Register-Level Programming Chapter 4
Lab-NB User Manual 4-24 © National Instruments Corporation
Counter B Mode Register
The Counter B Mode Register determines the operation mode for each of the three counters on
the 8253(B) chip. The Counter B 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 Mode Register is an 8-bit register. Bit descriptions for each of these bits are given
in Appendix C, AMD 8253 Data Sheet.
Address: Base address + 4 8030 (hex)
Type: Write-only
Word Size: 8-bit
Bit Map:
76543210
SC1 SC0 RL1 RL0 M2 M1 M0 BCD