Hi all guy´s. I´ve been using MS DOS 7.10 for several time, about 3 or 4 years in all desktop machines without mayor problems. Two mounth ago, I buyed a Texas Instruments Travelmate 4000 (lap top 486 dx2 8Mb RAM, 209 Mb hd, the hd has faulty sectors, so I replace it with a 1Gb). I also installed MS DOS 7.10 in that machine. The old HD went to an older Compaq Aero 4/25 Dx 25 MHz, 8 MB Ram) also with 7.10. A friend gives me an more older Carry I machine (386, no copro, 16 MHz, 2 Mb Ram, a 15 GB disk with Ontack Disk manager installed in it) an the same 7.10. The 386 had the DS1287´s battery exausted, so I replace the lithium battery inside it, and start as new. All the 3 computers above mentioned are made from different manufacturers, different config.sys and autoexec.bat, but the same version of DOS. The 3 smaller pc´s has the same trouble: after 3 to 6 times booting, the bootup process crashed while executing autoexec.bat, particularily when loading lh killer.exe Starting with the F8 key, and executing 1 line at a time, the system hangs on differnt lines in a same machine (the Texas one). I triyed to "rem" some lines, in the autoexec.bat, but the OS was unstable, although when recently installed, worked properly. So, I decided to start with F8 key, and try to not load some lines in the config.sys to see if the trouble appears during loading autoexec, but the system hangs because of a bad line in the config.sys. When I by pass the 3 firsts lines in config.sys, the system looks stable. So, I retryed bypassing one of these 3 lines, one at time, and I found that when I bypass a line like this: dos=high,umb,auto the machine also looks stable. At this point, I searched in help.com what does this command do. It appears to manage where the DOS is loaded. Then I try the suggestions in that help, and try this: dos=high,noumb,auto dos=high,umb,noauto and in this way, the machine appears to work properly. May be a conflict with lower clock/lower memory machines? Any suggestions are welcomed !!! Very Thanks. Osvaldo. Barrio Garay. Buenos Aires, Argentina If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.

Try it with just: DOS=HIGH,UMB Here's some info on that command: http://www.nukesoft.co.uk/msdos/com... It loads drivers and dos system files (as much as is possible) in the memory area between 640K and 1 gig leaving the lower 640K available to run software. You may want to post back the contents of your config.sys and autoexec.bat. What is KILLER.EXE? That's the name of a file created by malware but I assume your's has a different function.

Hi Dave. Ok, I´ll try this sugestions. Mmmm, I don´t know what exacly killer.exe does. It is loaded during autoexec.bat, and apparently detects and prevents bad opcodes to the µPC, but my experience tell that this program causes more problems that those that are solved by it. I had a game that was corrupted, and when exiting from i, the killer appears and halt the system. When I removed it from autoexec, the cpu simply hangs up. It´s very rare program. Very Thanks. If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.

I've tried to find out more about this Killer.exe. Best I can determine, it is a DOS TSR that is supposed to detect invalid opcodes and "abort to DOS" to keep the CPU from freezing or getting hung on the bad opcode. In other words, it "kills" the process which issued the invalid opcode. But, how does this TSR "know" what is an invalid opcode? Opcodes are specific to a particular CPU. What model/type CPU is this Killer.exe written for? For example, if it is based on the 8086 instruction set, then it will "kill" a program which tried to run one of the extended opcodes for the 80386 CPU, EVEN IF THE PROGRAM WAS RUNNING ON A 80386 CPU. If it is based on the 80386 instruction set, then it will reject any 80486 specific opcodes. While the 80386 instruction set is backward compatible with the 80286 and 8086 instruction sets, the same is not true going forward. I don't think I'd load this killer.exe unless I knew exactly what it was doing. I'm sure there are special applications where this program could be very useful, but I don't think it should be loaded into a routine working DOS environment.

Pyrolitic: I also don´t know what that program does. It is installed with the dos 7.10 diskettes that I´ve downloaded from Internet. But my experience is that it causes several problems that those supossed to avoid. So, in almost all my autexec.bat the line where it is called, I´d removed it or "rem"ed so it don´t work. Some time ago, I´d downloaded a tetris game that when exiting, the killer.exe worked stopping the cpu. When I removed it, the 486 simply hangs up. Curiously, in both cases, the end of the story is the same: reset the CPU. So it program, is very stupid. If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.

perhaps it is the UMBs in your computers that are being misdetected. Try removin the UMB option and see if your problems go away.