It was based on and designed to have a compatibility mode with the ZX Spectrum 48K with influences from the Loki project[1] and marketed as a logical upgrade from the Spectrum with increased memory, graphical and sound capabilities, native peripheral support (floppy disk, MIDI, joystick, light pen/light gun and a proprietary mouse).

[6] The capitalised SAM is an acronym for 'Some Amazing Micro' according to Alan Miles in an interview with ZAT magazine.

This was originally prototyped using wire-wrapped 7400-series logic chips, before being produced as a VLSI VGT-200 gate array ASIC.

The computer has a direct connection for a cassette recorder for data storage but two 3.5 inch floppy disk drives can be installed within the case as well or externally using an interface.

[15][11] The non-standard SCART display connector includes both composite and RGB output, as well as signals to drive a 16-colour TTL monitor.

Hardware sprites and scrolling would have greatly improved the performance of games, unfortunately there was insufficient wafer space on the VLSI ASIC to include such circuitry.

In modes 3 and 4 the display could be disabled completely, eliminating these memory contention delays for a full 6 MHz running speed.

Font size can be altered to make text display in 32, 64, or 85 columns, and double height characters are also possible.

If this is undesirable, then systems variable (SVAR) 1 can be set to a 2-character value for the new lower and upper case cursor characters to be used.

The ROMs contained only the bootstrap code and the DOS was instead loaded from disk using the BOOT command, or the F9 key.

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.

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 the RESET line is held logic low the ASIC (that generates the 8 Mhz clock) is halted thus no clock signal is sent to the drive's controllers.

This made signal interference from the AC/DC converter common and it was a popular but entirely unofficial modification to remove the modulator and keep it as a separate unit.

In order to match the processing speed of the ZX Spectrum (3.5 MHz), the SAM Coupé introduces extra wait states in display Mode 1 (the ZX Spectrum-compatible graphics mode) to slow down the CPU to roughly match the rate of that system.

It was possible to convert some games and demos by directly hacking the 128K code or by using a software patcher with the 1 megabyte RAM expansion to provide the address space.

Due to unsuitable onboard break (NMI) buttons (needed to activate the Messenger software), a de-bounced break-button card was also provided, which plugged into the Coupé's expansion slot.