TOCR 4.0 & 5.1 both have a 32-bit and 64-bit variant. The 64-bit version of TOCR 4.0 or 5.1 will only work with 64-bit versions of Windows. The 32-bit version is compatible with both 32-bit and 64-bit versions of Windows.

When you install TOCR 4.0 or 5.1 on a 64-bit machine, the 64-bit and 32-bit variants will both be installed. You cannot call both of these variants simultaneously unless you have installed at least two licences.