Nicolet DSO

(Dwight:) I opened up the Nicolet 2090-III DSO at the radio museum last week. There were no 9900 micro-procs (no I/O options I guess), I am somewhat surprised the basic scope seems to be done with dedicated logic. Three 2901 bit-slices, two Analog Devices ADC-80's (IIRC) for the A-D, bank of 2141's (nic) for RAM, some ROM's I think, and a lot of SSI/MSI. Date codes early 80's. The electronics may be interesting for the period, but as with other Nicolet equipment I have seen, the physical design is horrible in regards to accessibility and maintenance. Major portions of logic are buried and inaccessible without tortured dismantling. Fired it up, seems to work for capturing sine wave from finger on input. Still have to figure out some of the functions. I take it the 1H, 2H, 1Q, 2Q, etc. modes are for recording in interleaved halves or quarters of memory? Do you know if the SUB function subtracts a new sweep from the currently active memory, or does it operate on two portions of already-recorded memory?