Questions tagged [chs]

Cylinder-head-sector disk addressing: addressable range, direct use, compatibility issues and conversion between coordinate systems.

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18 votes
1 answer

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

I was just reading a thread on Vogons about OnTrack and EZ-Drive setup, and it occurred to me that I have no idea how they work. Please explain why the barrier existed and then how the overlay ...
Thraka's user avatar
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13 votes
4 answers

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

There is some information about the CHS (Cylinder/Head/Sector) addressing system and its design flaws and limits. As long as CHS was not compatible with Zone Bit Recording, which became very popular ...
Vitaly Isaev's user avatar
13 votes
2 answers

Hard coded hard drive BIOS geometries

Most old BIOSes on PCs and compatibles provided means to enter hard drive geometries (cylinder/head/sector as well as more esoteric things like write precomp) when configuring the machine. Some (AMI ...
Joe's user avatar
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12 votes
1 answer

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

I made a new disk image with the command dd if=/dev/zero of=hd.img bs=512 count=$(expr 16 \* 63 \* \( 15 \* 16 + 8 \)) which corresponds to creating a disk that would fill exactly with QEMU's default ...
Joshua's user avatar
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11 votes
3 answers

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

The Seagate U Series hard disk Product manual states that the drive has 16 "Default read/write heads" while it has 4/3/2/1 "Physical read/write heads" (depending on actual model). ...
Dercsár's user avatar
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11 votes
1 answer

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

First, I am NOT asking how to use the BIOS Setup utility. I'm asking how to OVERRIDE the built-in settings my BIOS Setup supports for the HD geometry. I have a 1991 NCR PC with a 386SX, on-board IDE, ...
Brian H's user avatar
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10 votes
2 answers

How can the number of cylinders be different from the number of tracks?

In the IBM PC 5150 documentation, it is stated that the floppy drive has 40 tracks, 8 sectors/track and 512 bytes/sectors, for a total of 163 840 bytes of data. It makes sense, 40×8×512 = 163 840 ...
Adrien's user avatar
  • 203
9 votes
2 answers

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

When transferring a hard drive from one computer to another, sometimes a situation can occur where the BIOS-provided CHS hard disk geometry (interrupt 13h without extensions) is different from the CHS ...
Alex Cannon's user avatar
8 votes
2 answers

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

I've got a Compaq Contura Aero 4/33 laptop with original DOS system installed. As the HDD is old and dying, I've decided to copy the drive to a CF card on a CF/IDE adapter. After connecting the drive, ...
user905747's user avatar
7 votes
2 answers

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

My CMOS setup correctly recognizes the geometry of the drive, (but does not support LBA). And FDISK in DOS 6.22 only recognizes 504MB. FDISK even shows the size of the primary partition as roughly ...
Quasi_Stomach's user avatar
7 votes
4 answers

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

I'm in the process of restoring an old Compaq LTE Elite 4/75 laptop, which was missing its hard drive, so I thought I'd try booting using an SD-to-IDE adapter. On my main workstation I created an ...
Dmitry Brant's user avatar
7 votes
3 answers

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

I have an old PC from 1999 that has an ASUS P5A motherboard. When I power it on, it says ASUS P5A ACPI BIOS Revision 1011 Beta 005 and 05/02/2002-ALADDIN5-<<P5A>>: I recently read that up ...
pacoverflow's user avatar
3 votes
4 answers

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

I have a 80 GB PATA HDD (2003 Western Digital Caviar WD800 LBA) which is not recognized by my very old computer (Pentium 2 / Asus P2L97 motherboard). I thought it was due to the partitioning of the ...
Damien Yearwing's user avatar