: NI provides its own implementation. For version 5.12 specifically, you may need to check the NI Driver Download Archive for legacy compatibility with older operating systems like Windows 7 or older LabVIEW versions.
No. Version 5.12 was exclusively 32-bit. For 64-bit, you need Visa COM 6.x or newer. visa com 5.12 type library download
Companies like , TSYS , or Fiserv can provide the library as part of a legacy support contract. : NI provides its own implementation