Cyrix Cx486SLC

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Cyrix Cx486SLC / e
The one TI TX486SLC

The Cyrix Cx486SLC was the first full-fledged CPU from Cyrix , previously the company had sold math coprocessors that competed with the coprocessors from Intel.

The 486SLC was designed as an entry-level CPU to compete with Intel's i386 and i486SX . The company Texas Instruments , which made the chip for Cyrix, sold the Cx486SLC under its own name as 486SXLC. This CPU had an 8  KiB L1 cache instead of just 1 KiB. The similarly named chips from IBM ( IBM 486SLC ) were not related to the Cyrix design.

Technical

The CPU was introduced in May 1992 and - like the Cyrix 5x86 later, for example - was a hybrid CPU: It had the characteristics of a more modern processor design (in this case the 80486 ), but the chip housing had the pin assignment - the so-called pinout - of the previous generation, here that of the i386SX. The CPUs clocked at 25, 33 and 40  MHz , but instabilities were evident at 40 MHz on some operating systems.

The 486SLC can be described as an i386SX with a stripped-down 80486 instruction set and an additional 1 KiB L1 cache. The connection assignment and thus also the 16-bit data bus and the physical address space limited to 16 MiB have been taken over from the 80386SX. Like the i386SX and 80486SX, the 486SLC did not have a built-in math coprocessor, but - unlike the 80486SX - you could use the math coprocessors of the i386SX, such as the i387SX or a compatible math coprocessor. Due to the older and less powerful bus interface and the smaller L1 cache, the performance of the CPU was not comparable to the performance of the i486SX, but compared to the 80386SX there was a huge performance boost that encouraged many manufacturers to use their old 386SX mainboard designs to upgrade with this new CPU and to bring it to the market as a cheap offer under a 486 designation - a strategy that has often been denounced as a fraudulent label by users and the trade press.

The 486SLC was therefore primarily used in special offers or to upgrade older computers. Since it also consumed little power, it was also used in laptops , the technology of which - comparable to desktop computers with this CPU - often came from the i386SX era.

This processor is still in use in simple NAS systems such as the Amit MGB 111 (identical in construction to Fibrionic PE-4088 or Airlive 6500 FS).

Cx486SRx²

Since Cyrix came under pressure because of the falling prices of the i486 processors and the Cx486SLC was selling less and less, an improved version of the Cx486SLC was brought onto the market in September 1993 with the Cx486SRx² . This CPU ran internally similar to the i486DX2 with twice the clock frequency. Clock rates of up to 66 MHz were now possible. This CPU was therefore mostly used to upgrade older 80386 PCs.

Model data

Cx486SLC

Texas Instruments 486SXLC with 8 KiB cache.
Texas Instruments TX486SLC / E.
  • Code name:
  • Sold as: Cyrix Cx486SLC & Texas Instruments TX486SLC or 486SXLC.
  • L1 cache: 1  KiB , unified (8 KiB for the 486SXLC)
  • L2 cache: depending on the motherboard or chipset used
  • Socket for 80386 CPUs with a front side bus from 16 to 33 MHz
  • the Cx486SLC / e is a low-power version
  • the Cx486SLC / eV is a low-power and low-voltage version
  • Operating voltage (VCore):
    • Cx486SLC: 5V
    • Cx486SLC / e: 5V
    • Cx486SLC / eV: 3.3V
  • Release DATE: 1992
  • Manufacturing technology: 0.8 µm, CMOS
  • The size: 108 mm² with 0.6 million transistors
  • Clock rates: 20, 25, 33 and 40 MHz

Cx486SRx²

  • Code name:
  • Sold as: Cyrix Cx486SRx²
  • Release DATE: September 1993
  • L1 cache: 1  KiB (unified)
  • L2 cache: depending on the mainboard or chipset used
  • Upgrade for 80286 , 80386SX and Cx486SLC CPUs with a front side bus of 16, 20 and 25 MHz
  • Operating voltage (VCore): 3.3V
  • Operating voltage (I / O): 5 V.
  • Manufacturing engineering: ?
  • The size:? mm² with 0.6 million transistors
  • Housing: PQFP -100
  • Clock rates: 33, 40 and 50 MHz

See also