wluo@brahms.amd.com (Wilbur Luo) (12/04/90)
After some testing, apparently there is a bug with screenpeace. If you were to leave your computer on over the weekend without touching it until monday (i.e., leave it friday afternoon, and come in monday) , the date would be wrong. It would say Saturday. In other words, the date changes correctly Friday night, but it seems that Screenpeace disconnects the 'hooks' that control the date until you touch the computer again. Since you need that 36 hours of not touching the computer, you can see this happen on weekends. (Note, the time is correct). This has happened (consistently) to some 386 machines. We haven't tried it on 286's. We ran 3 machines with Win and Screenpeace, 4 with Windows only, and 3 with Dos only. All 3 running Screenpeace came back messed up. Are there any patches for this? -W
spolsky-joel@cs.yale.edu (Joel Spolsky) (12/04/90)
In article <1990Dec3.162131.27441@amd.com> wluo@brahms.amd.com (Wilbur Luo) writes: >After some testing, apparently there is a bug with screenpeace. >If you were to leave your computer on over the weekend without touching >it until monday (i.e., leave it friday afternoon, and come in monday) >, the date would be wrong. It would say Saturday. This is not a bug with ScreenPeace. It is a bug with MS-DOS. It has been a known bug with MS-DOS since about 1981... The bug is that if you do not query the time for two date changes, only one date change will occur. The problem results because when the timer interrupt, keeping track of seconds passing, wraps around from 2359 to 0000, a flag is set to indicate that the date should be incremented. The date is not actually incremented until you actually check the time, presumably so that timer interrupts take a fixed amount of time, even at midnight, to complete. I guess somebody thought that this would be important for real-time systems. The problem is that as there is only one bit reserved to indicate a date change, _two_ date changes are not treated correctly unless there is at least one clock read between them. One fix would be to leave the windows Clock running which should query the time occasionally and prevent this problem. Joel Spolsky spolsky@cs.yale.edu
wluo@brahms.amd.com (Wilbur Luo) (12/05/90)
I've heard about this bug with the incorrect date in DOS, but I couldn't get it to repeat over the weekend, whereas machines that ran Screenpeace DID show the incorrect date. Are you sure it's not Screenpeace? -W