DOS Wiki

The BLASTER variable is a DOS environment variable that most DOS programs use to locate and identify a SoundBlaster (or compatible) soundcard. The BLASTER variable consists of 4 mandatory parts, as well as a couple of optional parts. An example of a basic BLASTER setting is:

A220 I7 D1 T6

This setting can be broken down as follows:

  • A220 - This is the memory address port at which the SoundBlaster card is located. Possible values include A220 (typical), A240, A260, and A280.
  • I7 - This is the IRQ that the sound card uses. This will probably be 5 or 7.
  • D1 - This the DMA channel. Although several DMA channels can be used, 1 is the most common and likely to work.
  • T6 - This the sound card type. T1 is an original SoundBlaster, T2 is an SoundBlaster 1.5, T3 is an SoundBlaster 2, T4 is an SB Pro, T5 is an SB Pro with an FM Synthesis chip, and T6 is an SoundBlaster 16 or later.

Extended options for the BLASTER variable also exist. These do thing like control MIDI, a second DMA channel, and indicate the card type. An extended BLASTER variable will look something like:

A220 I7 D1 T6 P330 H5

  • P330 - MIDI address port. Possible values are P300 and P330 (typical).
  • H5 - High DMA. Almost always 5. This is only useful with a SoundBlaster 16 or higher.

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