With the arrival of the Spectrum 48K revision ISSUE 5, a new chip appeared that performed functions that in previous ISSUES were performed by the 74LSxx chip. This new chip is present in the 48K ISSUE 5 and 6, the Spectrum + 128K and the Spectrum +2 gray (renamed AMSTRAD 40058).

    This chip is impossible to get today and if it breaks, it was not possible to fix the Spectrum.