Differences between HP scanners

Hello!

What are the differences between these scanners from Hewlett Packard:

- Scanjet 3c
- Scanjet 4c
- Scanjet 6100C

All have 600 dpi optical resolution, all have internal 30 bit and
external 24 bit color resolution.
When I scan a IT8.7 test chart on 3c and 4c the result is similar,
there are a few differences, but they are pretty small (the 6100C I
haven't tested up to now).



CU Peter