1 | BIOS LIMITATIONS
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2 | ----------------
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3 | Included here are brief explanations of a number of drive capacity
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4 | limitations that exist in the computer industry. The use of Disk Manager
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5 | and its Dynamic Drive Overlay offers a solution to each of these problems.
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6 |
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7 | *** 528 MB Limitation ***
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8 |
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9 | Using the traditional IDE interface limits the system to a maximum drive
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10 | capacity of 528 MB. The cause of this limitation is Int 13h (BIOS) and
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11 | IDE field sizes for the CHS (Cylinder, Head, and Sector) entries.
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12 |
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13 | Because the system must perform a translation between the CHS parameters
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14 | recognized by the drive and those established in the Int 13h code,
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15 | parameters are limited to the smaller of the field sizes allowed for
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16 | each parameter by the BIOS and the IDE register set. The chart below
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17 | displays the BIOS, IDE, and limiting field size.
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18 |
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19 | BIOS IDE Limit
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20 | Sectors per Track 63 255 63
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21 | Number of Heads 255 16 16
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22 | Number of Cylinders 1024 65536 1024
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23 | ------ -------- ------
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24 | Maximum Capacity 8.4 GB 136.9 GB 528 MB
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25 |
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26 | The maximum system drive capacity in a combined BIOS/IDE setup is
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27 | determined by the limiting field size -- 528 MB. Currently, computers
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28 | are being shipped with a BIOS that implements Extended Int 13h or
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29 | "Logical Block Addressing" (LBA), both of which are solutions to the
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30 | 528 MB limitation.
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31 |
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32 | *** 4096 Cylinder (2.1 GB) Limitation ***
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33 |
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34 | Some computers have a BIOS that does not properly deal with the "13th
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35 | bit". The 13th bit is needed to provide support for a drive having
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36 | 4096 or more cylinders. The chart below displays the corresponding
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37 | cylinder values in decimal, hex, and binary values.
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38 |
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39 | DECIMAL HEX BINARY SIZE
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40 | 1023 = 3FF = 10 bits = 528 MB
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41 | 2047 = 7FF = 11 bits = 1.0 GB
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42 | 4095 = FFF = 12 bits = 2.1 GB
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43 | 8191 = 1FFF = 13 bits = 4.2 GB
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44 | 16383 = 3FFF = 14 bits = 8.4 GB
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45 |
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46 | If you have added a new drive and your system locks up at boot time
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47 | (right after turning power on) or during System Setup, there may be
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48 | several causes. Verify that the data cable is properly attached to your
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49 | drive, pin 1 is correct, and the cable is not installed off a row of pins.
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50 | If your new drive is larger than 2.1GB and your System Setup (CMOS) is
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51 | set to "AUTO", you may have a BIOS with a 4096 or greater cylinder
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52 | limitation. In this case, power off your system, remove your new drive,
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53 | and follow the instructions that DiskGo! provides. When configuring
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54 | System Setup (CMOS), DO NOT USE AUTO. Rather, choose one of the
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55 | following:
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56 | - USER DEFINABLE set to 1024 cyls 16 hds 63 sects
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57 | - Drive type 1.
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58 | Another option is to contact your computer manufacturer to get a BIOS
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59 | upgrade that will support more than 4096 cylinders.
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60 |
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61 | *** 6322 Cylinder (3.27 GB) Limitation ***
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62 |
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63 | Some computers have a BIOS that does not properly handle a cylinder value
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64 | over 6322. If you are in the System Setup attempting to set the cylinder
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65 | value higher than 6322 (for a 3.27 GB+ drive) and your computer hangs,
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66 | your computer may have a BIOS with this limitation. To by-pass this
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67 | limitation, you have two options:
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68 | - Set the cylinder value to 1024 or less and use Ontrack's Disk
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69 | Manager to provide support for the whole drive.
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70 | - Contact your computer manufacturer for a BIOS upgrade, if one is
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71 | available.
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72 |
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73 | *** Invalid BIOS information ***
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74 |
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75 | Some computers have a BIOS that may display invalid information in the
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76 | System Setup (CMOS). This issue may show up in one of two ways:
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77 | - The System Setup will display the drive parameters and capacity
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78 | correctly. However, it is not translating the drive correctly.
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79 | - The System Setup will display invalid drive parameters. However,
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80 | the BIOS is translating the drive correctly.
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81 | To ensure your drive is translated to its full capacity, you
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82 | will need to check the actual drive size. This can be done when creating
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83 | partitions on the drive.
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84 |
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85 | *** 8.4 Gigabyte limit ***
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86 | If your drive is larger than 8.4 Gigabytes, the capacity may exceed the
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87 | limits of your system BIOS and operating system. Most system BIOS cannot
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88 | support ATA drives this large. DOS and Windows operating systems limit the
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89 | drive capacity to 8.4 Gigabytes per physical drive and 2 Gigabytes per
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90 | partition.
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91 | Because of these limitations, a 32-bit file allocation table (FAT32) is
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92 | required to achieve full capacity of your drive beyond 8.4 Gigabytes.
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93 | To achieve full capacity of your drive you need a Windows operating system
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94 | that supports FAT32 and BIOS support for drives greater than 8.4 Gigabytes,
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95 | from one of the following:
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96 | Third party device driver, such as Disk Manager (Disk Manager is provided
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97 | on the DiskGo! diskette included with your drive), or an intelligent ATA
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98 | host adapter, or a system BIOS upgrade.
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99 |
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100 | *************************************************************************
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101 | *************************************************************************
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102 |
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103 | To install your hard disk using Disk Manager, simply follow these
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104 | basic steps:
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105 |
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106 | 1) Following the instructions that DiskGo! provides you,
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107 | set your System Setup (CMOS), jumper your drive(s), and
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108 | physically install your hard disk into your computer.
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109 | Disk Manager assumes power, cables, jumpers, etc.,
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110 | are connected and properly installed.
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111 |
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112 | 2) Insert your DOS diskette in drive A: and boot the machine
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113 | to DOS.
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114 |
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115 | 3) Insert your DiskGo! diskette into drive A: and
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116 | type DM to invoke Disk Manager.
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117 |
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118 | 4) When the installation has completed, remove the DiskGo!
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119 | diskette from drive A: and boot from the hard disk.
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120 |
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121 | See the Disk Manager online manual for more information.
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122 |
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123 | Refer to the License Agreement at the beginning of the DiskGo!
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124 | program.
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125 |
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126 | Disk Manager is copyright 1985-1999 by ONTRACK Data International, Inc.
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127 | Refer to the License Agreement in the Disk Manager online manual.
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