Compupter Architecture Notes
Compupter Architecture Notes
Compilation of important things to know for your Comp Arch class
| Binary Spot | Digit |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 4 | 2 |
| 8 | 3 |
| 16 | 4 |
| 32 | 5 |
| 64 | 6 |
| 128 | 7 |
| 256 | 8 |
| 512 | 9 |
| 1024 | 10 |
| 2048 | 11 |
| 4096 | 12 |
| 8192 | 13 |
| 16384 | 14 |
| 32768 | 15 |
| 65536 | 16 |
| 131072 | 17 |
| 262144 | 18 |
| 524288 | 19 |
| 1048576 | 20 |
| 2097152 | 21 |
| 4194304 | 22 |
| 8388608 | 23 |
| 16777216 | 24 |
| 33554432 | 25 |
| 67108864 | 26 |
| 134217728 | 27 |
| 268435456 | 28 |
| 536870912 | 29 |
| 1073741824 | 30 |
| 2147483648 | 31 |
(from the Patterson Book) How the segments of memory are split up (note that this is generally accepted for the simulator, on actual MIPS chips the partitions could be set differently or non-existent)
Floating Point
usually given in hex, such as 0xBE4CCCCD Then, simply convert to binary, there is a shortcut for doing this… each digit/letter cooresponds to 4 binary bits (8 4 2 1)…
signed bit (1 bit) exp (8 bits) mantissa (23 bits)
sign of 1 is negative, 0 is positive exponent = convert as usual from binary to decimal, then you need to subtract 127 from your result (exp -127) mantissa = start from the left most bit in mantissa, then the result is that number * 2-1… and proceed to the next 2-2 * the next number, and move on till you hit the last 1. Because 0 * anything = 0, you can essentially skip the 0s, but make sure to still increment the exponent based on the position
Now that you got your mantissa, use this formula to convert it to decimal!
(-1)signedbit * (1+mantissa) * 2exp = end result!
Cache Formulas
| Block is composed of: Tag | Set | Offset |
tag + set = logbase2(# of blocks in cache)
Size of main address – set – offset = tag
(size of main memory)/(size of block) = # of blocks in cache
2offset = size of block
2set = # of rows
N is for the n in n-way set associative (2-way SA -> = 2) N*2set = # of blocks in cache
Total bits in cache = (size of block * 8 + 2 + tag) * N * 2set //in writeback
Total bits in cache = (size of block * 8 + 1 + tag) * N * 2set //in writethrough
Stack = LIFO
Queue = FIFO
Miss – no load to cache
- Go to direct main memory o Write into memory directly
WB = Write Back
WA = Write Allocate
WT = Write Through
LRU = Least Recently Used
No WA = No-write allocate (also called write-no-allocate or write around): data at the missed-write location is not loaded to cache, and is written directly to the backing store. In this approach, data is loaded into the cache on read misses only.
1 Bit = 8 Bytes
4 Bytes = 1 Word = 32 Bits = 1 Instruction
220 = megabyte
Stages
IF - fetch instruction
ID - decode instruction
EX - execute instruction
MEM - Read memory
WB - write back (only needed for LW and such commands)