I doubt that there is a one to one correspondence between the command sets - let alone the driver. Maybe you can get someone from Agilent to confirm this if you can get them to help with an obsolete instrument. You might have to compare the instrument manuals yourself to see the differences. If you were familiar enough with the old instrument, it's commands, LabVIEW, and the driver for the 4192, in theory you could re-write the 4284 driver and rename the functions to match the old functions. That of course might be a bit confusing since you would then be calling, for example, HP 4192A Measure.vi that is actually a 4284 measure VI. This is the sort of situation that IVI would fix if there was an actual IVI class for your instrument. Unfortunately, there's not and you're going to have a bit of work ahead of you.