Keithley / MetraByte DAS-8 Analog-to-Digital Converter

The Keithley/MetraByte DAS-8 is a 12-bit successive approximation analog-to-digital converter for data acquisition on ISA bus PCs. It provides eight configurable analog input channels, fixed ±5V range, and 25 µs typical conversion time, delivering up to 4 kS/s sampling rates. The board integrates an Intel 82C54 programmable counter-timer with three internal 16-bit counters for event counting, pulse generation, and timing measurements. Seven bits of TTL digital I/O—comprising a 4-bit output port and 3-bit input port—enable direct hardware interfacing. A precision +10.00V (±0.1V) reference voltage output is derived from the ADC reference and available on the rear D-type connector. The DAS-8 operates from the ISA bus clock (4.77 to 8 MHz) and supports hardware interrupts on levels 2–7. Base address defaults to 768 decimal (0x300 hex) but is user-reconfigurable via DIP switches.

## Technical Specifications

• **Analog Input Channels:** 8
• **ADC Resolution:** 12-bit
• **Conversion Method:** Successive approximation with sample and hold
• **Input Range:** ±5V (fixed)
• **Conversion Time:** 25 µs typical, 35 µs maximum
• **Maximum Sampling Rate:** 4 kS/s
• **Counter/Timer:** Intel 82C54 with three 16-bit counters
• **Clock Source:** ISA bus clock (4.77 MHz, 6 MHz, or 8 MHz)
• **Digital I/O:** 7-bit TTL (4-bit output, 3-bit input)
• **Reference Voltage Output:** +10.00V (±0.1V)
• **Interrupts:** Hardware interrupts, levels 2–7
• **Base Address:** 768 decimal (0x300 hex), DIP-switch configurable

## Key Features

• Single-ended or differential analog input configuration
• Programmable interval timer supports event counting, frequency measurement, and waveform generation
• TTL digital I/O for direct sensor and control interfacing
• Precision reference voltage available to external circuitry
• ISA bus integration for legacy PC systems

## Typical Applications

Data logging, industrial process monitoring, real-time signal acquisition, event timing and counting, and periodic sampling with software control via DriverLINX or compatible data acquisition packages.

## Compatibility & Integration

The DAS-8 operates under MS-DOS and supports VIEWDAC, EASYEST LX, EASYEST AG, ASYST (version 2.10 or greater), DriverLINX, and Daqarta for DOS software environments.