GEC 4082

The 4082 is a 4080 with 2 extra store address lines, so it can support 1Mb of core store. However, the BMC was still limited to accessing only the bottom 256kb of store. This was not a serious problem except for overlays (virtual memory swapping to disc), and for this, a second I/O processor was added which could access all of store but could only drive a single disc controller; this was known as an EDC, External Disc Channel.