The amount of cache on the processor greatly affects the cost, why is this? is it because its harder to make due to the small size of the chip? and therefore more expensive than other memory?
2006-09-04 12:50:47 · 5 answers · asked by litleshortarse 1 in Computers & Internet ➔ Hardware ➔ Other - Hardware
The short answer is number of transistors.
For every new chip the designers have what's referred to as a transistor budget. The process size (e.g. .9 um) defines how tightly transistors can be packed onto a piece of silicon. As all silicon wafers have defects on them, and hitting a defect on a chip effectively destroys that chip, the bigger it gets, the more likely a given chip on a wafer is to be broken.
Thus the bigger the chip, the lower your yield. To make a profit the chip therefore needs to be as small as possible. Hence a budget for transistors.
Now... For a given number of transistors the designer must then decide how many to use for logic, how many for registers etc and hot many for cache. It's a balancing act. More cache means fewer registers & less logic.
So.
More cache == probably slower chip internally (Because you have less logic & probably need to do things in more steps to accomplish the smae task).
More cache == bigger chip size. So number of chips on a wafer goes down. (Revenue goes down because a wafter costs almost the same to process if it has 2 or 200 chips on it).
Bigger size == lower yield. If the wafer has 1 defect on it, and you get two chips, your yield is going to be 50%. If you have 200 chips, one will be broken because of defects, so your yield is 99.5%).
2006-09-06 20:09:27 · answer #1 · answered by Hamish M 2 · 1⤊ 0⤋
Because the cache memory is of Static Memory type unlike the RAM which is of Dynamic Memory type. Because it is faster than RAM , it is generally very expensive to make.
2006-09-04 14:24:01 · answer #2 · answered by Mouktik Sarkar 2 · 0⤊ 0⤋
It is more difficult to manufacture a large silicon based chip to house the memory registers, this may change with new manufacturing processes but it will take years to filter through to us
2006-09-05 02:09:43 · answer #3 · answered by jarrajackie 3 · 0⤊ 0⤋
You've answered you own question!!!
Also cache memory is much faster than standard RAM and therefore more expensive to manufacture.
2006-09-04 12:59:22 · answer #4 · answered by Ian B 2 · 0⤊ 0⤋
Simply put, memory takes up a heck of a lot of real estate.
In the space it takes to store just 3 bytes of data you can put an accumulating register.
2006-09-04 12:58:07 · answer #5 · answered by a tao 4 · 0⤊ 0⤋