Register Architecture - Measurement Computing CIO-DAC08-I User Manual

The CIO-DAC##-I is a simple board to understand. All control and data is
read/written with simple I/O read and write commands. No interrupt or DMA
control software is required. Thus, the board's outputs are easy to control directly
from BASIC, C or PASCAL.
The CIO-DAC##-I has two control and analog output registers.
The first address, or BASE ADDRESS, is determined by the setting of a bank of
switches on the board.
The register descriptions all follow the format:
7 6
A7 A6
the numbers along the top row are the bit positions within the 8-bit byte and the
numbers and symbols in the bottom row are the functions associated with each bit.
To write to or read from a register in decimal or HEX, the following weights apply:
BIT POSITION
0
1
2
3
4
5
6
7

4 REGISTER ARCHITECTURE

5 4
A5 A4
Table 4-1. Register Bit Weights
DECIMAL VALUE
1
2
4
8
16
32
64
128
7
3 2
A3 A2
HEX VALUE
1 0
A1 A0
1
2
4
8
10
20
40
80