Research Machines User I/O Cable USER I/O CABLE INSTRUCTIONS The User I/O cable has been designed to connect the 20 way user port socket on the CPU board to a 25 way sub-min 'D' type connector which can be mounted through the rear panel of the 380Z case. These instructions will help you install the cable correctly into your 380Z. 1. Remove the lid of the 380Z's case. This is done by removing the two screws from the top rear section of the lid, and then lifting the lid upward from the back. The computer must be isolated from the mains before the lid is removed. 2. Remove a suitable blanking panel from the rear of the case and attach the 25 way 'D' socket using the screws provided. 3. Now plug the 20 way connector into the user I/O port on the rear of the CPU board. The edge of the flat cable with the brown or coloured line on must point to the edge of the CPU board. Failure to do this will result in damage. 4. Replace the lid of the case, switch on the computer and attach the printer, via a suitable cable, to the 25 way user I/O connector on the-rear of the case. Testing To test the parallel port, first select it using the front panel, it is line- printer option 3. Then if your computer is of COS 3.0 type, type CTRL T and everything typed on the keyboard will be sent to the parallel port (i.e. it will echo the keyboard to the printer). If, however, your computer is of COS 2.3 type, you will have to select the printer options as above and then enter this simple machine code routine using the front panel: Location Code Comments 4200 F702 Scan keyboard 4202 28FC Jump back if no character 4204 F705 Write character to printer 4206 C30042 Jump back to start To start this program jump to 4200 hex. It will echo everything typed on the keyboard to the printer. IPN 02108101 January 1981 Page 1 of 2 Technical Research Machines User I/O Cable 380Z USER I/O CONNECTIONS CPU BOARD REAR PANEL 380Z 20-Way 25-Way 'D' Sub. Min. Socket PIN SIGNAL PIN SIGNAL 1 D0 IN 1 Busy 2 D1 IN 14 Fault Input (N) 3 D2 IN 2 4 D3 IN 15 5 D4 IN 3 6 D5 IN 16 7 D6 IN 4 8 D7 IN 17 9 D0 OUT 5 Data Bit 1 (LSB) 10 D1 OUT 18 Data Bit 2 11 D2 OUT 6 Data Bit 3 12 D3 OUT 19 Data Bit 4 13 D4 OUT 7 Data Bit 5 14 D5 OUT 20 Data Bit 6 15 D6 OUT 8 Data Bit 7 (MSB) 16 D7 OUT 21 Data Strobe (N) 17 + 5V 9 18 -12V 22 19 +12V 10 20 0V 23 Circuit Common (Ground) Active low signals are specified by the notation (N) after the signal name. LSB = Least Significant Bit MSB = Most Significant Bit User I/O Input is to a 74LS244 which requires standard TTL Input voltages. High Level Input Voltage Min. 2V Low Level Input Voltage Max. 0.8V High Level Input Current 20uA to 2.7V Low Level Input Current -200uA at 0.4V Output device is 74LS374: High Level Output Voltage Min. 2.4V at I = -15mA OH Low Level Output Voltage Max. 0.4V at I = 12mA OL The user I/O port may be used to drive Centronics compatible printers. The signal names are given in Column 4. IPN 02108101 January 1981 Page 2 of 2 Technical