What is reason for the power density going down between '80 and '90, even though the no. of transistors kept increasing?
DOH
I'm not sure, but I know that it's not the same as the number of transistors--it's the amount of power consumed per unit area, so if the area increased then the power density would decrease. If the number of transistors increased, but they became more efficient, or were spread out over a larger area, then that may explain the power density changes. Not sure though... Tried Googling without luck :(
krishang
I think your argument makes sense, i.e. the area did increase. I just noticed that, while 8086 chips were packaged as Dual Inline Package (DIP), the 386 chips were packaged as 132 pin PGAs. That seems like a reasonable increase in size, but may be we're missing a bigger factor here?
hrw
I think the alternative way to increase # transistors, other than increasing the density, is to increase the space of the chip. In this way, the power density doesn't increase while total computation power goes up. Why does this solution not work?
haoran
There are at least two reasons we don't want large chips:
1. we don't want chips taking too much space in our device. For example, most of the space in my iPad is taken by battery. A larger chip will result in smaller battery if we have fixed amount of space.
2. Larger chip will have lower yield rate. The cost will go up.
What is reason for the power density going down between '80 and '90, even though the no. of transistors kept increasing?
I'm not sure, but I know that it's not the same as the number of transistors--it's the amount of power consumed per unit area, so if the area increased then the power density would decrease. If the number of transistors increased, but they became more efficient, or were spread out over a larger area, then that may explain the power density changes. Not sure though... Tried Googling without luck :(
I think your argument makes sense, i.e. the area did increase. I just noticed that, while 8086 chips were packaged as Dual Inline Package (DIP), the 386 chips were packaged as 132 pin PGAs. That seems like a reasonable increase in size, but may be we're missing a bigger factor here?
I think the alternative way to increase # transistors, other than increasing the density, is to increase the space of the chip. In this way, the power density doesn't increase while total computation power goes up. Why does this solution not work?
There are at least two reasons we don't want large chips: 1. we don't want chips taking too much space in our device. For example, most of the space in my iPad is taken by battery. A larger chip will result in smaller battery if we have fixed amount of space. 2. Larger chip will have lower yield rate. The cost will go up.