ASPI setup instructions

1. Introduction

WinDAC32 works better if an ASPI (Advanced SCSI Programming Interface) manager is installed. Now you may think: "I'm using only ATAPI devices, why i have to use a SCSI Programming Interface?". The answer is simple: Windows 95 and NT are both internally working only with SCSI devices and all devices has to be accessed through a SCSI miniport driver, even if they are SCSI or not. So the miniport drivers are responsible to convert the commands send by Windows to the commands expected by the drive. For ATAPI devices this is really simple, because they are using nearly the same command set as specified in the SCSI Specification only with a differnt protocol.

2. Installation of the ASPI manager

Since this differs depending on the used Windows Version i will describe the following in different sections

2.1 Windows 95

Normally there is no need to install an ASPI manager for Windows 95 because it installs its own (an old version from Adaptec). The default ASPI manager works fine with SCSI and ATAPI drives and should be enough for most purposes. But sometimes you may wish to install an updated version of an ASPI manager, because you have found some problems or bugs (i found only one bug and this doesn't seem to cause any problems). In this case you can look for a newer version. The only company offering ASPI drivers for Win95 seems to be Adaptec so have a look at their homepage for updates. These Updates won't install without an installed Adaptec host adapter or Adaptec software, but you can simply install a Windows driver for a non PnP SCSI Controller like the 1505 included in Win9x and activate it even you don't have such a Adapter. After that you should be able to install the update.

2.2 Windows NT

Unfortunately Microsoft doesn't supply an ASPI manager with Windows NT up to version 4.0 (and even not with the service packs and in the current Windows 2000 beta version). So you have to find an ASPI manager for NT. For NT not only Adaptec is offering an ASPI manager, even Symbios Logic or Mylex habe their own versions (I'm not sure about the Mylex one, it is only a DLL without any System driver). Even the Adaptec CD-Writing programs are installing a current version of their ASPI manager.

3. ASPI setup

If WinDAC32 couldn't detect ATAPI devices after ASPI manager setup or update, you have to change the configuration of the ASPI manager.

3.1 Windows 95

Here you have two options to make the ASPI manager work with ATAPI devices again.
The first option to to downgrade to the original Win95 ASPI manager by copying the following files from the Win95 CAB files:

WNASPI32.DLL -> WIN\SYSTEM
WINASPI.DLl  -> WIN\SYSTEM
APIX.VXD     -> WIN\SYSTEM\IOSUBSYS
ASPI2HLP.SYS -> WIN

The second option is much more simple. Open the registry editor and open the key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\APIX
If it doesn't exist create it and after that create the following entry:
ExcludeMiniports=""
You can also use the following Reg file to do this, simple download it and make a double click on it.

3.2 Windows NT

Since there is no default ASPI manager you can not downgrade to an older version like in Win95. But even her it is posible to change the setup by adding entries in the registry:
Open the registry editor of Windows NT and open the key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ASPI32\Parameters
If it doesn't exist create it and after that create the following entry:
ExcludeMiniports=""
You can also use the following Reg file to do this, simple download it and make a double click on it.