The AD12-8G is an eight-channel, 12-bit, analog/digital card for use in IBM Personal Computers. It is a 3/4 length card that can be installed in expansion slots of ISA-bus computers. All connections are made through a standard 37-pin D type connector that projects through the rear of the computer.
ANALOG INPUTS
The input analog channels are individually switch selectable for either differential or single-ended input signals. A choice of nine software-selectable voltage ranges are available and the card can withstand ±30 VDC overload and transients of several hundred volts. The A/D converter is a successive-approximation type with solid-state input analog multiplexer and sample and hold amplifier. A/D conversion time is typically 25 microseconds.
COUNTER/TIMER
This card also contains a type 8254 counter/timer chip which has three 16-bit counters. These counters can be used as an A/D pacer clock and/or can be used to measure pulse width, count events, measure or generate frequencies, etc. An on-board 1 MHz crystal controlled clock is hard-wired to one counter input and the clock inputs to the other two counters are available at the I/O connector. All the gate inputs and counter outputs are accessible at the I/O connector.
DIGITAL I/O
AD12-8G also can accept three bits of digital input and can provide four bits of digital output both in standard TTL/CMOS logic levels. One of these outputs, for example, can be used to initiate an interrupt upon end of A/D conversion. Jumper positions on the card provide means to assert interrupts on your choice of levels 2 through 7.
