Measurement Computing PC104-CTR10HD - Manual (Page 11)

To write to or read from a register in decimal or HEX, the weights in Table 3-1 apply:
Table 3-1. Bit Weights
80 128 7
40 64 6
20 32 5
10 16 4
8 8 3
4 4 2
2 2 1
1 1 0
HEX VALUE DECIMAL VALUE BIT POSITION
To write control or data to a register, the individual bits must be set to 0 or 1 then
combined to form a byte. Data read from registers must be analyzed to determine
which bits are on or off.
The method of programming required to set/read bits from bytes is beyond the scope
of this manual. It will be covered in most Introduction To Programming books,
available from a bookstore.
In summary form, the registers and their function are listed on the following table.
Each register has eight bits which may constitute a byte of data or eight individual bit
functions.
Table 2-2. Register Functions
Interrupt & CTR source None BASE + 400h
Commands to 9513 #2 Status of 9513 #2 BASE + 3h
Data for 9513 #2 Data from 9513 #2 BASE + 2h
Commands to 9513 #1 Status of 9513 #1 BASE + 1h
Data for 9513 #1 Data from 9513 #1 BASE + 0h
WRITE FUNCTION READ FUNCTION ADDRESS
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