| ??? 11/28/08 17:56 Read: times |
#160381 - Quick PC history Responding to: ???'s previous message |
Recall, that the original PC had 8-bit wide data bus, and only a few claimed that 640kB would be too much... ;-) A quick note about the 640kB of the original PC. The first model of the IBM PC actually only had 16kB RAM, and three empty memory banks to allow an update to a whopping 64kB. The second version got souped up and supplyed with one 64kB memory bank and support for upgrading to 256kB with all four banks filled. Neither of the first two models where even close to reaching the 640kB address space pre-allocated for program memory, and for a long time there where no vendor who could produce dense enough expansion boards to allow such a memory expansion to fit in the available expansion slots. A whole world blamed the PC designers for putting a hard limit at a measly 640kB, instead of realizing that the designers put the limit at 10 times the amount of memory a fully stocked motherboard of a very, very expensive machine could support. The above gives a bit of perspective to "much RAM". A modern optical drive has enough high-speed RAM that the supercomputer guys of 1981 would have drooled and been ready to kill... There was a reason why Intel did not saw a need for more/better 8051 instructions to access "large" blocks of RAM. |
