[volt-nuts] Transmille 8081

[Alan Ambrose]

Ah also,

I forgot - this is also v interesting:

>>>

If, [for some reason], you think you need an 8.5-digit DMM, the 3458A is *still* king of INL, after all of these years.  The reason?  It's analog ASIC.  Matched JFET switches to ultra-high ratio stability highly interdigitated resistors.  This, and balancing JFET switch transitions during an ADC cycle is the "secret sauce" that is at the heart of the 3458A's stellar INL spec.  No one else has that.  No one else ever will. *WAY* too expensive for even Keysight to redesign these days.  Just is not going to happen...
<<<

Could you say a bit more about this? Did the 3458A not make economic sense for HP at the time? Is nobody buying 8.5s these days? The reason I ask is that I think we all have the general sense that as technology advances, getting to any particular  design objective gets slowing easier as the years roll on. This would be an interesting data point to illustrate why that isn't always so. Possible to say more?

Alan