3 ms·

I saw some projects in the 70s where they add a math co-processor to a standard 8-bit CPU by interfacing to an off the shelf calculator chip, with all the same

I saw some projects in the 70s where they add a math co-processor to a standard 8-bit CPU by interfacing to an off the shelf calculator chip, with all the same issues. I'm sure it would be slower, but maybe the physical size might be the same as the ROM chips (1702s?) that would be required for the floating point code.

duskwuff 6y ago
Back in the 90s, Intel ran a print advertisement for the Intel 387 portraying their competitors' math coprocessors as pocket calculators: https://i.pinimg.com/originals/fd/1d/01/fd1d012149d9e7d67371747a91f69b21.jpg https://i.pinimg.com/originals/fd/1d/01/fd1d012149d9e7d67371... I guess there was something to that? :)
- kens 6y ago
  That's an interesting ad, but a bit ironic given Intel's later Pentium floating point division bug. On the topic of using calculator chips as coprocessors, National Semiconductor introduced the MM57109 Number Cruncher Unit (that is the real name) in 1977. It was essentially a repackaged 12-digit scientific calculator chip, operating on binary-coded decimal values with values entered in Reverse Polish Notation. This chip was absurdly slow; a tangent, for instance, could take over a second. http://www.projects.scorchingbay.nz/dokuwiki/_media/electronic/datasheet/national/an-186_mm57109_interface_to_microprocessor.pdf http://www.projects.scorchingbay.nz/dokuwiki/_media/electron...