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a bit of mistyping on my part... I don't know much about bit-slice processors. They seem like an interesting historical footnote at this point. Are there any

a bit of mistyping on my part... I don't know much about bit-slice processors. They seem like an interesting historical footnote at this point. Are there any current applications for the technology?

pkaye 9y ago
Bit-slice processor is where the hardware blocks are partitioned along bit boundaries. For example combine 4 chips of 4-bit wide data path to form a 16-bit processor. This was from when chips were not dense enough to fit a whole processor into one die.
- michrassena 9y ago
  After doing a tiny bit of reading, it seems in early minicomputer days bit-slice processors weren't an exotic technology at the time. I wonder why people didn't combine 16 chips to create 64-bit processors. Or did they?
  - kjs3 9y ago
    They did. The 64-bit floating point unit in many PDP-11s used 16 4-bit AM2901 bit-sliced processors. Also know that over time, 8-, 16- and 32-bit slices came along, so you didn't need as many chips to build wide-word machines.
  - Someone 9y ago
    Look at the years the CPUs mentioned in https://en.wikipedia.org/wiki/Bit_slicing https://en.wikipedia.org/wiki/Bit_slicing were produced. That was not a time where there was demand for 64 bit processors (not surprisingly. RAM cost around $6000 per Megabyte in 1980, according to http://jcmit.net/memoryprice.htm http://jcmit.net/memoryprice.htm, so you would have to pay around $24 million to run out of space on a 32-bit CPU) Of course, 64 bit registers and less memory would have been useful for scientific computations. However, I think it is hard to build a fast integer multiplier from bit-sliced CPUs (you can, but by the time you are done, the CPU doesn’t look like a cascade of smaller width CPUs anymore). I would guess making floating point perform on bit sliced processors has its challenges, too.
  - pkaye 9y ago
    Probably cost and performance. When you string more of these chips together, the propagation delay increases which means your clock speed must be inversely.
  - dboreham 9y ago
    They did. That was the whole point. Most designs were 32-bit but there was nothing to stop you going to 64-bit, floating point etc etc.

a bit of mistyping on my part... I don't know much about bit-slice processors. They seem like an interesting historical footnote at this point. Are there any current applications for the technology?

pkaye 9y ago

Bit-slice processor is where the hardware blocks are partitioned along bit boundaries. For example combine 4 chips of 4-bit wide data path to form a 16-bit processor. This was from when chips were not dense enough to fit a whole processor into one die.

michrassena 9y ago
After doing a tiny bit of reading, it seems in early minicomputer days bit-slice processors weren't an exotic technology at the time. I wonder why people didn't combine 16 chips to create 64-bit processors. Or did they?
- kjs3 9y ago
  They did. The 64-bit floating point unit in many PDP-11s used 16 4-bit AM2901 bit-sliced processors. Also know that over time, 8-, 16- and 32-bit slices came along, so you didn't need as many chips to build wide-word machines.
- Someone 9y ago
  Look at the years the CPUs mentioned in https://en.wikipedia.org/wiki/Bit_slicing https://en.wikipedia.org/wiki/Bit_slicing were produced. That was not a time where there was demand for 64 bit processors (not surprisingly. RAM cost around $6000 per Megabyte in 1980, according to http://jcmit.net/memoryprice.htm http://jcmit.net/memoryprice.htm, so you would have to pay around $24 million to run out of space on a 32-bit CPU) Of course, 64 bit registers and less memory would have been useful for scientific computations. However, I think it is hard to build a fast integer multiplier from bit-sliced CPUs (you can, but by the time you are done, the CPU doesn’t look like a cascade of smaller width CPUs anymore). I would guess making floating point perform on bit sliced processors has its challenges, too.
- pkaye 9y ago
  Probably cost and performance. When you string more of these chips together, the propagation delay increases which means your clock speed must be inversely.
- dboreham 9y ago
  They did. That was the whole point. Most designs were 32-bit but there was nothing to stop you going to 64-bit, floating point etc etc.