These computers are new versions of the PET series. The main improvement was the new ROM version (v4.0) which offered new possibilities such as direct disk operation commands (DLOAD, DSAVE, COPY, HEADER, etc.) or the ability to repeat cursor control characters by holding down keys. Late models also had a larger screen (12'') than the 2001 computers.
The disk drives were "Intelligent", which means that they were CPU driven (MOS 6502) and had internal RAM (4 KB) & ROM (16KB, which contained the DOS).
The 4032 and the 4016 were sold with an 80-column dot matrix printer (5x8 character matrix). This printer (4022) was an Epson printer with a Commodore name on it.
Dave Ridley reports:
CBM & PET 4000/8000 series - Brings back the memories! I used to fix these things, and boy did they have some classics. Regular problems were caused by the chip sockets going intermittant together with the molex power connectors burning out! Fix - remove chip squirt with RS Solvent Cleaner and stick them back. The external Disk units were connected by IEEE connectors. These disk drive units would fail, many a time I would open a unit up onsite(rather like opening the bonnet of a car) to find a pair of rectifier diodes that had got so hot they had actually melted themselves out of the board and fallen into the base.