Memory Data Register (MDR) / Memory Buffer Register (MDR) Acts like a buffer and holds anything that is copied from the memory ready for the processor to use it.
{"Image DocumentName": "Memory Address Register (MAR)", "Image ImageDescription": "Also used to hold / store the memory address (copied from the PC) that contains the instruction to be used next but can also hold the memory address of data needed to execute the next instruction. After the address has been copied from the PC into the MAR the PC is incremented by 1. Assumes that the instructions are in consecutive locations but if it is a jump instruction the PC will be altered again at the end of the cycle.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}