Any old coots here that know/remember DR DOS? (sorta like MS DOS)
 

Hi

I have a CNC machine tool that is controlled by a piece of software running on a dedicated PC (mounted to the machine) that uses DR DOS as the OS. The PC's only function is to run the basic NC software that controls the machine. The PC is an old Pentium board, hard disk, 1.44 MB floppy, not much else. The machine is about 13 years old, mint condition everything.

Normally, when the machine is turned on the PC boots up and the autoexec.bat file changes directories and starts the control software. Never had a problem until a couple days ago.

The PC seems to boot normally, starts the control software, BUT the main menu of my control software no longer appears and I get a message generated by the software itself saying: "Not enough virtual memory, press any key to continue". Hit any key, get kicked back out to c: prompt.

The machine manufacturer is not super helpful, they said to look for a file called VMEM and delete it, (some sort of virtual memory error file) and then reboot. Deleting it and restarting my control software worked for me once, but no longer does. Tried adding del VMEM.* to the autoexec.bat file and still no worky. I can delete the VMEM file, start the software from the c: prompt, and it will kick me back to the "Not enough memory" screen immediately and generate a new VMEM file...I'm stuck in a loop.

Finally the question: in DR DOS is there a setting to allocate Virtual memory that possibly got corrupted, or is there a BIOS setting that corrupted, or what should I look for? Sure seems like the control software is telling it can't even start because it has no virtual memory available. I'm not sure if I have a software issue or a hardware issue, but the hardware seems to work fine- it finds the hard disk, monitor, chipset, etc.

??

Thanks.

Try the memory test on the ultimate boot CD and see if some RAM went bad, assuming no one changed any of the memory parameters in the config.sys file.

lol DR DOS. i don't think i'm THAT old...but i used it.

i'm trying to remember...but i know there was a system filed named EMM386.EXE(? or was it SYS?) that handled virtual memory.

it had to be loaded via config.sys i think.

also could be your hard drive is filled up that the system does't have enough space to create a swap file.

My vote as well. Clear out some of the old crap!

Yea, I bet it is a problem with the hard drive. You need to clone that drive and replace it just because it is so old.

I used DR Dos for a while. I don't remember why I went back to MS DOS. I still have a factory box and disks with Dos 6.1

I'm assuming you have powered down the hardware, left it off for 30 seconds etc. I wouldn't mess with the config.sys and autoexec.bat as they haven't been altered. Another idea is to (very) carefully reseat the cards in the machine.

13 y/o hardware.... pentium II or III ?

either way I'd not go too crazy wtihout ruling out some sort of hardware failure or weirdness like heat creep.

I'd also put the drive in another machine and make a good backup, or boot with a livecd and do it. Most linux live disks have memtest on 'em as well.

After you have a good backup, test it by putting it on a new drive and booting it.

your hard drive is probably full. you may need to offload large CNC files? what's the output of the c:\dir command? It should give a summary....

I think its the floppy disk. If its complaining about virtual memory, that indicates that its trying to create a swap file on the floppy disk, and it doesn't have space. Often this was done to decompress drivers need to access the hardware. If only a few sectors of the floppy are bad, it may be unable to create the swap file.


If you happen to have a computer with a floppy disk drive, you might try making a copy of the original disk, and try it. Its possible that there are error (dump) files on the disk taking up space. But given the the length of time this thing has been in service, I doubt that the case. Bad floppy disk.

BTW, I have to assume that one could transfer the startup file to a CD drive, and remap the startup sequence to hit the CD.

The floppy disk is a MacGuffin. He's booting from the c: drive, which in DOS is the fixed disk (hard drive).

Thanks for the replies. I will check out a few of the things you guys ask about and report back.