The Enhanced IDE/Fast-ATA FAQ

John Wehman (`jwehman@got.net`) and Peter den Haan (`pieterh@sci.kun.nl`)

v1.91, 1997/01/23

This FAQ addresses issues surrounding Enhanced IDE, ATA-2, ATAPI and Enhanced BIOSes. It includes practical questions, background information and lists of net resources.

1. First off...

2. Introduction

2.1 EIDE and Fast-ATA

2.2 IDE and ATA

2.3 ATA-2

2.4 ATA-3

2.5 ATA Packet Interface

2.6 Ultra-ATA

2.7 ATA-4

2.8 The Enhanced BIOS

2.9 The secondary port and beyond

3. General questions

3.1 What are the main features of EIDE and Fast-ATA?

3.2 Are those rumors about buggy interfaces true?

3.3 What is a megabyte?

4. Before buying...

4.1 What should I look for in an ATA-2 (Fast-ATA, EIDE) interface?

4.2 Is my BIOS Enhanced? How can I recognize this?

4.3 Is my 50MHz VL bus system compatible with ATA-2 interfaces?

4.4 Are old IDE drives compatible with ATA-2 (EIDE) interfaces?

4.5 Can I use EIDE and Fast-ATA drives with my old IDE interface?

4.6 Will an ATAPI (EIDE) CD-ROM work with an IDE interface?

4.7 Do I need a BIOS update to connect an ATAPI CD-ROM?

4.8 Can large drives be used with my old BIOS?

4.9 I need an Enhanced BIOS to access >504MB. How do I get one?

4.10 Can I use a large harddisk with OSs other than DOS/Windows?

4.11 I heard that Win95 provides support for large IDE disks.

4.12 Can I use more than 2 or 4 hard drives?

4.13 Does <insert operating system> support ATAPI (IDE) CD-ROMs?

4.14 I need a PCI ATA-2 interface that uses only one slot.

4.15 Will adding an 'EIDE' interface help my drives' performance?

5. Installation

5.1 Which drive/device should be Slave?

5.2 Does it matter how I connect the devices to the cable?

5.3 Does an old HD or CDROM slow down a new drive?

5.4 I need a longer IDE cable; how long can I make it?

5.5 Can I safely move my harddisk between computers?

6. Configuration

6.1 Should I use my interface's device drivers?

6.2 What should I use: Normal, LBA or Large?

6.3 Can I safely change the BIOS' xlation mode (None, LBA, Large)?

6.4 Should I enable EIDE busmastering in my BIOS?

6.5 `FDISK` sees only 504MB of my disk!

6.6 `FDISK` will partition only 2GB.

6.7 I have no fancy EBIOS, but I have an 1GB partition and it works.

6.8 I have software to break the 504MB barrier. Should I use it?

6.9 Can I keep my Disk Manager/EZDrive partition with a new BIOS?

6.10 I need to remove Disk Manager/EZDrive.

6.11 I can enable write caching on my harddisk. Should I?

6.12 My drive letters have changed!

7. Performance

7.1 Why isn't my drive as fast as it's advertised to be?

7.2 Why is my new EIDE interface no faster than my old VLB one?

7.3 I benchmarked my drive and it's getting slower!

7.4 A guy on the net has the same drive and he gets 16MB/s!

7.5 Busmastering drivers don't do much...

8. Troubleshooting

8.1 Why do I get `NO ROM BASIC, SYSTEM HALTED`?

8.2 I have problems with my Award 4.50G BIOS and large drives.

8.3 My 2GB+ drive is not recognized or crashes.

8.4 My 4GB+ drive has problems in MSDOS 6.22 or below.

8.5 Help! I have OnTrack Disk Manager installed and now...

8.6 My mode 3-4-5-6 drive has data corruption problems.

8.7 Are there supposed to be bad sectors on the drive?

8.8 I keep getting CRC errors and serial overruns.

8.9 Can my drive do 32-bit access?

8.10 Help! Windows 3.x 32-bit disk access doesn't work anymore!

8.11 Help! Windows for Workgroups' 32-bit file access fails!

8.12 Help! Win95 indicates my drive uses compatibility mode!

8.13 My partitions become a mess in MS-DOS mode.

8.14 Win95 sees my partitions, but DOS doesn't.

8.15 Win95 keeps losing my second IDE channel!

8.16 The Win95 busmastering drivers won't work.

8.17 My ATAPI (IDE) CD-ROM driver won't recognize the CD-ROM.

9. The user's net.resource guide

9.1 The user's net.resource guide: I/O card drivers

9.2 The user's net.resource guide: hardware manufacturers

9.3 The user's net.resource guide: software and BIOS houses

10. ATA: harddisks

10.1 How does ATA(-2) work?

10.2 What are PIO modes?

10.3 What are DMA modes?

10.4 How are the ATA(-2,PI) I/O ports assigned?

10.5 What does an ATA-2 interface do?

10.6 What is Block mode?

10.7 What is LBA?

10.8 How does security work?

10.9 What is S.M.A.R.T.?

10.10 What is PRML?

10.11 What are MR heads?

11. ATAPI: CD-ROMs and tapes

11.1 How does ATAPI differ from, and coexist with, ATA(-2)?

11.2 What's so special about the secondary port?

12. The EBIOS: translation

12.1 Why translation?

12.2 How does translation work?

12.3 I'd like to know how translation works in detail.

12.4 What is in the Enhanced Disk Parameter Table?

12.5 How many types of translating/Enhanced BIOSes are there?

13. Software details

13.1 Details on OnTrack Disk Manager

13.2 How does Windows' 32-bit disk access work?

14. Hacker's resource guides

14.1 The hacker's documentation guide

14.2 The hacker's net.resource guide