Technical data

16
BUS_PORT
The BUS_PORT supports off-board parallel devices. Power (+5V), ground, address lines, data
lines, and control lines are brought out to this 34 pin connector. Pin assignments are as follows:
PIN BUS_PORT PIN
GND 1  { 2 D3
D2 3 { { 4 D4
D1 5 { { 6D5
D0 7 { { 8D6
A0 9 { { 10 D7
A1 11 { { 12 A2
A10 13 { { 14 A3
OE 15 { { 16 A4
A11 17 { { 18 A5
A9 19 { { 20 A6
A8 21 { { 22 A7
A12 23 { { 24 A13
W/R 25 { { 26 CS0
CS1 27 { { 28 CS2
CS3 29 { { 30 CS4
CS5 31 { { 32 IRQ
+5 33 { { 34 M2
A/D REFERENCE
The VRH and VRL lines from the HC11 are connected to +5v through R3 and to ground through
R2 respectively. These two resistors are located next to the MCU_PORT header. The resistors
are identified on the silk screen by their reference designators. The appropriate resistor(s) need to
be removed in order to apply an external reference to the VRH and/or VRL inputs.