National Instruments Low-Cost Multifunction I/O Board for ISA Lab-PC+ - Manual (Page 143)

Appendix D Register Map and Descriptions
© National Instruments Corporation D-27 Lab-PC+ User Manual
Counter A Mode Register
The Counter A Mode Register determines the operation mode for each of the three counters on
the 8253(A) chip. The Counter A Mode Register selects the counter involved, its read/load
mode, its operation mode (that is, any of the 8253's six operation modes), and the counting mode
(binary or BCD counting).
The Counter A Mode Register is an 8-bit register. Bit descriptions for each of these bits are
given in Appendix B, OKI 82C53 Data Sheet.
Address: Base address + 17 (hex)
Type: Write-only
Word Size: 8-bit
Bit Map:
7 6 5 4 3 2 1 0
SC1 SC0 RL1 RL0 M2 M1 M0 BCD