Word sizes

by IanB on April 16, 2012

System: Windows 7 64-bit

Q: This is a general question pertaining to any PC. I often use registry tweaks as suggested in your wonderful magazine. My new laptop is running 64 bit Windows 7. Often your advice to make a tweak involves creating a new Dword and I’ve never questioned this before. But I was applying some of the printer and network tweaks from the Registry Workshop in issue 137 and I noticed it asks me if I wish to create a new Dword (32-bit) or Qword (64-bit).

So if I’m employing a registry modification, should I be making a Qword if running a 64-bit OS instead of a Dword? If so, should you be alerting readers to this? Or am I barking up the wrong tree and it has nothing to do with 32-bit versus 64-bit?

A: Whether you use a Dword or a Qword is dependent on the length of the entry rather than the version of Windows. Dwords came first, but Qwords were first introduced in Windows 2000 and you can use them on 32-bit systems.

To explain how and why this works we need a bit of history. The universal unit of digital information is the byte, consisting of 8 bits (binary digits), each byte forming an individual text character. The x86 platform, which still forms the basis of modern processor architecture, handled data in 16-bit (2 byte) chunks and this unit became known as a word. More recent systems use 32-bit or 64-bit words, but in order not to confuse things 32-bits is known as a double word (or Dword) and 64-bits as a quadruple word (or Qword). But effectively a Qword is still four 16-bit words bundled together rather than a single 64-bit one, so it’s just a way of getting more information into a field.

You only need to use a Qword in the registry when the particular program you’re dealing with requires it.


Qwords in the registry aren’t unique to 64-bit systems

Originally featured in PCU 139


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