I have some DOS computers that lose about 4 minutes per day. Have changed the battery to no avail. Any ideas? Steve

There is no clock to speak of in DOS - any timekeeping is based on the hardware system clock. There is a switch for HIMEM.SYS: /CPUCLOCK:ON|OFF Specifies whether HIMEM is to affect the clock speed of your computer. If your computer's clock speed changes when you install HIMEM, specifying /CPUCLOCK:ON may correct the problem; however, enabling this option slows down HIMEM. The default setting is /CPUCLOCK:OFF. Why don't they make computers that will do what we think we want them to do?

Does the computers have a CMOS clock in them that keeps track of the time and date when the system is powered off? The existence of a CMOS battery indicates that they do. This CMOS clock is usually accurate to within seven seconds per day or better. So when you reboot, it should have the right time (more or less). However, once the system is booted and set with the time from the CMOS clock, the system time (the one you can access) is kept by the system software and is based on a not so accurate crystal on the system board. These are usually only accurate to within four minutes per day (more or less). So losing/gaining up to four minutes per day would be normal for many systems. It is assumed that you would be rebooting the system once per day. And if you need a more accurate time on a system, it is assumed you would have access to some sort of time standard source. Some versions of DOS have an optional device driver that can be loaded which redirect time requests to the software clock to the CMOS clock hardware. This slows things down a little, but is one solution to more accurate time.