Circuit diagram

The 25LS2538 chip is somewhat like a 74LS138, but also able to assert all eight outputs at once. No longer made or commonly available. The Elektor design replaced it with a fast 32-byte PROM (82S123). It could also be replaced with a PAL16L8 chip.

Original board:

2017 reproduction:

Has a phono video output socket and a modern crystal oscillator module.