The Z2 system was an evolution of the Z1 model. Major change was a new CPU board using a 4 Mhz. Z80 microprocessor. The system, always based on the S-100 bus, proposed 21 connectors for S-100 cards and a stronger power supply able to supply additional peripherals. The front panel didn't offer any switches or control leds. 8080 based software made with the Z-1 model could run on the Z-2 system
The Z2-D (September 1977) version included 64 KB of RAM, one or two 92 KB (then 184 KB) formatted floppy drives and controller card.
The Z2-H system appeared in July, 1980. Using the Z-2 basis but including a 11 MB hard disk, two dual sided floppy disc drives and 64 KB of RAM memory.