Intel 486SX

Intel 486SX

(processor)
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.

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).
References in periodicals archive ?
manufactures and markets, direct to end users, ISA (Industry Standard Architecture) and PCI personal computer systems and work stations based on the Intel 486SX, DX, and DX2, DX4 and Pentium microprocessors worldwide.
3 volt Intel 486SX processor running at 20 MHz, with an internal 120 Mb Hard Disk Drive.
Through support for x86 processors -- including the Intel(R) E3G, Intel 486SX SF, and the AMD Elan(TM) -- as well as its integrated PC Card support, the MobilePRO suite provides manufacturers with an important low-level system software solution for the industry's leading embedded operating systems.
manufacturers and markets, direct to end users, ISA and PCI personal computer systems and work stations based on the Intel 486SX, DX and DX2, DX4 and Pentium microprocessors worldwide.
manufactures and markets, direct to end users, ISA and PCI personal computer systems and work stations based on the Intel 486SX, SL, DX, DX2 and DX4 and Pentium microprocessors worldwide.
The HandBook SX-25 uses a 25MHz Intel 486SX processor and includes 4MB RAM and an 80MB hard drive.
Packed with the powerful Motorola 68LC040 and Intel 486SX microprocessor, the Macintosh Quadra 610 DOS COMPATIBLE is designed to provide users with more options than ever before, while allowing them to protect their software investment.
The system features a 25 MHz 68LC040, powering the Macintosh computer environment, and a 25 MHz Intel 486SX, which runs both DOS and Windows-based software.
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