This part is a kind of semiconductor called 74HC191.
Function of this product has 4 BIT SYNCHRONOUS UP/DOWN COUNTERS.
Manufacturers : SGS-THOMSON
Image and pinout :
Some of the text within the PDF file :
M54/M74HC190 M54/M74HC191 4 BIT SYNCHRONOUS UP/DOWN COUNTERS . HIGH SPEED fMAX = 48 MHz (TYP.) AT VCC = 5 V . LOW POWER DISSIPATION ICC = 4 µA (MAX.) AT TA = 25 °C . HIGH NOISE IMMUNITY VNIH = VNIL = 28 % VCC (MIN.) . OUTPUT DRIVE CAPABILITY 10 LSTTL LOADS . SYMMETRICAL OUTPUT IMPEDANCE IOH = IOL = 4 mA (MIN.) . BALANCED PROPAGATION DELAYS tPLH = tPHL . WIDE OPERATING VOLTAGE RANGE VCC (OPR) = 2 V TO 6 V . PIN AND FUNCTION COMPATIBLE WITH 54/74LS190/191 B1R (Plastic Package) F1R (Ceramic Package) M 1R (Micro Package) C1R (Chip Carrier) ORDER CODES : M54HCXXXF1R M74HCXXXM1R M74HCXXXB1R M74HCXXXC1R PIN CONNECTIONS (top view) DESCRIPTION The M54/74HC190/191 are high speed CMOS 4-BIT SYNCHRONOUS UP/DOWN COUNTERS fabricated in silicon gate C2MOS technology. They have the same h [ ... ]