[ppgrainbow]

Hello!

I recently scored a used Fujitsu Point 510 tablet PC from eBay for Christmas. The price for the used product was $149.95.

Manufactured in July 1998, it features a AMD 5x86 processor running at 100 MHz with a 2.16 GB hard drive and only 8 MB of EDO RAM, upgradable to 56 MB with 1 MB of VRAM.

The problem with the Fujitsu Point 510 is this ... the unit does NOT have a floppy drive and data can ONLY be transferred via a 2 GB compact flash drive when the PCMCIA drivers are installed. I'm looking to get a Portable Port Expander (model number FMW26CR5) and a external floppy disk drive (FMWFD2).

Furthermore, the Point 510 came with MS-DOS 6.2 and Windows for Workgroups 3.11 pre-installed, before I installed MS-DOS 6.22 and Windows 3.1. The Point 510 is one of the last tablet PC and other portable computers to support MS-DOS and Windows 3.1x before it was dropped due to architectural limitations.

Unfortunately, MS-DOS can't recognise all of the disk space, because the maximum amount of disk space that it can use is 2 GB or 65,510 clusters at 32 kilobytes per cluster. The hard disk that has 4,200 cylinders, 16 heads and 63 sectors per track...that totals 2,167,603,200 bytes or almost 2.02 GB which is pushing over the MS-DOS limitations. When I ran FDISK the other day, when I was considering creating a logical DOS partition, only 16 MB of disk space was usable on what was going to be Drive D.

Since the unit only has 8 MB of memory installed, can you recommend me some utilities that will perform non-destructive hard disk resizing under MS-DOS or FreeDOS? I want to be able to shrink the drive to 1,032 MB for the primary DOS partition and create a 1,031 MB logical partition in the extended DOS partition.

Also, is there anyway to purchase a portable port expander and external floppy disk drive for the Point 510 unit if I can try to find one?

If so, how would it be done?

This post has been edited by ppgrainbow: 29 December 2012 - 03:14 AM

[dencorso]

Hi, ppgrainbow!

With all due respect, I read your post and I understood it almost fully, but the last line in it got me perplex...
I've thought real hard about it, but I remain wondering what did you intend to mean when you wrote this:

ppgrainbow, on 29 December 2012 - 02:53 AM, said:

If so, how would it be done.

My only guess is that you forgot to add a question mark, thus it would instead read:

"If so, how would it be done?"

But, even if I'm right, I still remain struggling with "so" and "it"... I mean, "it" can be the partition resizing, OK, but what does "so" refer to?

[ppgrainbow]

Thank you for the help. I edited this thread before you posted here.

Well...anyways, I am stumped trying to find a good DOS or Win16 utility that will resize the partition without destroying the data on the hard drive. I mean, if there was data corruption on the drive, the tablet PC would be useless unless it is taken in for repairs.

This post has been edited by ppgrainbow: 29 December 2012 - 03:18 AM

[dencorso]

Well, I, for one, would create a full disk image from the HDD as it is, before trying anything on it. So, in case all goes wrong afterwards, it'd be just a matter of redeploying the image, and all would be back to square one. Full disk image backups, no matter how long it takes to create them in a given machine, are the best advice I can give, and one that I follow personally punctiliously, whenever I lay my hands on a machine I intend yo service...
Better safe than sorry, you know.

[jaclaz]

Sure, creating a dd-like image before fiddling with ANY disk tool is ALWAYS a good idea .

First thing I would try would be FIPS .

You can get it from the UBCD (which contains several more possibly useful DOs/FreedDOS utilities) allright:
http://www.ultimatebootcd.com/

Or from here:
http://ftp.dk.freebs...ools/srcs/fips/
Some instructions/info:
http://www.informit....=32084&seqNum=2
http://www-uxsup.csx...lboot-fips.html

jaclaz

[ppgrainbow]

Thanks for the help, jaclaz. I appreciate it.

Gere's what I did. For testing purposes, I created a hard disk image of 2,070 MB in capacity and here's what the partition table currently looks like:

Partition table:

     |        |     Start      |      |      End       | Start  |Number of|    
Part.|bootable|Head Cyl. Sector|System|Head Cyl. Sector| Sector |Sectors  |  MB
-----+--------+----------------+------+----------------+--------+---------+----
1    |    yes |   1    0      1|   06h| 127  519     63|      63|  4193217|2047
2    |     no |   0    0      0|   00h|   0    0      0|       0|        0|   0
3    |     no |   0    0      0|   00h|   0    0      0|       0|        0|   0
4    |     no |   0    0      0|   00h|   0    0      0|       0|        0|   0

Checking root sector ... OK

The size of the drive is reported as 2,063 MB and DOS used 2,047 MB for which it is the maximum that MS-DOS 6.22 can hold per partition. Here's the output of what the boot sector informatio looks like:

Boot sector:

Bytes per sector: 512
Sectors per cluster: 64
Reserved sectors: 1
Number of FATs: 2
Number of rootdirectory entries: 512
Number of sectors (short): 0
Media descriptor byte: F8h
Sectors per FAT: 256
Sectors per track: 63
Drive heads: 128
Hidden sectors: 63
Number of sectors (long): 4193217
Physical drive number: 80h
Signature: 29h

Checking boot sector ... OK
Checking FAT ... OK
Searching for free space ... OK

Because the Point 510 has no floppy drive, I've decided to NOT make a backup copy of the original root and boot sector prior to proceeding.

Prior to splitting the drive, here's what the output is going to look like:

Enter start cylinder for new partition (33 - 519):

Use the cursor keys to choose the cylinder, <enter> to continue

Old partition      Cylinder       New Partition
  129.9 MB             33           1917.6 MB

I want the size of the partitions on the 2.16 GB hard drive to be as even as possible. So, I entered 262 cylinders and a new partition size of 1,015.9 MB. Here's the final output of what it looks like:

Old partition      Cylinder       New Partition
 1031.6 MB           262           1015.9 MB

First Cluster: 33004
Last Cluster: 65511

Testing if empty ... OK

New partition table:

     |        |     Start      |      |      End       | Start  |Number of|
Part.|bootable|Head Cyl. Sector|System|Head Cyl. Sector| Sector |Sectors  |  MB
-----+--------+----------------+------+----------------+--------+---------+----
1    |    yes |   1    0      1|   06h| 127  261     63|      63|  2112705|1031
2    |     no |   0  262      1|   06h| 127  519     63| 2112768|  2080512|1015
3    |     no |   0    0      0|   00h|   0    0      0|       0|        0|   0
4    |     no |   0    0      0|   00h|   0    0      0|       0|        0|   0

Checking root sector ... OK

Do you want to continue or reedit the partition table (c/r)?

If I press C, I get this:

Checking root sector ... OK

Do you want to continue or reedit the partition table (c/r)? c

New boot sector:

Bytes per sector: 512
Sectors per cluster: 64
Reserved sectors: 1
Number of FATs: 2
Number of rootdirectory entries: 512
Number of sectors (short): 0
Media descriptor byte: F8h
Sectors per FAT: 256
Sectors per track: 63
Drive heads: 128
Hidden sectors: 63
Number of sectors (long): 2112705
Physical drive number: 80h
Signature: 29h

Checking boot sector ... OK

Ready to write new partition scheme to disk
Do you want to proceed (y/n)?

If I press R, the process will halt and I will have to start all over again. When FIPS is ready to write the new partition scheme to disk, it asks if it wants to proceed or not. And if I do, I get this:

Repartitioning complete

Bye!

Memory allocation error
Cannot load COMMAND, system halted

After I reboot, I run FDISK, press 4 to display partition information and get this output:

                      Display Partition Information

Current fixed disk drive: 1

Partition  Status   Type    Volume Label  Mbytes   System   Usage
 C: 1         A    PRI DOS                 1032   FAT16       50%
 D: 2              PRI DOS                 1016   UNKNOWN     49%

What's odd is that FIPS, shrank the size of drive C to 1,032 MB and created a unformatted second primary partition, drive D of 1,016 MB. To fix this, I will have to delete the second primary DOS partition and recreate it as a logical DOS drive in the extended DOS partition.

I select option 3 to delete the primary DOS partition and what I want to do is to select the unformatted drive D, prior to doing this, I get this warning:

WARNING! Data in the deleted Primary DOS Partition will be lost.
What primary partition do you want to delete..? [1]

The primary partition that I want to delete is 2, Drive D. I enter the current volume label, which is blank and tells that I'm sure that I want to delete the second primary DOS partition. When that's done, the primary DOS partition gets deleted.

Now, I will need to create a extended DOS partition first and a logical DOS drive in the extended DOS partition by selection option 1 and in Create DOS Partition or Logical DOS Drive, I select 2, Create Extended DOS partition. Here's the output:

                      Create Extended DOS Partition

Current fixed disk drive: 1

Partition  Status   Type    Volume Label  Mbytes   System   Usage
 C: 1         A    PRI DOS                 1032   FAT16       50%


Total disk space is 2063 Mbytes (1 Mbyte = 1048576 bytes)
Maximum space available for partition is 1032 Mbytes (50%)


Enter partition size in Mbytes or percent of disk space (%) to
create an Extended DOS Partition..............................: [1032]

The value 1032 is correct which will split the 2.02 GB partition in two. As a result, an extended DOS partition of 1,032 MB gets created. Now, it's time to create a logical DOS drive in the extended DOS partition. So far, so good. No logical DOS drive have been defined yet. FDISK then asks me this question in this output:

Total Extended DOS Partition size is 1032 Mbytes (1 MByte = 1048576 bytes)
Maximum space available for logical drive is 1032 Mbytes (100%)

Enter logical drive size in Mbytes or percent of disk space (%)...[1032]

This figure is correct, I want FDISK to use all of the extended DOS partition space of 1,032 MB. When I hit enter, drive D gets created. However, FDISK tells me that "all available space in the Extended DOS Partition is assigned to logical drives".

I'm all finished deleting the second primary DOS partition, creating an extended DOS partition and a logical drive in the extended partition. Now, I get to restart.

After I restart, I must format the logical drive and I will end up receiving this warning if I format drive D:

WARNING: ALL DATA ON NON-REMOVABLE DISK
DRIVE D: WILL BE LOST!
Proceed with Format (Y/N)?

The actual formatted capacity of the logical drive, drifve D will be 1,031.59 MB. At 32 KB per cluster, that's 33,006 clusters. Drive C, the boot drive will have 33,002 clusters instead of 65,510.


This procedure was performed in Virtual PC 2004. The real thing was done on the Fujitsu Point 510. When I completed the procedure as described above, the drive letter for the PCMCIA partition was changed from drive D to drive E.

By using FIPS to split the drive into one primary partition and one logical partition in the extended drive, MS-DOS can use all of the disk space this way.

On hard drives that have a capacity greater than 2,048 MB and up to 8,025 MB, the drive will have to be split into multiple partitions as stand alone MS-DOS can't handle drives larger than 2,047 MB.

Also, MS-DOS has no support for hard disks and other media larger than 8,025 MB (including primary and logical DOS partitions), it was released before INT13 extensions were implemented in 1998. There is no fix for this issue as it cannot be corrected by a BIOS upgrade or extension. If a hard disk or other media is found to be larger than 8,025 MB and is partitioned with FDISK, any additional disk space beyond this limit will be truncated.

[rloew]

ppgrainbow, on 29 December 2012 - 07:25 AM, said:

Also, MS-DOS has no support for hard disks and other media larger than 8,025 MB (including primary and logical DOS partitions), it was released before INT13 extensions were implemented in 1998. There is no fix for this issue as it cannot be corrected by a BIOS upgrade or extension. If a hard disk or other media is found to be larger than 8,025 MB and is partitioned with FDISK, any additional disk space beyond this limit will be truncated.

There is a way to use more than 8GB with DOS 6.22. I created a DDO that made a 64GB Hard Drive look like 8 8GB Hard Drives. By careful arrangement, I was able to setup 8 2GB Partitions for DOS 6.22 and DOS 7 as well as 8GB Partitions for DOS 7 only.

[ppgrainbow]

rloew, on 29 December 2012 - 01:45 PM, said:

ppgrainbow, on 29 December 2012 - 07:25 AM, said:

Also, MS-DOS has no support for hard disks and other media larger than 8,025 MB (including primary and logical DOS partitions), it was released before INT13 extensions were implemented in 1998. There is no fix for this issue as it cannot be corrected by a BIOS upgrade or extension. If a hard disk or other media is found to be larger than 8,025 MB and is partitioned with FDISK, any additional disk space beyond this limit will be truncated.

There is a way to use more than 8GB with DOS 6.22. I created a DDO that made a 64GB Hard Drive look like 8 8GB Hard Drives. By careful arrangement, I was able to setup 8 2GB Partitions for DOS 6.22 and DOS 7 as well as 8GB Partitions for DOS 7 only.

Really? How do dynamic drive overlays to get around the 8,025 MB limit work in MS-DOS 6.22?

I created a 16 GB dynamically sized partition under MS-DOS 7.0 by splitting the drive up into one 2,047 MB partition and 7 logical partitions in the extended DOS partition as follows:

                          Display Partition Information
    Current fixed disk drive: 1

    Partition  Status   Type    Volume Label  Mbytes   System   Usage
     C: 1         A    PRI DOS                 2047   FAT16       12%
        2              EXT DOS                14331               87%

FDISK reports that the 16 GB drive has a total disk space capacity of 16,379 MB with 14,331 MB (or 87% of the hard drive) has been allocated to a extended DOS partition containing 7 logical DOS drives. The output are as follows:

                      Display Logical DOS Drive Information

Drv Volume Label  Mbytes  System  Usage
D:                 2047  FAT16      14%
E:                 2047  FAT16      14%
F:                 2047  FAT16      14%
G:                 2047  FAT16      14%
H:                 2047  FAT16      14%
I:                 2047  FAT16      14%
J:                 2047  FAT16      14%

The 7 2 GB partitions actually total 14,329 MB as opposed to 14,331 MB.

All of the partitions of the hard drive larger than 8,025 MB under MS-DOS 7 and MS-DOS 8 are properly recognised.

Under MS-DOS 6.22 guess what happens to the remaining 6,306 MB of disk space on the 16 GB drive?

                          Display Partition Information
    Current fixed disk drive: 1

    Partition  Status   Type    Volume Label  Mbytes   System   Usage
     C: 1         A    PRI DOS                 2047   FAT16       26%
        2              Non-DOS                 1433              100%

The drive capacity of 16,379 MB is reported as 8,025 MB thus truncating the remaining 6,306 MB under MS-DOS 6.22 and below. Also, the logical DOS drives in the extended DOS partition are treated as a non-DOS partition. Any attempts to access drives D through J throw a "invalid drive specification" error message.

Also, under DOS 6.22 and below, there will be no way to access the logical drives in the extended DOS partition without having to delete the non-DOS partition and re-create them. If it is done, the maximum amount of space available for the extended DOS partition will be no more than 5,977 MB.

However, with dynamic drive overlays that are capable of going beyond 8,025 MB. DDOs such as Ontrack Disk Manager version 9.50 and higher can do that. However, there are consequences when creating a hard disk partition larger than 8,025 MB with a DDO for MS-DOS 5.0 through 6.22 - the drive will have to be re-partitioned and formatted, resulting in data loss.

With some DDOs, it will only accept hard disks and other media up to 31.5 GB enough to extend the drive letter all the way up to drive R. MS-DOS 5.0 through 7.0 can't handle hard disks larger than 48 GB due to the 2 GB FAT16 limitation and A to Z drive lettering scheme.

This post has been edited by ppgrainbow: 31 December 2012 - 02:03 AM

[robertcollier4]

ppgrainbow, on 29 December 2012 - 03:17 AM, said:

Well...anyways, I am stumped trying to find a good DOS or Win16 utility that will resize the partition without destroying the data on the hard drive.

PartitionGuru 4.x can resize a partition via its bootable FreeDOS utility bootdisk.
Downoad the full app here:
http://www.eassos.co...ru/download.php

Download just the FreeDOS boot image here for use in a bootloader such as Grub4Dos:
http://sites.google....0FreeDOS.ima.gz

Grub4DOS menu.lst entry:

title PartitionGuru420FreeDOS.ima.gz [inmemory]
map --mem /iso/PartitionGuru420FreeDOS.ima.gz (fd0)
map --hook
root (fd0)
chainloader /kernel.sys

[rloew]

ppgrainbow, on 31 December 2012 - 02:02 AM, said:

Really? How do dynamic drive overlays to get around the 8,025 MB limit work in MS-DOS 6.22?

The DDO makes the Hard Drive appears as a number of smaller Hard Drives.

Quote

However, with dynamic drive overlays that are capable of going beyond 8,025 MB. DDOs such as Ontrack Disk Manager version 9.50 and higher can do that. However, there are consequences when creating a hard disk partition larger than 8,025 MB with a DDO for MS-DOS 5.0 through 6.22 - the drive will have to be re-partitioned and formatted, resulting in data loss.

Some require repartitioning, some don't. The ones that do gave DDOs a bad name.
Either way these DDOs will not help as they are designed for a different purpose. They only add support for Hard Disks larger than the Computer BIOS can support.
They do not split the Disk into smaller parts. I designed my DDO from scratch. I also Patched IO.SYS 6.22 to recognize Type 0xF Partitions.

Quote

With some DDOs, it will only accept hard disks and other media up to 31.5 GB enough to extend the drive letter all the way up to drive R. MS-DOS 5.0 through 7.0 can't handle hard disks larger than 48 GB due to the 2 GB FAT16 limitation and A to Z drive lettering scheme.

The 31.5GB limit is due to some other limitation of the DDO.
True, the limit is 48GB if you stick with conventional formatting. Windows NT formatting allows DOS 6.22 to have 4GB Partitions. I'm sure I can bump that up to 8GB with a few mods.
I actually only used 16 GB for DOS 6.22 leaving the remainder for DOS 7. Combined with a Boot Drive of 8GB, this gave me C: - N:.

[ppgrainbow]

robertcollier4, on 31 December 2012 - 05:00 AM, said:

ppgrainbow, on 29 December 2012 - 03:17 AM, said:

Well...anyways, I am stumped trying to find a good DOS or Win16 utility that will resize the partition without destroying the data on the hard drive.

PartitionGuru 4.x can resize a partition via its bootable FreeDOS utility bootdisk.
Downoad the full app here:
http://www.eassos.co...ru/download.php

Download just the FreeDOS boot image here for use in a bootloader such as Grub4Dos:
http://sites.google....0FreeDOS.ima.gz

Grub4DOS menu.lst entry:

title PartitionGuru420FreeDOS.ima.gz [inmemory]
map --mem /iso/PartitionGuru420FreeDOS.ima.gz (fd0)
map --hook
root (fd0)
chainloader /kernel.sys

I already split the drive in half using FIPS and created a logical drive in the DOS partition using FDISK. Thanks for the help, btw. I should also try that with with a MS-DOS boot image for use in a bootloader also.

[ppgrainbow]

I tested a 4,000 MB partition under Windows NT 4.0 and when MS-DOS attempted to access a hard disk that large, the size of the files on that drive got truncated to zero. Any attempts to format a whole partition larger than 2 GB results in a Divide Overflow error and the process can't continue.

Also, how did you patch IO.SYS in MS-DOS 6.22 to recognise Type 0x0F partitions which were first introduced in MS-DOS 7? I'm also wondering if there is a way for DOS 6.22 to recognise Type 0x0E partitions with FAT16X support also?

I presume that unofficially, the largest drive that MS-DOS 6.22 can accept with the patched IO.SYS is up to 32 GB due to data corruption concerns.

[rloew]

ppgrainbow, on 31 December 2012 - 05:57 PM, said:

I tested a 4,000 MB partition under Windows NT 4.0 and when MS-DOS attempted to access a hard disk that large, the size of the files on that drive got truncated to zero. Any attempts to format a whole partition larger than 2 GB results in a Divide Overflow error and the process can't continue.

I ran some tests. I did not see any data corruption. CHKDSK will report corruption. DOS SCANDISK with not run. Windows ME SCANDISK shows no corruption.
Some utilities will think there is no free disk space such as DIR and DEBUG.
I used my own Formatter (RFORMAT) to format the Partition.

Quote

Also, how did you patch IO.SYS in MS-DOS 6.22 to recognise Type 0x0F partitions which were first introduced in MS-DOS 7? I'm also wondering if there is a way for DOS 6.22 to recognise Type 0x0E partitions with FAT16X support also?

I patched it to think that a type 0xF Partition was a Type 5 Partition. There is no need to recognize Type 0xE Partitions unless you need multiple Primary Partitions in DOS 7.

Quote

I presume that unofficially, the largest drive that MS-DOS 6.22 can accept with the patched IO.SYS is up to 32 GB due to data corruption concerns.

With my existing Patches, 48GB is the limit, for all normal Partitions combined, due to Drive Letter limits.
The limit is 96GB with the NT Format, 94GB if booted from the C: Partition.
If I ported all of my Terabyte Plus Patches from DOS 7 to DOS 6.22, and wrote a new DDO, the limit could be pushed to between 8TB and 12TB.

This post has been edited by rloew: 31 December 2012 - 09:34 PM

[ppgrainbow]

rloew, on 31 December 2012 - 09:33 PM, said:

ppgrainbow, on 31 December 2012 - 05:57 PM, said:

I tested a 4,000 MB partition under Windows NT 4.0 and when MS-DOS attempted to access a hard disk that large, the size of the files on that drive got truncated to zero. Any attempts to format a whole partition larger than 2 GB results in a Divide Overflow error and the process can't continue.

I ran some tests. I did not see any data corruption. CHKDSK will report corruption. DOS SCANDISK with not run. Windows ME SCANDISK shows no corruption.
Some utilities will think there is no free disk space such as DIR and DEBUG.
I used my own Formatter (RFORMAT) to format the Partition.

Quote

Also, how did you patch IO.SYS in MS-DOS 6.22 to recognise Type 0x0F partitions which were first introduced in MS-DOS 7? I'm also wondering if there is a way for DOS 6.22 to recognise Type 0x0E partitions with FAT16X support also?

I patched it to think that a type 0xF Partition was a Type 5 Partition. There is no need to recognize Type 0xE Partitions unless you need multiple Primary Partitions in DOS 7.

Quote

I presume that unofficially, the largest drive that MS-DOS 6.22 can accept with the patched IO.SYS is up to 32 GB due to data corruption concerns.

With my existing Patches, 48GB is the limit, for all normal Partitions combined, due to Drive Letter limits.
The limit is 96GB with the NT Format, 94GB if booted from the C: Partition.
If I ported all of my Terabyte Plus Patches from DOS 7 to DOS 6.22, and wrote a new DDO, the limit could be pushed to between 8TB and 12TB.

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

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? 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?

Or is that something different here...

[rloew]

ppgrainbow, on 01 January 2013 - 04:15 PM, said:

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.

Quote

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.

Quote

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.

This post has been edited by rloew: 01 January 2013 - 06:18 PM

[ppgrainbow]

rloew, on 01 January 2013 - 06:17 PM, said:

ppgrainbow, on 01 January 2013 - 04:15 PM, said:

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.

Quote

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.

Quote

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.

[rloew]

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.

[ppgrainbow]

rloew, on 01 January 2013 - 09:55 PM, said:

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.

This post has been edited by ppgrainbow: 02 January 2013 - 09:56 PM

[rloew]

ppgrainbow, on 02 January 2013 - 09:55 PM, said:

rloew, on 01 January 2013 - 09:55 PM, said:

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.

[ppgrainbow]

rloew, on 02 January 2013 - 10:51 PM, said:

ppgrainbow, on 02 January 2013 - 09:55 PM, said:

rloew, on 01 January 2013 - 09:55 PM, said:

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.