JPS59114654A - Memory device - Google Patents

Abstract

PURPOSE:To reduce as less as possible the overheads due to the error checking and to improve the cost performance by changing the partial writing or reading method in response to the memory areas. CONSTITUTION:When a partial writing request is delivered to a momory 2 from a processor 1, an address deciding circuit 8 decides whether the designated address is within a specific memory area and then turns on a signal line 23 if the address is within the specific memory area. In a partial writing mode to the specific memory area, an error correcting circuit 14 produces and delivers an error correction code. A main control part 9 decides as a partial writing request to the areas excluding the specific memory area if the line 23 is not turned on. Thus the partial writing data added with bits only is delivered from the circuit 14. The partial writing is carried out to the areas excepting the specific memory area without taking reading operation of data.