Dynamic Memory Fault Replacement
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Many personal computers and workstation terminals, with or without display devices, have a requirement for a memory subsystem including large high density RAM (random-access memory). The latter has a higher failure rate than the supporting logic circuitry, and a cost problem arises in that service engineers (CEs) are called out unnecessarily frequently. Most of the faults are disclosed when the machine is first switched on by Basic Assurance Test (BAT) code which has the ability to check all memory modules. Error correcting codes could be used but suffer the disadvantage of high cost of implementation. In a first solution (Fig. 1) to the problem, the RAM memory 1 comprises a plurality of memory modules 2, each of which is one-bit wide. There are D data bit modules, one parity bit module and R replacement bit modules.