Win95 disk can format 4gb fat16 partition why can't run 95

[mkbea1985]

After I had installed nt 4.0 on some computer of mine I was able to use a Windows 95 boot disk and format the 4gb fat16 partition made by NT. So if a windows 95 dos format utility can recognize a 4 gb fat16 partition why can't you at least run Windows 95 osr2 or higher on it?

[Overdoze]

DOS (and possibly its Windows 9X descendants as well) only supports 32KB clustered FAT16, which results in a 2GB max partition size limit. Anything beyond that can cause compatibility issues. Windows NT increased this limit by using 64KB clusters, which pushes the upper limit to 4GB. I tried this myself and voila, CHKDSK hangs/crashes while checking such a partition.

It's interesting that FORMAT will still format a 4GB FAT16 partition with FAT16, despite the fact that blank 4GB partitions are by default formatted with FAT32.

[JustZisGuy]

The use of FAT16 or FAT32 is determined by the partition type. You will have to use FDISK to remove the FAT16 partition and create a new FAT32 partition. DOS/Windows 9x does not support the NT 4GB FAT16 partitions. It is surprising that the formatter doesn't reject it.

[rloew]

DOS and Windows 9x support 64KB Clusters. Only some of the utilities do not.
With some Patches and large sector emulation I have been able to increase the limit to 8MB per Cluster for DOS and 1MB per Cluster for Windows.
This allows 512GB and 64GB FAT16 Partitions respectively.

[RentedMule]

DOS and Windows 9x support 64KB Clusters. Only some of the utilities do not.
With some Patches and large sector emulation I have been able to increase the limit to 8MB per Cluster for DOS and 1MB per Cluster for Windows.
This allows 512GB and 64GB FAT16 Partitions respectively.

I'm not sure why anything would support past 64k clusters. Referencing https://staff.washington.edu/dittrich/m ... gen103.pdf

If you look at the definition of BPB_SecPerClus, you will read:

Note however, that a value should never be used that
results in a “bytes per cluster” value (BPB_BytsPerSec *
BPB_SecPerClus) greater than 32K (32 * 1024). There is a
misconception that values greater than this are OK. Values that
cause a cluster size greater than 32K bytes do not work properly; do
not try to define one. Some versions of some systems allow 64K
bytes per cluster value.

So at the very most, as per spec, you shouldn't even consider BPB_BytsPerSec *
BPB_SecPerClus > 64k to be valid. Not even linux does.

[rloew]

I never said I followed the standard specification.
I was able to support 256 Sector Clusters by using 00 as the BPB_SecPerClus Byte and converting it to 0x100 when copied to wider arguments.
I also emulated Sector Sizes up to 32768 Bytes per Sector, which is supported by BPB_BytesPerSec.
I did have to replace the entire Loader in IO.SYS to make it Bootable.

[os2fan2]

I have been running Windows 95 OSR1, on top of msdos 7.10.2400 (a patched version of the dos in 2222).

Even though you can access fat32 partitions in plain DOS, on this rig, you can't access the same fat32 partitions under Windows. You can see them in Windows 3.10 though!.

Denesco wrote a dos71.sys file that makes DosME think it's 7.1 for the sake of SYS. It converts '8.0' to '7.1'. I made a few versions so that it would convert 7.1 from IO.SYS into 6.30, 7.00 and 8.00. You basically load it in the appropriate section of a config.sys, and you can some weird tests with it. In essence, the 'upgrade' test depends on the DOS version the dos reports. Likewise you can't run DOS sessions from anything other than 7.00 (ie winoldap checks for dosver = 7.00 here). So if you want DOS apps from Windows, you have to load dos70.sys.

You can restart the logo after the boot with a "logo" command in config.sys. However we use a different system where you can load a varying logo as the startup runs, viz a dos logo for dos sessions, and a win95 for 95 logos, and a 98se for 98se logos. This is part of making the multi-os windows look authentic.

[redspl]

I had very similiar problems with win98se last time I've tried to install it - fixed by making a new partition table in gparted(through pata/sata->usb2.0 converter) and then making some DOS partitions in MS DOS fdisk.

[rloew]

I have found a problem with GParted. If you create Primary FAT16 or FAT32 Partitions on a large (>8GB) Hard Drive it will use the CHS (6 or 0xB respectively) not the LBA (0xE or 0xC respectively) Partition Types. This makes the Partitions unuseable in 9x and may lead to corruption of other Partitions.

[redspl]

rloew, that's why I don't use gparted to create partitions Normally, I'd use Windows XP+(or is that 2k+?) built-in partitioning utility, or fdisk and as formatting tool, I'd use HP Disk Format Utility or format.com.

[rloew]

redspl. You mentioned using it in your previous post, so I posted the warning.