Dynamic RAM for SC/MP - refreshing for SC/MP systems

The dynamic RAM card in the April 1982 issue of Elektor has found many friends among Junior Computer owners. However SC/MP owners will also be pleased to discover that the same RAM card can be used by them. As a reward to all the SC/MP owners (for staying with us for so long), here are the modifications required to adapt the dynamic RAM card to their systems. 16K in 8 ICs on a single card is worth quite a lot, and SC/MP users should find whole new possibilities for their systems. Unfortunately the basic version was not suitable for the SC/MP system. This is due to the fact that the SC/MP system would interrupt the refresh instructions resulting in data being lost. The simple interface consists of a single IC, two resistors and two capacitors. Furthermore a set of wire links and connections (as shown in the table) must also be made. The circuit consists of a retriggerable monoflop MMV1, with a pulse length of approximately 10 us. As long as the NADS pulses keep on coming, the D. Pa...