With this card installed into one of the expansion slots on the main board it was possible to run software created under the CP/M-80 operating system. This card when fitted into the ACT Sirius 1 or Victor 9000 made use of the vast software library available to the CP/M-80 user.

CP/M (Control Program for Microcomputers) is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations, and were migrated to 16-bit processors.

Differences between CP/M-80 and CP/M-86 are such that programs created for CP/M-80 will not run under CP/M-86. Commands in CP/M-80 have file type "COM" while CP/M-86 commands have file type "CMD". However many source files such as Microsoft BASIC programs areinterchangable between the two systems. The amount of RAM under CP/M-80 is limited to 64K because like most 8-bit CPU's the Z80 is only designed to address 65536 bytes of memory. While thetwo operating systems are outwardly similar from a users perspective, there are major differences in the internal organisation that reflects the different architecture of the8080 and the 8086 CPU families.

Below are some images of the card including some close-ups of the main components on the card.

The card contains its own Z80 processor working at 4 MHz (?).
Zilog Z80 microprocessor is an 8-bit CPU object-code compatible with Intel 8080 CPU. The Z80 includes full set of 8080 registers and instructions, and supports 8080 interrupts. In addition to that, the Z80 has many enhancements:

• 80 new instructions, including block transfer, bit and string manipulation instructions.
• 2 new index registers and a duplicate set of general-purpose and status registers.
• New types of interrupts for Z80 and non-Z80 peripheral devices.
• Single +5V voltage.