Intel's existing low-end product - the venerable Pentium MMX - was no longer performance competitive. Moreover, its industry standard Socket 7 platform hosted a market of competitor processors which could be drop-in replacements for the Intel CPU. Intel therefore decided to forego the low risk strategy of producing a faster Pentium MMX and opt instead for developing a budget part that was pin-compatible with their high-end Pentium II product, using the Pentium II's Slot 1 interface.



Based around the same P6 microarchitecture as the Pentium II, and using the same 0.25-micron fab process, the original Celerons offered a complete package of the latest technologies, including support for AGP graphics, ATA-33 hard disk drives, SDRAM and ACPI. They worked with any Intel Pentium II chipset that supported a 66MHz system bus - including the 440LX, 440BX and the new 440EX - the latter being specifically designed for the "Basic PC" market.

Covington

The first Celerons (codenamed Covington) were essentially a Pentium IIs manufactured without any Level 2 cache at all. Although clocked at 266 or 300MHz - substantially higher than the old Pentium MMX - the cacheless Celerons were a good deal slower than the parts they were designed to replace.

Unlike the Pentium II with its Single Edge Cartridge (SEC) packaging, the initial Celerons had no protective plastic sheath around its processor card, which Intel called the Single Edge Processor Package (SEPP). This was compatible with Slot 1, allowing existing motherboards to be used, but the retention mechanism for the CPU card had to be adapted to handle the SEPP form factor.

Single Edge Processor Package

The early Celerons met with a less-than-enthusiastic market response, carrying little or no advantage over clone-based Socket 7 systems and failing to deliver any noticeable performance advantage. It was therefore no surprise when, in August 1998, Intel beefed up its Celeron range with the processor family formerly codenamed "Mendocino".

Mendocino

Starting with the 300A, all Celerons have come equipped with 128KB of on-die Level 2 cache running at full CPU speed and communicating externally via a 66MHz bus, making them far more capable than their sluggish predecessors.

Somewhat confusingly, all Celeron processors from the 300A up until the 466MHz were available in two versions - the SEPP form factor or in a plastic pin grid array (PPGA) form factor. The former was regarded as the mainstream version - compatible with Intel's existing Slot 1 architecture - while the latter was a proprietary Pin 370 socket, neither Socket 7 nor Slot 1.

Plastic Pin Grid Array

The use of a socket, rather than a slot, gave more flexibility to motherboard designers as a socket has a smaller footprint as well as better heat dissipation characteristics. Consequently, it provided OEMs with more potential to lower system design costs. The 500MHz version was available in PPGA packaging only.

Coppermine

In the spring of 2000 the packaging picture became even more complicated with the announcement of the first Celeron processors derived from Intel's 0.18-micron Pentium III Coppermine core. These were produced using yet another form factor - Intel's low-cost FC-PGA (flip-chip pin grid array) packaging. This appeared to mark the beginning of a phasing out of both the PPGA and Slot 1 style of packaging, with subsequent Pentium III chips also supporting the FC-PGA form factor. New Socket 370 motherboards were required to support the new FC-PGA form factor. Pentium III processors in the FC-PGA had two RESET pins, and required VRM 8.4 specifications. Existing Socket 370 motherboards were henceforth referred to as "legacy" motherboards, while the new 370-pin FC-PGA Socket-370 motherboards were referred to as "flexible" motherboards.

At the time of its introduction the Coppermine-based Celeron ran at 566MHz. There were a number of speed increments up until 766MHz, at which point the next significant improvement in the Celeron line was introduced. This was in early 2001, when the 800MHz version of the CPU became the first to use a 100MHz FSB. By the time the last Coppermine-based Celeron was released in the autumn of 2001, speeds had reached 1.1GHz.