Programming Method for Verifying an External RAM With Minimum Code
Original Publication Date: 1985-May-01
Included in the Prior Art Database: 2005-Feb-18
The address lines and the internal bits of an external RAM (random-access memory) are verified with minimum code. As shown in the flow chart, an address pointer is sequentially set to each byte of a RAM. Hex AA is written into the byte of the RAM to which the address pointer is set. After writing into the RAM address, the RAM address is read. If the RAM read what has been written into it, the address pointer is incremented to the next byte of the RAM. This is continued until Hex AA has been written and read from every address in the RAM. If any address does not read correctly, an error routine is entered; this produces an error signal, such as turning on a flashing light, for example. If all the addresses in the RAM checked satisfactorily, the address pointer is set to the second byte in the RAM.