Afraid I'm unable to help, but can someone tell me if Smiths ever incorporated VNAV into their FMS for the A310?
My airline, BCAL, had two A310-200s from 1984-86 (they ended up in Tripoli...). Our Smiths FMS was in the minority on A310s, most airlines having Sperry. It was a very good piece of kit for its day, but in 1986 its VNAV mode was still being developed, whereas the Sperry FMS already had it, IIRC. I think Smiths's lack of resources clinched Airbus's decision to offer only the Sperry-Honeywell FMGS on the A320.