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504 MB though BIOS recognizes 2 GB

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    504 MB though BIOS recognizes 2 GB

    Hello,

    I've bought another 486 computer. FDISK does only recognize 504 MB of hard drive space which an error I am normally aware of but this computer seems to have an interesting problem. Normally, 504 MB would be 1,024 cylinders if I am not wrong and the BIOS should only see 1,024 cylinders when doing an HDD scan. But this BIOS (Award Modular BIOS 2.50g) recognizes all 16,384 cylinders the HDD has (40 GB; the amount of cylinders is written on the HDD). That means, DOS should normally be able to use as much space as it supports (I think 8 GB).
    Would you try to boot a small Linux distribution like Tomsrtbt and try to format it with Linux or try to make a BIOS update? Maybe that is normal and it is just me thinking wrong, I am thankful for any information you have for me

    Best regards,
    lxndio

    #2
    Yes, you can try partitioning and formatting the drive on another system / OS. Another option is using Dynamic Drive Overlay, a nifty software solution. EZ-Drive or Ontrack. But try the first version first. What make is your HDD?

    Comment


      #3
      I'd recommend finding a dynamic disk overlay program such as EZ Drive or Ontrack to override the motherboard's BIOS and allow the drive to be used at full capacity. What brand/ model drive is it?

      Comment


        #4
        The BIOS does not recognize 2 GB. The drive reports itself as a 2 GB drive and that's what you're seeing. 504 MB is that actual BIOS limit.

        Either a BIOS update or using a DDO as Moondog suggested are the two main options. Alternatively you could install an IDE interface with a BIOS on it.
        PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

        Comment


          #5
          Originally posted by lxndio View Post
          That means, DOS should normally be able to use as much space as it supports (I think 8 GB).
          Unless you have a version of DOS that can work with FAT32 partitions then the maximum partition size is 2 GB, which is the limit of FAT16. You could create 24 partitions (drive letters C-Z) to get a total of 48 GB of drive space if you had drive overlay software on FAT16.

          The only DOS distributions I know of that support FAT32 partitions are:

          MS-DOS 7.10 (included with Win9x)
          DR-DOS 7.x
          FreeDOS

          DR-DOS and FreeDOS have some known compatibility issues with some programs, TSRs and drivers written for MS-DOS. FreeDOS is one of the only DOS distributions left though that's still in development and open sourced.

          Comment


            #6
            Originally posted by GiGaBiTe View Post
            Unless you have a version of DOS that can work with FAT32 partitions then the maximum partition size is 2 GB, which is the limit of FAT16. You could create 24 partitions (drive letters C-Z) to get a total of 48 GB of drive space if you had drive overlay software on FAT16.
            Another dodge was to use a driver to map larger drives as network shares.

            Interestingly, I have an older digicam that uses CF for storage, but it only understands FAT16 filesystems. You'd think that this would limit me to 2GB volumes, but, using Windows XP, it's possible to format a CF to 4GB using FAT16. I've never tried to use pre Win95C DOS to play with those volumes, however.

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              #7
              In your BIOS setup look for a translation setting - some offered Normal / Large - Normal gives you a 504MB limit, Large I think is 2GB.
              Not all 486's have this, but some do, so it's worth checking. If you switch from Normal/CHS to Large you'll likely need to partition and format it again.
              Twitter / YouTube

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                #8
                Originally posted by SpidersWeb View Post
                In your BIOS setup look for a translation setting - some offered Normal / Large - Normal gives you a 504MB limit, Large I think is 2GB.
                Not all 486's have this, but some do, so it's worth checking. If you switch from Normal/CHS to Large you'll likely need to partition and format it again.
                I already looked for such a setting but the BIOS does not have it.

                I think I will try EZ-Disk tomorrow. That may be a good solution.

                Comment


                  #9
                  Originally posted by Chuck(G) View Post
                  Another dodge was to use a driver to map larger drives as network shares.

                  Interestingly, I have an older digicam that uses CF for storage, but it only understands FAT16 filesystems. You'd think that this would limit me to 2GB volumes, but, using Windows XP, it's possible to format a CF to 4GB using FAT16. I've never tried to use pre Win95C DOS to play with those volumes, however.
                  According to this:

                  https://support.microsoft.com/en-us/kb/310561

                  It looks like only Windows XP, 2000 and NT4 supports the necessary 64k cluster size for a 4 GB FAT16 partition.

                  Comment


                    #10
                    Originally posted by GiGaBiTe View Post
                    According to this:

                    https://support.microsoft.com/en-us/kb/310561

                    It looks like only Windows XP, 2000 and NT4 supports the necessary 64k cluster size for a 4 GB FAT16 partition.
                    That's probably true--some arithmetic limitation--signed vs. unsigned numbers? Interesting that my lowly digicam had no problem with it. I've never tried it on DOS; 64K for a cluster is just too wasteful for small files. Better to go with FAT32 if you can.

                    Comment


                      #11
                      It's a limitation on the number of clusters and the cluster size.

                      FAT16 has a maximum number of 65524 clusters and a 32k cluster size, so the max you can address is 2096768 kilobytes (2047.625 MB)

                      Windows NT/2000/XP just up the maximum cluster size to 64k without changing the maximum number of clusters, so you can address is 4193536 kilobytes (4095.25 MB)

                      The risk of data loss from corruption is rather high from the non-standard implementation that Windows NT uses, so it's probably best not to use it.

                      Comment


                        #12
                        On my digicam, it's never failed to work with 4GB CF cards as long as I've owned it--which is several years.

                        On a whim, I just formatted up a 4GB USB card using FAT16 and thought I'd see what Win98SE thought of it. It doesn't seem to barf and I can read files from it, but I wouldn't trust the reliability of it. It even passes CHKDSK without a problem.

                        FWIW, I do this because the digicam doesn't understand FAT32.
                        Last edited by Chuck(G); July 10, 2015, 07:16 PM.

                        Comment


                          #13
                          As a side note, Wikipedia once mentioned that FCBs in MS-DOS don't work properly with >2GB FAT16 partitions, but don't mention why. It is because when the FCB "reserved" fields was changed for DOS 5.0, they decided to steal the high two bits for attributes in one of them, so the directory sector field was expanded to only 22-bit compared to 16-bit previously (loading SHARE worked as a workaround because they used a different structure in this case).

                          Comment


                            #14
                            Didn't Microsoft make noises that FCB support was deprecated around 5.0? After all, they were just a structure inherited from CP/M (FCBs, not Microsoft), like the jump to PSP+5 to issue DOS requests (or the jump to PSP+0 to end a program). It's worthwhile noting that these were copied from 8-bit CP/M 2.2.

                            Comment


                              #15
                              Yea, similar reasons was why FCBs was mostly disabled for FAT32 volumes in MS-DOS 7.1 too. IMS REAL/32 still had to support FCBs on FAT32 for CP/M-86 programs so DOS programs got it for almost free.
                              Last edited by yuhong; July 13, 2015, 12:33 AM.

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