An Intel 486DX microprocessor with its floating-point unit disconnected. All 486SX chips were fabricated with FPUs. If testing showed that the CPU was OK but the FPU was defective, the FPU’s power and bus connections were destroyed with a laser and the chip was sold cheaper as an SX, if the FPU worked it was sold as a DX.
[Was this true of all 486SX chips?]
Some systems, e.g. Aopen 486SX, allowed a DX to be plugged into an expansion socket. A board jumper would disable the SX which was hard to remove because it was surface mounted.
Some SX chips only had a 16-bit wide external data bus. The DX has a pin to select the data bus width (16 or 32). On the smaller SX, that line is hard-wired to 16 inside the package. This is similar to the 286 SX, which was a 16-bit processor with an 8-bit external data bus.
The Jargon File claimed that the SX was deliberately disabled crippleware. The German computer magazine, “c’t”, made this same theory the basis of an April Fools Joke. They claimed that if one drilled a hole of a specified diameter through the right point on a SX chip, this would brake the circuit that disables the FPU. Some people actually tried (and then bought themselves new processors).
- Intel 487sx
processor A version of the Intel 486DX microprocessor with an extra pin, for use in the coprocessor socket of an Intel 486SX system. The 487SX provides the FPU which is missing in the 486SX. Although the 486SX is completely disabled when you install a 487SX, the 487SX design requires that you leave the 486SX in […]
- Intel 8008
processor A microprocessor intended for use as a terminal controller, and similar to the Intel 4040. The 8008 had a 14-bit PC and addressing and an eight level internal stack. It was followed by the Intel 8080. [Date?] (1994-10-31)
- Intel 80186
processor A microprocessor developed by Intel circa 1982. The 80186 was an improvement on the Intel 8086 and Intel 8088. As with the 8086, it had a 16-bit external bus and was also available as the Intel 80188, with an 8-bit external data bus. The initial clock rate of the 80186 and 80188 was 6 […]
- Intel 80188
processor A version of the Intel 80186 with an 8 bit external data bus (instead of 16 bit). This makes it cheaper to connect to peripherals. (1995-01-13)