Model D/A-06A can be installed in I/O slots of PC/ XT/AT class computers. It economically provides six independent 12-bit Digital-to-Analog Converters (DAC) and 24 digital input/output channels. Each DAC has double-buffered input for single step update and occupies a unique address location. Analog Output Update Mode is selected by a selector switch on this card. Three update modes are available:
- Individual update of each channel.
- Simultaneous update of all selected channels.
- Simultaneous update of all selected channels upon receipt of an external signal.
(
Note: This mode requires use of six digital I/O lines on Port C.)
Digital I/O channels are provided from a type 8255 Programmable Peripheral Interface (PPI). The PPI has 24 I/O bits which may be programmed in three modes of operation:
- Mode 0: Each group of 8 I/O bits may be setup to be input or output.
- Mode 1: Each group may be setup to have eight lines of input or output. (Note: in this mode, three lines are used for handshaking and interrupt-control signals.)
- Mode 2: Eight lines are used for bidirectional bus and five lines are used for handshaking.
Base address selection is via on-card DIP switches and the D/A-06A requires 16 consecutive I/O address locations. The base address can be selected anywhere within the I/O address range of 000-3FF (hex) providing that the address locations do not overlap other functions. Data are written to the DAC's in right-justified 2-byte binary format (8 LSB's and 4 MSB's). For example:
Unipolar Ranges:
0000 0000 0000 = Zero
1000 0000 0000 = ½ Scale
1111 1111 1111 = Full Scale
Bipolar Ranges:
0000 0000 0000 = Neg. Full Scale
1000 0000 0000 = Zero
1111 1111 1111 = Pos.FullScale
