Could Nintendo be the oldest company currently involved with tech?
Nintendo was founded in 1889.
As just one counter-example; I'm sure there are plenty more/earlier: Siemens was founded in 1847 (edit: by building telegraph equipment and infrastructure).
Edit: I'm sure there must have been earlier companies involved in "tech" that are still relevant? Maybe let's think about "tech" as "information technology" companies?
On the other hand, Western Union is still trading under its original name.
Kiewit formed in 1884.