Introduction

The multiple 8255 I/O card is programmable peripheral interface for PC/XT, PC/AT or compatibles. The interface card provides 192 parallel input output interface for PC/XT, PC/AT or compatibles. The interface card provides 192 parallel input output (PIO) programmable line, and six independent 16 bits counter/clock.

The features of the Multi-8255 adapter are:

*Programmable I/O control functions.

*Up to 192 parallel I/O lines.

*Maximum of 2.35MHZ count rate.

*Six independent 16 bits counters.

*Support several operating modes, which are programmable.

*Port address selectable.

HARDWARE CONFIGURATION

2.1 Configuration for jumpers setting

Before you use the multi-8255 I/O card, you must ensure that the I/O address and the clock are set correctly. Observe the figure bellows the proper settings for the multi-8255 I/O card are described in the following:














SYSTEM REQUIREMENTS

1. I/O Address

The JP1 is used to select I/O port address, the address mapping of 8255 chips and 8253 chips are shown in the followings:

Address Mapping

Chip No.
JP1 short JP1 open
8255 (1) 280-283 300-303
8255 (2) 284-287 304-307
8255 (3) 288-28B 308-30B
8255 (4) 28C-28F 30C-30F
8255 (5) 290-293 310-313
8255 (6) 294-297 314-317
8255 (7) 298-29B 318-31B
8255 (8) 29C-29F 31C-31F
8255 (1) 2A0-2A3 320-323
8255 (2) 2A8-2AB 328-32B

 

JP1: Open

 











Select &H300 - &H32B as I/O port address. The I/O functions are shown in the following:

&H300: Port 1A input/output buffer.

&H301: Port 1B input/output buffer.

&H302: Port 1C input/output buffer.

&H303: Port 1 control register.

&H304: Port 2A input/output buffer.

&H305: Port 2B input/output buffer.

&H306: Port 2C input/output buffer.

&H307: Port 2 input/output buffer.

&H308: Port 3A input/output buffer.

&H309: Port 3B input/output buffer.

&H30A: Port 3C input/output buffer.

&H30B: Port 3 control register.

&H30C: Port 4A input/output buffer.

&H30D: Port 4B input/output buffer.

&H30E: Port 4C input/output buffer.

&H30F: Port 4 control register.

&H310: Port 5A input/output buffer.

&H311: Port 5B input/output buffer.

&H312: Port 5C input/output buffer.

&H313: Port 5 control register.

&H314: Port 6A input/output buffer.

&H315: Port 6B input/output buffer.

&H316: Port 6C input/output buffer.

&H317: Port 6 control register.

&H318: Port 7A input/output buffer.

&H319: Port 7B input/output buffer.

&H31A: Port 7C input/ output buffer.

&H31B: Port 7 control register.

&H31C: Port 8A input/output buffer.

&H31D: Port 8B input/output buffer.

&H31E: Port 8C input/output buffer.

&H31F: Port 8 control register.

&H320: Counter 1A input/output buffer.

&H321: Counter 1B input/output buffer.

&H322: Counter 1C input/output buffer.

&H323: Counter 1 control register.

&H328: Counter 2A input/output buffer.

&H329: Counter 2B input/output buffer.

&H32A: Counter 2C input/output buffer.

&H32B: Counter 2 control register.

&H308: Port 3A input/output buffer.

&H309: Port 3B input/output buffer.

&H30A: Port 3C input/output buffer.










JP1: Close (Default)
















Select &H280 - &H2AB as I/O port address. The I/O functions are shown in the followings:

&H280: Port 1A input/output buffer.

&H281: Port 1B input/output buffer.

&H282: Port 1C input/output buffer.

&H283: Port 1 control register.

&H284: Port 2A input/output buffer.

&H285: Port 2B input/output buffer.

&H286: Port 2C input/output buffer.

&H287: Port 2 control register.

&H288: Port 3A input/output buffer.

&H289: Port 3B input/output buffer.

&H28B: Port 3 control register.

&H28C: Port 4A input/output buffer.

&H28D: Port 4B input/output buffer.

&H28E: Port 4C input/output buffer.

&H28F: Port 4 control register.

&H290: Port 5A input/output buffer.

&H291: Port 5B input/output buffer.

&H292: Port 5C input/output buffer.

&H293: Port 5 control register.

&H294: Port 6A input/output buffer.

&H295: Port 6B input/output buffer.

&H296: Port 6C input/output buffer.

&H297: Port 6 control register.

&H298: Port 7A input/output buffer.

&H299: Port 7B input/output buffer.

&H29A: Port 7C input/output buffer.

&H29B: Port 7 control register.

&H29C: Port 8A input/output buffer.

&H29D: Port 8B input/output buffer.

&H29E: Port 8C input/output buffer.

&H29F: Port 8 control register.

&H2A0: Counter 1A input/output buffer.

&H2A1: Counter 1B input/output buffer.

&H2A2: Counter 1C input/output buffer.

&H2A3: Counter 1 control register.

&H2A8: Counter 2A input/output buffer.

&H2A9: Counter 2B input/output buffer.

&H2AA: Counter 2C input/output buffer.

&H2AB: Counter 2 control register.

2. Clock Selection





JP2: JP2 is used to select clock of 8253 (1).













JP2-1 = Short (default):

Select internal clock to counter 1A

JP2-2 = Short (default):

Select internal clock to counter 1B.

JP2-3 = Short (default):

Select internal clock to counter 1C.

JP2-1 = Open:

Select external clock to counter 1A.

JP2-2 = Open:

Select external clock to counter 1B.

JP2-3 = Open:

Select external clock to counter 1C.












JP3: JP3 is used to select clock of 8253 (2).













JP2-1 = Short (default):

Select internal clock to counter 2A.

JP2-2 = Short (default):

Select internal clock to counter 2B.

JP2-3 = Short (default):

Select internal clock to counter 2C.

JP2-1 = Open:

Select external clock to counter 2A.

JP2-2 = Open:

Select external clock to counter 2B.

JP2-3 = Open:

Select external clock to counter 2C.

2.2 Hardware Installation

Your multi-8255 I/O card is designed to be inserted in any available slot in your PC/XT, PC/AT, or compatibles. In order to gain access to the expansion slots and the programs switches on the main board, follow the steps listed below:

1. Set the multi-8255 I/O card switch.

2. Turn off all power of your computer and all peripheral devices before installing your multi-8255 I/O card.

3. Remove the cover of the computer.

4. Insert your reconfigured card into any available slot. Make sure your I/O card is firmly seated in the chosen slot.

5. Replace the cover of the computer.

6. You are now ready to use your multi-8255 I/O card for several applications.

2.3 Pin Assignment

There are four 50 pins I/O connectors, where CN1, CN2, CN3, CN4 corresponds to 8255 I/O ports, and CN5 corresponds to 8253 counter.






CONNECTOR CN1: 8255 (U6) and 8255 (U7)

PIN 1 1PA0 PIN 26 GND
2 1PA1 27 2PA0
3 1PA2 28 2PA1
4 1PA3 29 2PA2
5 1PA4 30 2PA3
6 1PA5 31 2PA4
7 1PA6 32 2PA5
8 1PA7 33 2PA6
9 1PB0
34 2PA7
10 1PB1
35 2PB0
11 1PB2
36 2PB1
12 1PB3
37 2PB2
13 1PB4
38 2PB3
14 1PB5
39 2PB4
15 1PB6
40 2PB5
16 1PB7
41 2PB6
17 1PC0 42 2PB7
18 1PC1 43 2PC0
19 1PC2 44 2PC1
20 1PC3 45 2PC2
21 1PC4 46 2PB3
22 1PC5 47 2PB4
23 1PC6 48 2PC5
24 1PC7 49 2PC6
25 GND 50 2PC7

 




CONNECTOR CN2: 8255 (U8) and 8255 (U9)

 

PIN 1 3PA0 PIN 26 GND
2 3PA1 27 4PA0
3 3PA2 28 4PA1
4 3PA3 29 4PA2
5 3PA4 30 4PA3
6 3PA5 31 4PA4
7 3PA6 32 4PA5
8 3PA7 33 4PA6
9 3PB0
34 4PA7
10 3PB1
35 4PB0
11 3PB2
36 4PB1
12 3PB3
37 4PB2
13 3PB4
38 4PB3
14 3PB5
39 4PB4
15 3PB6
40 4PB5
16 3PB7
41 4PB6
17 3PC0 42 4PB7
18 3PC1 43 4PC0
19 3PC2 44 4PC1
20 3PC3 45 4PC2
21 3PC4 46 4PB3
22 3PC5 47 4PB4
23 3PC6 48 4PC5
24 3PC7 49 4PC6
25 GND 50 4PC7

CONNECTOR CN3: 8255 (U1) and 8255 (U2)

PIN 1 5PA0 PIN 26 GND
2 5PA1 27 6PA0
3 5PA2 28 6PA1
4 5PA3 29 6PA2
5 5PA4 30 6PA3
6 5PA5 31 6PA4
7 5PA6 32 6PA5
8 5PA7 33 6PA6
9 5PB0
34 6PA7
10 5PB1
35 6PB0
11 5PB2
36 6PB1
12 5PB3
37 6PB2
13 5PB4
38 6PB3
14 5PB5
39 6PB4
15 5PB6
40 6PB5
16 5PB7
41 6PB6
17 5PC0 42 6PB7
18 5PC1 43 6PC0
19 5PC2 44 6PC1
20 5PC3 45 6PC2
21 5PC4 46 6PB3
22 5PC5 47 6PB4
23 5PC6 48 6PC5
24 5PC7 49 6PC6
25 GND 50 6PC7

CONNECTOR CN4: 8255 (U3) and 8255 (U4 )

PIN 1 7PA0 PIN 26 GND
2 7PA1 27 8PA0
3 7PA2 28 8PA1
4 7PA3 29 8PA2
5 7PA4 30 8PA3
6 7PA5 31 8PA4
7 7PA6 32 8PA5
8 7PA7 33 8PA6
9 7PB0
34 8PA7
10 7PB1
35 8PB0
11 7PB2
36 8PB1
12 7PB3
37 8PB2
13 7PB4
38 8PB3
14 7PB5
39 8PB4
15 7PB6
40 8PB5
16 7PB7
41 8PB6
17 7PC0 42 8PB7
18 7PC1 43 8PC0
19 7PC2 44 8PC1
20 7PC3 45 8PC2
21 7PC4 46 8PB3
22 7PC5 47 8PB4
23 7PC6 48 8PC5
24 7PC7 49 8PC6
25 GND 50 8PC7

CONNECTOR CN5: 8253 (U5) and 8253 (U10)

PIN 1 1PA0
PIN 26
+5V
2 1ACK 27 GND
3 1AGAT 28 -5V
4 1AOUT 29 GND
5 GND 30 +12V
6 1BCK 31 GND

7 1BGAT 32 -12V
8 1BOUT
33 GND

9 GND
34 GND

10 1CCK


11 1CGAT


12 1COUT


13 GND


14 2ACK


15 2AGAT


16 2AOUT


17 GND

18 2BCK

19 1BGAT


20 2BOUT

21 GND

22 2CCK

23 2CGAT

24 2COUT

25 GND