8048/8049 to Polysix MIDI board connection by wire # ---------------------------------------------------- (c) Copyright 1997 Ricard Wolf 8048 socket Wire Pin# Chip function pin 1 40 - +5V power - 2 1 8255-I PB6 24 3 39 8255-I PB7 25 4 2 - - - 5 38 8255-I PC7 10 6 3 - - - 7 37 8255-I PC6 11 8 4 - RESET* - see netlist 9 36 8255-I PC5 12 10 5 +5V power 11 35 8255-I PC4 13 12 6 8255-I PB4 22 13 34 - GND - 14 7 - GND power - 15 33 8255-II PC6 11 (note other 8255!) 16 8 - +5V - 17 32 - - - 18 9 - - - 19 31 - - - 20 10 - +5V - 21 30 8255-I PB3 21 22 11 - +5V - 23 29 8255-I PB2 20 24 12 8255-I PA0 4 25 28 8255-I PB1 19 26 13 8255-I PA1 3 27 27 8255-I PB0 18 28 14 8255-I PA2 2 29 26 - +5V power - 30 15 8255-I PA3 1 31 25 - - - 32 16 8255eI PA4 40 33 24 8255-I PC3 17 34 17 8255-I PA5 39 35 23 8255-I PC2 16 36 18 8255-I PA6 38 37 22 8255-I PC1 15 38 19 8255-I PA7 37 39 21 8255-I PC0 14 40 20 - GND power - 8049 socket Wire Pin# Chip function pin 1 40 - - - 2 1 - - - 3 39 - - - 4 2 - - - 5 38 8255-II PC7 10 6 3 - - - 7 37 - - - 8 4 - - - 9 36 8255-II PC5 12 10 5 - - - 11 35 8255-II PC4 13 12 6 8255-I PB5 23 (note other 8255!) 13 34 8255-II PB7 25 14 7 - - - 15 33 8255-II PB6 24 16 8 - - - 17 32 8255-II PB5 23 18 9 - - - 19 31 8255-II PB4 22 20 10 - - - 21 30 8255-II PB3 21 22 11 - - - 23 29 8255-II PB2 20 24 12 8255-II PA0 4 25 28 8255-II PB1 19 26 13 8255-II PA1 3 27 27 8255-II PB0 18 28 14 8255-II PA2 2 29 26 - - - 30 15 8255-II PA3 1 31 25 - - - 32 16 8255-II PA4 40 33 24 8255-II PC3 17 34 17 8255-II PA5 39 35 23 8255-II PC2 16 36 18 8255-II PA6 38 37 22 8255-II PC1 15 38 19 8255-II PA7 37 39 21 8255-II PC0 14 40 20 - - - Notes: 1. Power is supplied to the MIDI board solely from the 8048 socket, using the lines marked "+5 power" and "GND power". The lines marked "+5V" and "GND" do not supply power, but should be grouped with the respective power line anyway. All power lines enter the MIDI board at ONE point, where the 220 uF capacitor is located. 2. 8048 pin 4 supplies the RESET* signal to the MIDI board. 3. Most 8048 signals go to the 8255-I and most 8049 signals go to the 8255-II. However, note that there are two signals which go to the 'other' 8255. 4. All PB and PC lines on both 8255 chips have 4k7 pullups to +5V on the MIDI board, utilizing resistor networks. 5. Pin one of both wires has a coloured stripe.