6. A system has a main memory with a cache plus a disk for virtual memory. The cache access time is 20nsec and the hit ratio for the cache is 90%. If the data being referenced is not in the cache, then it must first be loaded to the cache and then read from the cache into the processor. The load from main memory to the cache takes 60 nsec. If the data is not in main memory then it must first be fetched from the disk which takes 12 msec followed by 60 nsec to copy it to the cache from main memory. If the main memory hit ratio is just 60% what is the average access time for this system? Show all work. 7. A computer system has a main memory and an instruction cache. The main memory access time is 120nsec and the cache access time is)30nsec A) what is the hit ratio if the effective access time is 60nsec, Show your work. B) In the system in part A if the hit ratio gets to 90% what is the effective access time? 8. Consider a direct mapped cache system in which the main memory address is laid out as shown in Figure 4.10 on p. 136. If the word size is 1 byte, the block size is 16 bytes, the cache size is 64 K, and the main memory is 1 MByte, what is the corresponding tag, cache line, and word offset for main memory address 01234H? 9. Consider a 32-bit computer which has a 32-bit address and a 32-bit instruction size composed of two fields: the first 7-bits contains the opcode and the remainder the immediate operand or an operand address. A) What is the maximum directly addressable data memory capacity (in bytes)? B) For instructions which use the immediate addressing mode what is the range of integers that can be loaded into a register C) How many different instructions are possible with this arrangement