Re:The Burroughs B5000 - 20 Years Later and Still Ahead of t...
by wglb on Tuesday May 22, 2012 @09:50PM
(#4011091)
Couple of interesting things that the article did not describe. The addresses of instructions in the b5500 were decimal. Yes, decimal.
IBM came out with the IBM 380 model 67 in about 1967 with it's first implementation of virtual memory. I believe that was done in conjunction with U. Mich.
In the 60s there was lots of discussion about virtual memory, what size should the "working set" be, and so on. As for many things in that time and actually decades later, ideas were not accepted until IBM implemented them. Many folk at the time thought that IBM invented virtual memory.
What is missing from most of these discussions is an even more remarkable machine (in my view), the Burroughs B1700. It did not have a fixed instruction set size--each program had a definition in the header of the file that specified the size of the word, the number of bits in the instruction field, and so on. In fact, the instruction codes were not fixed, and changed several times. Only the compiler writer and the firmware engineer had to agree on the meaning of the codes.
And yes, I believe that Alan Kay is right about misguided hardware architectures after all these years. There was lots of disappointment when the 360 instruction set came out when it was compared to the instruction sets that came before it. The instruction set of the DEC-10 and relatives was a thing of beauty. The PDP-11 was also quite nice, and if you have ever looked at a Motorola 6809, you can see some resemblance.
The Intel instruction sets continued this negative trend. It has always seemed to me that the instructions were designed with an eye to optimizing the wrong thing, and prematurely.
What Intel is good at are 1) design wins and 2) fab process improvements. Instruction set or software design, not so much.
We need somebody to turn this cart over and straighten up this mess.
IBM came out with the IBM 380 model 67 in about 1967 with it's first implementation of virtual memory. I believe that was done in conjunction with U. Mich.
In the 60s there was lots of discussion about virtual memory, what size should the "working set" be, and so on. As for many things in that time and actually decades later, ideas were not accepted until IBM implemented them. Many folk at the time thought that IBM invented virtual memory.
What is missing from most of these discussions is an even more remarkable machine (in my view), the Burroughs B1700. It did not have a fixed instruction set size--each program had a definition in the header of the file that specified the size of the word, the number of bits in the instruction field, and so on. In fact, the instruction codes were not fixed, and changed several times. Only the compiler writer and the firmware engineer had to agree on the meaning of the codes.
And yes, I believe that Alan Kay is right about misguided hardware architectures after all these years. There was lots of disappointment when the 360 instruction set came out when it was compared to the instruction sets that came before it. The instruction set of the DEC-10 and relatives was a thing of beauty. The PDP-11 was also quite nice, and if you have ever looked at a Motorola 6809, you can see some resemblance.
The Intel instruction sets continued this negative trend. It has always seemed to me that the instructions were designed with an eye to optimizing the wrong thing, and prematurely.
What Intel is good at are 1) design wins and 2) fab process improvements. Instruction set or software design, not so much.
We need somebody to turn this cart over and straighten up this mess.