rick@hpdmd48.boi.hp.com (Rick Hoover) (10/01/90)
Hi notes users, I've got an older AT clone (1987) with AMI BIOS and keyboard controller on an Everex motherboard labeled as a Joy Systems computer. However, it appears to not be 100% compatible with software that switches in and out of protected mode. This incompatibility causes my system to loose characters typed at the keyboard when my system switches out of protected mode. I have seen this behavior with OS/2, Windows 3.0 running in standard mode, and disk caching software which uses extended memory in the AT. If I carefully set up my system so it doesn't switch in and out of protected mode, I have no problems with the keyboard. One thing I am fairly certain of, it is not the system BIOS since I have tried using Phoenix BIOS in place of the AMI BIOS without resolving the problem. Therefore, I suspect it is the AMI keyboard controller (an 8042?) which is introducing the imcompatibility. Is it possible that the keyboard controller has a firmware bug in it which causes the system to not see the scan codes coming from the keyboard while the system is resetting when returning to real mode from protected mode? If any one has seen this problem or knows of a solution to it, please drop me an E-Mail message. I will post any working solution on notes when I find it. Thanks, Rick Hoover | ######## / ######## Development Engineer | ####### / ####### Boise Division | ###### /_ __ ###### H E W L E T T Boise, ID | ##### / / / / ##### | ##### / / /__/ ##### Email:rick@hpbsla.hp.com | ###### / ###### P A C K A R D | ####### / ####### | ########/ ########
kdq@demott.COM (Kevin D. Quitt) (10/02/90)
The problem with switching in and out of protected mode on a 286, is
that it can't switch out of protected mode. Intel cleverly left off any
reasonable way to do that. So most people who play the switching game
have to get something to reset the processor (after cleverly saving all
the pertinent info needed for a hot boot - and most of these schemes use
the keyboard to reset the processor.
Since the reset process also takes at least 2 milliseconds, high-
speed serial communications will also be lost.
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Kevin D. Quitt demott!kdq kdq@demott.com
DeMott Electronics Co. 14707 Keswick St. Van Nuys, CA 91405-1266
VOICE (818) 988-4975 FAX (818) 997-1190 MODEM (818) 997-4496 PEP last
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