74LS90 Information is available here.
Part Number : 74LS90, DM74LS90M, DM74LS90N
Function : Decade and Binary Counters.
Package : DIP, SOIC 14 Pin Type
Manufacturer : Fairchild Semiconductor
Some text files in PDF file :
DM74LS90 Decade and Binary Counters
Each of these monolithic counters contains four masterslave flip-flops and additional gating to provide a divide-bytwo counter and a three-stage binary counter for which the count cycle length is divide-by-five for the DM74LS90. All of these counters have a gated zero reset and the DM74LS90 also has gated set-to-nine inputs for use in BCD nine’s complement applications.
To use their maximum count length (decade or four bit binary), the B input is connected to the QA output. The input count pulses are applied to input A and the outputs are as described in the appropriate truth table. A symmetrical divide-by-ten count can be obtained from the DM74LS90 counters by connecting the QD output to the A input and applying the input count to the B input which gives a divide-by-ten square wave at output QA.
1. Typical power dissipation 45 mW
2. Count frequency 42 MHz
[ … ]