The Spectrum 128 (code named Derby) is the successor of the Spectrum +. It was made just before Amstrad bought the right to use the Sinclair name in computer products. So it can be regarded as the last "real Sinclair Spectrum".
The 128 is the first real evolution of the old Spectrum. It has a lot of new features: 128kb RAM, a new sound chip (Yamaha AY-3-8912), RS232/Midi and video RGB outputs.
The Spectrum displays a menu when it is switched on:
- "Tape Loader" to run programs on tape,
- "Calculator" to enter operations without typing PRINT before,
- "Tape Tester" to test the input level of the tape recorder,
- "BASIC 48" and "BASIC 128".
The Spectrum 128 can use two versions of BASIC: BASIC 48 is just for the compatibility with the previous models and can't use the new features.
The Basic 128 mode has a full screen editor and the user can enter the Basic statements letter by letter instead of pressing key combinations. It has new keywords to use the extended memory as a RAM disk (unless bank-switching routines are utilized) and to handle the new sound chip and the MIDI out socket.
Because there were still large unsold stocks of Spectrum+ in the UK, the Spectrum 128 was first launched in Spain where the Speccy was already very popular. It was sold there with an external numeric keypad to connect the main unit. This "spanish model" doesn't boot on a "start menu" as the UK version does (thus spanish 128k models are slightly different than later UK models). But even after being introduced in UK it had a short market life and was replaced with the Spectrum +2.