WOW! That would be a lot of hard work wouldn't it?

Not sure. I already did the hard work patching DOS 7. I mainly would have to port the existing patches over.

I also would have to combine my drive splitter DDO with my BOOTMAN2 DDO.

Of course without FAT-32 it will never support PetaByte Drives as DOS 7 can.

I found that MS-DOS 6.22 has a lot of bugs when it comes to recognising hard drives with partitions beyond the 2 GB barrier, wouldn't it?

The only bug in IO.SYS 6.22, other than the design limitations, is in it's bootstrap code. I have designed a replacement Boot Loader for DOS 7 that could probably be adapted.

The bugs are in COMMAND.COM and elsewhere.

Would the IO.SYS found in DOS 6.22 be hex-edit in order for it to work? If so, can you find the code inside IO.SYS to determine how Type 0x0F partitions would be recongised?

For this purpose DOS 6.22 only needs to accept Type 0xF Partitions as if they were Type 5. This is needed for DOS 7 compatability.

DOS 6.22 only supports CHS so it cannot treat the two Partition types differently.

I have already done this with a small snippet of code.

Thank you for telling me. I have a feeling that the bootstrap code inside IO.SYS in MS-DOS 6.22 is something that can't overcome. So, I have a feeling that I would have to use an appropriate drive overlay to work with hard disks larger than 8,025 MB under DOS 6.22.

The Bootstrap Code is a separate issue. It only limits the C: Partition to 2GB in the first 8GB. Other Partitions are not affected.

I have written a Bootstrap for DOS 7 that has no limits on C:. It should be adaptable to DOS 6.22.

A DDO is required for more than 8GB total on a single Hard Drive as DOS 6.22 uses CHS which can only address 8GB with standard Sector sizes.

The DDO I wrote is small enough that I embedded it within IO.SYS 6.22.

The Bootstrap Code is a separate issue. It only limits the C: Partition to 2GB in the first 8GB. Other Partitions are not affected.

I have written a Bootstrap for DOS 7 that has no limits on C:. It should be adaptable to DOS 6.22.

A DDO is required for more than 8GB total on a single Hard Drive as DOS 6.22 uses CHS which can only address 8GB with standard Sector sizes.

The DDO I wrote is small enough that I embedded it within IO.SYS 6.22.

Thanks again for telling me. It's clear to know that DOS 5 through 6.22 has no support for Logical Block Addressing which indeed limits the size of the hard disk (and other media) to 8,025 MB.

Edited January 3, 201313 yr by ppgrainbow

The Bootstrap Code is a separate issue. It only limits the C: Partition to 2GB in the first 8GB. Other Partitions are not affected.

I have written a Bootstrap for DOS 7 that has no limits on C:. It should be adaptable to DOS 6.22.

A DDO is required for more than 8GB total on a single Hard Drive as DOS 6.22 uses CHS which can only address 8GB with standard Sector sizes.

The DDO I wrote is small enough that I embedded it within IO.SYS 6.22.

Thanks again for telling me. It's clear to know that DOS 5 through 6.22 has no support for Logical Block Addressing which indeed limits the size of the hard disk (and other media) to 8,025 MB.

The limit for normal Logical Hard Drives is 8GB but the limit of other media can be higher. CD/DVD/BD Media use 2KB Sectors so 32GB can be accessed via CHS.

The Bootstrap Code is a separate issue. It only limits the C: Partition to 2GB in the first 8GB. Other Partitions are not affected.

I have written a Bootstrap for DOS 7 that has no limits on C:. It should be adaptable to DOS 6.22.

A DDO is required for more than 8GB total on a single Hard Drive as DOS 6.22 uses CHS which can only address 8GB with standard Sector sizes.

The DDO I wrote is small enough that I embedded it within IO.SYS 6.22.

Thanks again for telling me. It's clear to know that DOS 5 through 6.22 has no support for Logical Block Addressing which indeed limits the size of the hard disk (and other media) to 8,025 MB.

The limit for normal Logical Hard Drives is 8GB but the limit of other media can be higher. CD/DVD/BD Media use 2KB Sectors so 32GB can be accessed via CHS.

Thanks again! I bet that MS-DOS might be capable of accessing DVD-ROM drives, but I don't know they'll be able to recongise DVDs above 2 GB due to MS-DOS using signed 32-bit values to calculate total disk space in bytes. Probably not.

I never said everything would work perfectly or not require Patching, but it is doable.

I never said everything would work perfectly or not require Patching, but it is doable.

Indeed, it is.