26 votes
Accepted

When was the CHS (cylinder - head - sector) system invented and what was before it?

It seems the question is mixing up physical disk access (CHS) with a logical access scheme used at a higher level. LBA is and always has been an issue at the OS level. The fact that some disk ...
Raffzahn's user avatar
  • 223k
22 votes
Accepted

How did Drive Overlay programs break BIOS disk barriers on older PCs?

The reference for this is DEW Associates’ pages on the topic. Multiple barriers have existed in the history of hard drives on PC compatibles. The main ones are the barriers at 528 MB (504 MiB) barrier,...
Stephen Kitt's user avatar
19 votes
Accepted

Default (as opposed to physical) read/write heads - what are they?

The physical geometry how many heads the drive actually has is not the same as the logical geometry of how many heads is presented to the PC by the drive. By translating the geometry, the drive can be ...
Justme's user avatar
  • 32.1k
16 votes
Accepted

How can the number of cylinders supported by a floppy drive be different from the number of tracks?

As far as I can tell, the first edition of the IBM 5150 Technical Reference is the only IBM manual which mentions 45 cylinders. Few Technical References document the FDC, which is where the “45 ...
Stephen Kitt's user avatar
15 votes

When was the CHS (cylinder - head - sector) system invented and what was before it?

The cylinder number determines the position the read-write head write must move to, the head number determines which of the multiple read-write heads the disk drive should use, and the sector number ...
dirkt's user avatar
  • 27.3k
15 votes
Accepted

Hard coded hard drive BIOS geometries

The tables were built using the parameters for various real hard drives. For example, type 1 is used for the original Shugart drives used in the PC XT (ST506). So the intention was for the drive types ...
Stephen Kitt's user avatar
14 votes
Accepted

Can DOS 6.22 recognize more than 504MB when the BIOS only supports CHS?

It can be done using a third-party "disk manager", such as OnTrack Disk Manager and EZ-Drive. At the end of the DOS era, these came bundled with many hard disks. https://en.wikipedia.org/wiki/...
Liam Proven's user avatar
  • 1,175
13 votes
Accepted

How can I edit CMOS hard drive geometry settings on a 1991 PC?

In all the BIOS setups I was dealing with that have similarly 47 drives to chose from the first or the last one was editable directly in BIOS SETUP for manual settings. Sometimes the manual settings ...
Spektre's user avatar
  • 7,288
13 votes
Accepted

Why is QEMU cutting off the last cylinder of the disk image?

QEMU is not at fault here. The discrepancy comes from the BIOS. When I create a disk image as described in the question, then attach it to a QEMU virtual machine and use the info qtree command in the ...
user3840170's user avatar
  • 23.1k
13 votes

How to determine BIOS-provided (INT 13h) hard disk geometry, and how to fix the MBR partition table to agree with it?

If you can manage to boot the computer from a DOS floppy or some other device, you should be able to use the classic partitioning tool, Ranish Partition Manager. (I recommend version 2.40 or 2.44; ...
user3840170's user avatar
  • 23.1k
12 votes

Can Linux boot beyond 1023 cylinders on old BIOS?

As the large disk howto explains, LILO bootstraps through a loader that still uses the BIOS, this is why LILO didn't work for you. On the other hand, nuni does not use BIOS services but accesses IDE ...
dirkt's user avatar
  • 27.3k
12 votes
Accepted

Booting from SD card on a Compaq LTE 4/75 – DOS 6 works, Windows 95 doesn't

The problem is in the geometry. Not in the physical disk geometry, but rather in the translation how the BIOS must translate the geometry for DOS when using disks larger than 1024 cylinders. The ...
Justme's user avatar
  • 32.1k
11 votes

How can I tell if my old PC supports > 137 GB hard drives?

Very briefly: The way harddisks are addressed changed over time. Originally, you'd specify cylinder/head/sector (CHS), then it switched to logical block addresses (LBA), and the commands for those ...
dirkt's user avatar
  • 27.3k
10 votes

Default (as opposed to physical) read/write heads - what are they?

Modern hard drives are not addressed by Cylinder, Head and Sector (CHS) coordinates, but by Linear Block Address (LBA). This is mostly due to the number of sectors per track changing across the width ...
Chromatix's user avatar
  • 16.8k
9 votes

How can the number of cylinders supported by a floppy drive be different from the number of tracks?

Floppy disk drives could usually mechanically access more than 40 tracks, but only 40 were actually used, "formatted". First track is on the outer edge of the disk, there is a detector than ...
Grabul's user avatar
  • 3,657
9 votes

How can I make an 80 GB hard drive work with an Asus P2L97 motherboard?

You need a BIOS update. Version 1009 from November 1999 already fixes it according to release notes. It is the final official BIOS version and newer beta releases exist, but must be chosen carefully ...
Justme's user avatar
  • 32.1k
8 votes

Can Linux boot beyond 1023 cylinders on old BIOS?

LILO only requires the /boot partition to be within the area accessible by the BIOS. AFAIK there is no technical reason to not have /boot, on a FAT partition, so you could have a symbolic link from /...
Michael Karcher's user avatar
6 votes

When was the CHS (cylinder - head - sector) system invented and what was before it?

So the question is how the blocks of data were really addressed in old HDDs? Did they make use of CHS or some other system? They used cylinder number. Maybe also head number (i.e., disk platter ...
davidbak's user avatar
  • 6,269
6 votes

How to determine BIOS-provided (INT 13h) hard disk geometry, and how to fix the MBR partition table to agree with it?

There are various different methods of converting the drive physical geometry to logical BIOS geometry. It sounds like the drive was originally been used with "ECHS" or "Large" ...
Justme's user avatar
  • 32.1k
6 votes

Booting from SD card on a Compaq LTE 4/75 – DOS 6 works, Windows 95 doesn't

Whew, I've got it solved! I took one of the disk images with Windows 95 installed on it, and examined it with a hex editor. I noticed that when the Windows installer program initially sets up the ...
Dmitry Brant's user avatar
6 votes

How can I tell if my old PC supports > 137 GB hard drives?

That BIOS screen clearly says that it detects the drive as roughly 8 GB. The parameters say 16383/16/63 as so this BIOS cannot detect or provide the extended disk services that would allow the drive ...
Justme's user avatar
  • 32.1k
4 votes

Compaq Contura Aero 4/33C - moving data to CF/IDE disk - No operating system detected

Because these drives have different geometries and multiple partitions, you can't dd the whole thing in one pass and expect everything to work. In particular, your DOS partitition which was located ...
Ken Gober's user avatar
  • 11.4k
4 votes

Default (as opposed to physical) read/write heads - what are they?

Some older computers used to identify 512-byte sectors by specifying a combination of a head number, sector number, and cylinder number. For historical reasons, the head number was often limited to ...
supercat's user avatar
  • 36.2k
4 votes

How can I make an 80 GB hard drive work with an Asus P2L97 motherboard?

With the upgraded BIOS, the asker’s computer seems to have locked up in a pretty curious moment. This gave me an idea what might be the cause, so I decided to take a stab at disassembling the BIOS to ...
user3840170's user avatar
  • 23.1k
4 votes
Accepted

How can I make an 80 GB hard drive work with an Asus P2L97 motherboard?

Solved by reducing the HDD capacity to 33.82GB with OnTrack Disk Manager 9.57 on floppy disk (Advanced option > Maintenance Option > Utilities > Set Drive Size). It works! (I have another ...
Damien Yearwing's user avatar
4 votes

Can Linux boot beyond 1023 cylinders on old BIOS?

We can make this work. Have a floppy disk that can boot the linux on your hard disk, either using lilo or syslinux to load kernel from floppy disk. Make sure you have access to the boot command ...
Joshua's user avatar
  • 1,829
3 votes

How can I make an 80 GB hard drive work with an Asus P2L97 motherboard?

If installation is your issue, OnTrack Disk Manager 9.57 is available as a bootable disk image. You could just boot your Pentium 2 off its install disk and let it do the rest. Alternatively, if you ...
ssokolow's user avatar
  • 6,765
3 votes

Can Linux boot beyond 1023 cylinders on old BIOS?

Just use loadlin from within the DOS partition which is within the BIOS accessible area of the disk, or shrink the DOS partition and create a small /boot partition that is within 1023 cylinders. If ...
Alex Cannon's user avatar
2 votes

When was the CHS (cylinder - head - sector) system invented and what was before it?

Q: When was the CHS (cylinder - head - sector) system invented . . .? Patent 3,503,060 for a DIRECT ACCESS MAGNETIC DISC STORAGE DEVICE. Original Filed Dec. 24, 1954. Q: . . . and what was before it? ...
Rick Smith's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible