (80 columns) so you can see what is being saved, this has the bonus of method of seeing a document before being printed saving valuable paper.            