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The CM-2 also had hardware floating-point units (off-the-shelf chips from Weitek, paired with groups of 32 bit-serial processors, via custom chips with "transpo
by rst 4y ago
The CM-2 also had hardware floating-point units (off-the-shelf chips from Weitek, paired with groups of 32 bit-serial processors, via custom chips with "transposers", which would transpose 32-bit floats read bit-serially out of 32 bit-processors memories, into 32-bit floats presented in parallel to the FPU chips).
- chris_st 4y agoAka "Slice-wise" mode. The FP units were optional (the project I was on didn't need FP, so we didn't have them). IIRC slice-wise mode was only available via their parallel FORTRAN compiler.
- rst 4y agoThe distinction was slightly more subtle -- "slice-wise" was a storage mode for data in which a 32-bit float would be stored as one bit in the memory of 32 processors, so the "transposers" could be bypassed going in and out. It was supported by the Fortran compiler and by a microcode-like internal layer called "CMIS" (which was, I think, available to at least some customers -- I worked there). Code in other languages still used the FPUs, if available -- but they paid the "transpose in, transpose out" overhead on every operation.
- chris_st 4y agoThanks for the clarification -- interesting to know!