the BOOT command, or the F9 key. The majority of disks shipped with SAMDOS, the system's first DOS, on them so that they could be directly booted. An improved replacement, MasterDOS, was also developed offering faster disk access, more files and support for the real-time clock accessory to provide file timestamps amongst many other improvements. The BASIC was very advanced and included code for sprite drawing and basic vector shapes such as lines and circles. The screen co-ordinate system for these was variable and could be arbitrarily scaled and centred. A provision for "recording" sequences of graphics commands so that they could later be repeated without the speed penalty of a BASIC interpreter in between was provided. The machine is capable of running CP/M 2.2 using the Pro-Dos software with support for both 720 Kilobyte format disks and IDE drives Disk drives The SAM originally used Citizen 3.5 inch slimline drives which slotted in below the keyboard to provide front-facing slots. Like IDE hard disks, these enclosures contained not just the drives but also the drive controllers, a WD1772-02, with the effect that the SAM could use both drives simultaneously. Due to a flaw in the Coupé's design, resetting the machine while a disk was left in a drive would be liable to cause data corruption on that disk, as while RESET is held in, no 8Mhz clock signal is sent to the drive's controllers. The double density disks used a format of 2 sides, 80 tracks per side and 10 sectors per track, with 512 bytes per sector. This gave a total capacity of 800 KB, though the standard directory occupied 20 KB leaving 780 KB free for user files. Files were stored in the same structure as MGT's original +D interface, but with additional codes used for SAM Coupé file types. The disk encoding (NRZ), encoding strategy (linear angular velocity), and track and sector header formats were compatible with those used on the IBM PC and Atari ST, and programs were available to read FAT formatted disks. Expansion ports A large array of expansion ports were provided, including: Two internal drive bays. Non-standard SCART connector offering composite video and digital and linear RGB as well as power input. 64-pin Euroconnector for general purpose hardware expansions. Mouse socket (proprietary format, although a converter for Atari ST style mice was later available). Light pen / Light gun and Stereo sound