Introduction
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I n t r o d u c t i o n
The PET-48DIO is a digital input / output add-on card with 48
programmable I/O ports for IBM PC or compatibles. In addition to
programmable I/O ports, an event counting and a timer pacer for
interrupt are also included. The 48 programmable input / output ports
are divided into two 24 programmable input / output ports for each
group. Its pin assignment is fully compatible with opto -22 standard.
The features of the PET-48DIO include an event counter to count
events that come from input port, a timer pacer for interrupt trigger,
and four input ports can be as programmable real time interrupt
source. Thes e functionality make the PET-48DIO are very powerful to
support complex digital I/O control applications.
Only two bytes of I/O address are occupied by PET-48DIO, it lets
more cards can be installed in one system. All digital input / output
ports are TTL compatible and use the 74LS244 as driver and buffer
circuit to provide higher driving capacity for outputs and lower loading
current for inputs than regular TTL circuit.
1.1 Specifications
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General Specification
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48 programmable input / output ports
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High output driving capacity
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Low input loading
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One 16-bit programmable event counter
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One 32-bit programmable timer pacer
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Interrupt IRQ : IRQ3, ..., IRQ15 (9 levels jumper selectable)
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Digital Input
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Logic level 0 : From -0.5 V to 0.8 V