Hi Roger,
Thanks for your reply.
The label of my back shell only says...HW Version 4.2, SN: SN:H$-xxx71290. I do not see nay mention of MS or SI. bought my unit from R&L Electronics in Sep '20. Could it be it does not contain any of these chips?
My first instinct was to try which H4 dsu file would load on it, but am concerned I might brick this very useful instrument...
