The Inves Spectrum 48K+ (sold in Spain as the Inves Spectrum+) looks like a Sinclair ZX Spectrum+ from across a room, but Investronica built it on its own board, with its own ULA and its own ROM, and sold it from 1986 at 19,900 pesetas.
Why it matters
Investronica had been Sinclair’s Spanish importer. New Spanish tariffs had made local manufacture cheaper than importing, so in 1985 it showed a Spanish-made Spectrum 128 at SIMO in Madrid, and its own Spectrum+ followed in 1986, the year Amstrad bought Sinclair. The engineering is the interesting part. A Texas Instruments TAHC10 replaces the Ferranti ULA, two TMS4464 chips replace sixteen RAM chips, and a crystal at five times the CPU clock lets the ULA and Z80 share memory without the delays that Sinclair’s contended memory causes. That redesign is also why Commando, Bomb Jack, Arkanoid and Top Gun struggle on it. The dispute afterwards is murkier. English Wikipedia says Amstrad sued in 1987 and won a ruling in 1991, while Parcela Digital reports the Spanish Supreme Court finding for Investronica in September 1997. Those accounts cannot both be right. No sales figure turned up in any source consulted.
What to check before you buy
- Run several games, and include Commando, Bomb Jack, Arkanoid and Top Gun. They are known to misbehave on this machine, so poor results are normal; look for a crash or garbled screen on titles that others report working.
- Look at the badge. A genuine Inves has a black embossed inves logo at top left and Spectrum+ in red, with no Sinclair logo or rainbow. A plain Spectrum+ case with an Inves board swapped in, or the reverse, is possible.
- Press every key and look for dead groups. The Spectrum+ membrane is the commonest Spectrum fault, and a trapped membrane leg near the TV modulator causes the same symptoms.
- Check the Kempston joystick port and the reset button are intact, and ask whether the Spanish-labelled keyboard is original. The Spanish ROM messages show on a bare BASIC prompt.
- Ask about the power supply. It is a 9 V centre-negative unit and differs from the original Sinclair one, so confirm polarity and voltage before plugging in anything that is not the matching adaptor.
