The memory size can be either 32K or 64K bytes as standard, expandable to 512 K bytes. There is a separate 16K byte dedicated video memory. A 24K byte ROM contains MTX-BASIC, the system monitor, supplementary languages and utilities. The standard interfaces included are tape cassette (Read/Write to 2400 baud), keyboard, cartridge port, twin joysticks, parallel centronics type printer port, uncommitted parallel input/output port, colour TV output with sound, composite video output - monochrome or colour, and audio output. Optional interfaces include a completely independent twin RS232C with buffered bus extension, Colour 80 Column Board, Floppy Disc System, Silicon disc fast access RAM boards, and a Winchester Disc System. The keyboard consists of 79 full travel typewriter style keys mounted on a steel base plate which is fitted to the Aluminium enclosure. Aluminium was chosen for good heat dissipation, durability and RFI shielding.