Located in slot 5 of the Basic Operator Station chassis, the EDAC/Memory Controller Card provides memory control and error detection and correction functions. When astation uses 1 Meg memory board 82117038-001, the EDAC function is provided by the 82117038-001, and this card is not used.

The EDAC refreshes memory values by continuously rewriting values to the CMOS memory of the station.

This card can detect and correct single bit errors. Multiple bit memory errors cannot be corrected by this card, and will cause the station to reset.

The ECAC card also maps memory addresses above 32K. The processor has only 16 addres lines, limiting direct addressing to 32K. EDAC mapping allows memory access up to 640K.

Timing is provided by the EDAC card for the CPU and all DMA devices.

The EDAC board has 1 LED which indicates a memory error when lit.

Jumper:

B o A-C Normal – Mapping enabled A o–o C A-B Unused – Mapping disabled