====== Third-Party Optical Drive Support ======

===== What is this mod for? =====

System 7, OS 8, and OS 9 use custom CD/DVD drivers that will normally only work with specific optical drives. While there has been third-party software in the past to support other drives, there are a lot of models found on eBay and elsewhere that still aren't supported.

Fortunately, there's a very simple edit that can be made to the operating system's native CD/DVD driver to support just about any optical drive you can find.

===== Required tools =====

This modification requires%% %%ResEdit%% %%or another resource editor (although ResEdit is free, so that's probably your best option).

You also need to identify what version of the Apple CD/DVD driver you have installed. The easiest way to find this in OS 8 or OS 9 is to use System Profiler. In System 7, it's a little bit harder. You can try something like%% %%TattleTale%% %%or%% %%Tech Tool Pro%% %%to get the version of your driver.

The following driver versions support this mod:

  * CD-ROM 5.4.2
  * CD/DVD Driver 1.0.1
  * CD/DVD Driver 1.2
  * CD/DVD Driver 1.2.2
  * CD/DVD Driver 1.3.1
  * CD/DVD Driver 1.3.5
  * CD/DVD Driver 1.4
  * CD/DVD Driver 1.4.3

//Please note: driver versions 1.3.1 and higher use the same values for the mod.//

===== Mod instructions =====

**First, make a backup of the system extension!!**%% %%You'll be working on a copy of%% %%**Apple CD-ROM**%% %%or%% %%**Apple CD/DVD Driver**%% %%found in your Extensions folder.

Open a copy of the driver in ResEdit. Look for the resource icon titled%% %%**DRVR**%% %%and double-click it to open.

In the window that appears, select%% %%**ID 32**%% %%and select%% %%**Open using Hex Editor**%% %%from the%% %%**Resource**%% %%menu item.

In this window, use%% %%**Find > Offset**, or%% %%**Cmd+H**%% %%to navigate to the appropriate offset listed in the table below. You will need to change the value of the offset as shown:

^  ''Driver Version''  ^  ''Row''  ^  ''Offset''  ^  ''Original Value''  ^  ''New Value''  ^
|  ''5.4.2''  |  ''06B0''  |  ''06B6''  |  ''6704''  |  ''4E71''  |
|  ''1.01''  |  ''06C8''  |  ''06C8''  |  ''6704''  |  ''4E71''  |
|  ''1.2''  |  ''06C0''  |  ''06C6''  |  ''6706''  |  ''4E71''  |
|  ''1.2.2''  |  ''06D8''  |  ''06D8''  |  ''6706''  |  ''4E71''  |
|  ''1.3.1+''  |  ''06D0''  |  ''06D6''  |  ''6706''  |  ''4E71''  |

Once you've made the above change, save the file and then proceed to the next offset and make the listed change:

^  ''Driver Version''  ^  ''Row''  ^  ''Offset''  ^  ''Original Value''  ^  ''New Value''  ^
|  ''5.4.2''  |  ''09C0''  |  ''09C6''  |  ''6606 4A84 6700 0086''  |  ''4E71 4E71 4E71 4E71''  |
|  ''1.01''  |  ''0A10''  |  ''0A10''  |  ''6606 4A84 6700 0086''  |  ''4E71 4E71 4E71 4E71''  |
|  ''1.2''  |  ''0AD0''  |  ''0AD6''  |  ''6604 4A84 6706''  |  ''4E71 4E71 4E71''  |
|  ''1.2.2''  |  ''0AE8''  |  ''0AE8''  |  ''6604 4A84 6706''  |  ''4E71 4E71 4E71''  |
|  ''1.3.1+''  |  ''0AE0''  |  ''0AE6''  |  ''6604 4A84 6706''  |  ''4E71 4E71 4E71''  |

Save again. Make sure that the modified extension is in your Extensions folder - not the original - and reboot. Your "unsupported" drive should work now!