On Fri, Jun 17, 2016 at 6:17 PM, Brandon Taylor <donnie126_2...@hotmail.com> wrote: > Well, now, this is very odd indeed. The copy of FreeDOS that I got with > Rufus apparently does not come with a MEM command. Possibly it’s an old > version, or a stripped-down version, or just broken? Anyway, I’ll try > downloading FreeDOS from SourceForge and see what happens next.
See my earlier comments about looking at DOSBox. But the Rufus version may not include MEM. MEM is part of a full DOS distribution, and I suspect what Rufus installed was just enough to boot DOS. PCs running DOS had a 640K limit on conventional memory. This was an architectural limitation originally imposed by IBM. The 8088 CPU early DOS PCs used had a 1MB address space, but IBM chose to reserve memory above 640K for system functions. When you booted a PC, DOS itself got loaded into that 640 K, in the form of two system files, and then COMMAND.COM was loaded, and served as the shell you interacted with. It would relocate itself to the top of available memory, and was in two parts - a resident portion, and a transient portion that contained the interpreter you talked to. Load a program from the command line, and the program was loaded into space occupied by the transient portion. Exit the program, and the resident portion reloaded the transient part from disk. You probably had about 600K free memory after DOS was loaded for use by programs. DOS looked for the files CONFIG.SYS and AUTOEXEC.BAT when it booted. CONFIG.SYS was where you specified drivers you wanted to load on boot. AUTOEXEC.BAT was processed by COMMAND.COM, and where you did things like set your PATH and load any Terminate and Stay Resident programs you used. It was possible to install more than 640K of RAM, and various tricks were used to make use of it. You could configure the additional memory as Expanded (EMS) or Extended (XMS) memory, and programs written to make use of them could get access. The technique involved creating a 64K window in the address space above 640 K, and making EMS or XMS available in 64K chunks in that window. You could also implement a "High" memory area in that address space, and load drivers and TSRs there to get them out of the convention memory your programs wanted to use. The MEM command was designed to let you examine memory and see how you could configure things. To use EMS or XMS memory, or activate the HMA and load things there, you needed drivers loaded in CONFIG.SYS. Look at whether there is a CONFIG.SYS file or AUTOEXEC.BAT file created by the Rufus install, and post what's currently in them. (They are plain text files, view-able and modifiable in an editor.) The first step is to see what environment Rufus creates by default. > Brandon Taylor ______ Dennis ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports. http://sdm.link/zohomanageengine _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
