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:

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

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.

&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

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.

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)

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

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

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