5 Mhz is the Maximum clock frequency in 8086.

Because of high stability, large Q (Quality Factor) & the frequency that doesn't drift with aging. Crystal is used as a clock source most of the times.

The standard CMOS Setup screens from various BIOS manufacturers all provide the same basic information. For example, they can be used to set the date and time via the system clock/calendar.COMS, BIOS

If the time is incorrect on a PC system, the easiest way to reset it is through the operating system. However, if the system continually fails to keep good time, you should start by checking that corrosion has not built up on the battery contacts. Clean the contacts with a pencil eraser and retry the battery. If that doesn't work, try replacing the battery. Next you can try replacing the RTC module. If this does not correct the time keeping problem, the electronic circuitry that recharges the battery might be defective, and in this case you will need a new motherboard.

(I had made it through a series of interviews for a position in New York City that paid about $60,000 per year. After interviewing with the manager and owner of the company, I had a gut feeling that they expected employees to work 14-hour days plus weekends. How could I ask a question about work hours without appearing lazy or like a clock-watcher? So at the end of my third interview, I asked the manager that question. Her face turned a bit sullen as she said, "Well, I had fun at the company business party we had on our business trip to Canada." From that one question, I learned that if I accepted the position, I'd be signing my life away to this company.)

clock skew is the time difference between the arrival of active clock edge to different flipflops of the same chip.