User's Manual

Lab-NB User Manual 4-20 © National Instruments Corporation

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 C, AMD 8253 Data Sheet.

Address: Base address + 4 0030 (hex)

Type: Write-only

Word Size: 8-bit

Bit Map:

76543210

SC1 SC0 RL1 RL0 M2 M1 M0 BCD