wtm@uhura.neoucom.EDU (Bill Mayhew) (05/28/90)
The PC6300 clock is odd. The design predates the IBM AT computer, and thus is not wired in a fashion that is compatible with the AT. In order for the clock to work correctly, it is advisable to run the machine with AT&T-branded msdos release. There are some bugs in the AT&T dos. Early releases of 3.2 reset the RTC seconds register to 00 every time the machine was rebooted. I believe 3.2 relase 1.02 or higher did not have the flaw. A patch was circulated on the net to fix early releases of 3.2. DOS 3.3 does not have the RTC set bug. 3.3 also knows about the newer AT&T machines that do have AT-compatible clocks. IBM DOS on the 6300 goofs up the time of day while DOS is running. The 8253 timer is programmed by the BIOS to tick at a different rate on the 6300, which makes the clock run about 10% fast when the machine is booted from IBM-branded DOS. It is possible to reset the 8253 timer on the fly with a couple of outputs to the control port. I recall a long time ago, I used DEBUG < TFIX in my AUTOEXEC.BAT file to affect the fix when I ran IBM DOS on my 6300. I don't recall the numbers any more. TFIX just contains the commands as you would have typed them manually into DEBUG. Another thing about the 6300. The RTC clock battery is a nickel-cadmium battery. The machine needs to be run for a few hours every couple of days or so to prevent the battery from going dead. ==Bill== -- Bill Mayhew Northeastern Ohio Universities College of Medicine Rootstown, OH 44272-9995 USA 216-325-2511 wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm