P
ackaging your CPU inside a big box before slotting it
into your motherboard seems like a recipe for a
thermal catastrophe now, but for a brief period
around the turn of the Millennium, Intel (and later AMD)
mounted their CPUs on circuitboards inside sleek black
packages. They looked great too. There was now room for
proper logos and a flashy physical design. Instead of dropping
a nondescript-looking ceramic square into your motherboard,
you had a fancy black box with a hologram on the front.
With their slick packaging, the first Pentium II CPUs looked
great in the TV adverts and promo shots. I remember wanting
one just because they looked so good – a small hologram
sticker clearly goes a long way towards manipulating people
like me! To the uninformed, it looked like these attractive
slot-based CPUs were the way of the future, but if you took a
peek inside the box, they were clearly a result of technological
limitations at the time.Cache for questions
To understand the need for slot processors, we need to start
by going back a bit further in time. Before the Pentium II, Intel
had two major CPU designs. It had the Socket 7 Pentium
MMX for consumer PCs, which was the last gasp for the
first Pentium design, now running at up to 233MHz. MMX
stands for multimedia extensions, and it effectively enabled
a lot more functions to be handled in software on the CPU,
rather than in hardware. For example, an MMX CPU enabled
you to properly use a software PCI modem, rather than a full
hardware one, saving you some money.
For servers and workstations, Intel had also introduced the
Pentium Pro, a massive chip that was heavily geared towards
pure 32-bit computing. It lacked consumer frills such as MMX
instructions, but you could run more than one Pentium Pro in
parallel on a multi-socket board.
The Pentium Pro also had a massive L2 cache that ranged
between 256KB and 1MB, depending on the
model. At this time, there was no way to integrate
this cache directly into the CPU die, but the
Pentium Pro did incorporate its huge L2 cache
in the same Socket 8 package as the CPU die,
and it also ran the cache at the same speed
as the CPU. There was a big problem with this
approach at the time though – making these
Socket 8 packages with full-speed cache was an
expensive process, and there were low yields.
Intel wanted to combine the two ideas,
making a desktop CPU with loads of L2 cache,
as well as consumer features such as MMX.
It also needed to be better at executing 16-bit
code (which was still used by some software
at the time) than the Pentium Pro and, most
importantly, it needed to be affordable to
manufacture on a large scale.
This meant compromising, as Intel knew it
couldn’t practically equip a mainstream desktop
CPU with loads of full-speed cache in a socketRETRO TECH / ANALYSIS
Slot
machines
Holograms, black boxes and mountains of cache. Ben Hardwidge recalls
the weird moment in time when Intel’s CPUs came in Slot 1 format
An original SECC
Pentium II – look at
the size of the cache
chips on either side
of the CPU areaP
ackagingyourCPUinsidea bigboxbeforeslottingit
intoyourmotherboardseemslikea recipefora
thermalcatastrophenow,butfora briefperiod
aroundtheturnoftheMillennium,Intel(andlaterAMD)
mountedtheirCPUsoncircuitboardsinsidesleekblack
packages.Theylookedgreattoo.Therewasnowroomfor
properlogosanda flashyphysicaldesign.Insteadofdropping
a nondescript-lookingceramicsquareintoyourmotherboard,
youhada fancyblackboxwitha hologramonthefront.
Withtheirslickpackaging,thefirstPentiumII CPUslooked
greatintheTVadvertsandpromoshots.I rememberwanting
onejustbecausetheylookedsogood– a smallhologram
stickerclearlygoesa longwaytowardsmanipulatingpeople
likeme!Totheuninformed,it lookedliketheseattractive
slot-basedCPUswerethewayofthefuture,butif youtooka
peekinsidethebox,theywereclearlya resultoftechnological
limitationsatthetime.Cacheforquestions
Tounderstandtheneedforslotprocessors,weneedtostart
bygoingbacka bitfurtherintime.BeforethePentiumII, Intel
hadtwomajorCPUdesigns.It hadtheSocket7 Pentium
MMXforconsumerPCs,whichwasthelastgaspforthe
firstPentiumdesign,nowrunningatupto233MHz.MMX
standsformultimediaextensions,andit effectivelyenabled
a lotmorefunctionstobehandledinsoftwareontheCPU,
ratherthaninhardware.Forexample,anMMXCPUenabled
youtoproperlyusea softwarePCImodem,ratherthana full
hardwareone,savingyousomemoney.
Forserversandworkstations,Intelhadalsointroducedthe
PentiumPro,a massivechipthatwasheavilygearedtowards
pure32-bitcomputing.It lackedconsumerfrillssuchasMMX
instructions,butyoucouldrunmorethanonePentiumProin
parallelona multi-socketboard.
ThePentiumProalsohada massiveL2cachethatranged
between256KBand1MB,dependingonthe
model. At this time, there was no way to integrate
this cache directly into the CPU die, but the
Pentium Pro did incorporate its huge L2 cache
in the same Socket 8 package as the CPU die,
and it also ran the cache at the same speed
as the CPU. There was a big problem with this
approach at the time though – making these
Socket 8 packages with full-speed cache was an
expensive process, and there were low yields.
Intel wanted to combine the two ideas,
making a desktop CPU with loads of L2 cache,
as well as consumer features such as MMX.
It also needed to be better at executing 16-bit
code (which was still used by some software
at the time) than the Pentium Pro and, most
importantly, it needed to be affordable to
manufacture on a large scale.
This meant compromising, as Intel knew it
couldn’t practically equip a mainstream desktop
CPU with loads of full-speed cache in a socketRETRO TECH / ANALYSIS
Slot
machines
Holograms, black boxes and mountains of cache. Ben Hardwidge recalls
the weird moment in time when Intel’s CPUs came in Slot 1 format
An original SECC
Pentium II – look at
the size of the cache
chips on either side
of the CPU area