Registers on Bus Differences from Von Neumann

The 'registers on bus' computer architecture is only slightly different than the Von Neumann architecture in that the design for a computer using the registers on bus architecture is almost identical to the design for a computer using the Von Neumann architecture. They are also programmed almost identically.

A computer using the registers on bus architecture uses the same parts as a Von Neumann computer architecture connected together in a slightly different way.

Next, we will consider a simple registers on bus computer. It will be almost identical to the Von Neumann computer described previousely and will be programmed identically. That is, it will run the exact same machine code with the exact same results.

The biggest part of the Von Neumann computer described in the book is memory. In fact, for a 32-bit version, there are about 4 billion latches in the memory and only 8 registers in the processor. The memory, including input and output 'latches,' is exactly the same in the Von Neumann and registers on bus architecture versions of this simple computer. That is, both designs use the exact same memory circuit.

The clock is almost identical. It is identical except that it generates a different timing pattern.

The logic unit is also identical. It does a rotate and mask operation and uses the exact same circuit.

The big DIFFERENCE between the simple Von Neumann computer and its registers on bus version is that all the registers are in one big latch in the registers on bus version. That is, instead of eight 32-bit registers, there is one 256-bit register made out of eight 32-bit registers arranged side by side. 256 is 32 times 8.

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