Early Vintage Computer Buses Have Their Influences On Your Computer Today

erm “expansion bus “is a frequentChannel Architecture (MSA) and Extended
term in vintage computer terminology whichIndustry Standard (EISA) bus systems.
requires elaboration. Much of the legacy of vintageIndustry Standard Architecture (ISA). This was
bus systems are in our current computerthe original AT bus also called an ISA bus. It was
systems today.the original 8 bit IBM PC bus which was bumped
To begin with the “expansion bus" is aup to 16 bits at some point in its later
data highway for computer data information todevelopment. Fine for a 16 bit 286 or very early
travel on: the bandwidth is in essence the number386 computers
of lanes. The bigger the bandwidth the more dataMicro Channel Architecture (MSA). This was an
can be sent. As examples, an 8 megabyteearly 32 bit bus system which was not received
bandwidth means that data can be sent in 8 bitswell but set the stage for an industry consortium
chunks. Our current systems use between 32 bitof the major non IBM computer manufacturers (
and now 64 bit bandwidth.at the time referred to as “The Group of
An expansion bus is where cards connect to theNine) to develop the EISA standard bus.
computer; Cards have an expansion edge, whichExtended Industry Standard Architecture (EISA).
fits snugly into the bus much like an electrical plugThe EISA bus standard was a standard of its
fits into a wall socket.own right which was 32 bit, included bus
When cards are plugged into the bus, theymastering and importantly remained compatible
communicate with the system, sometimeswith previous older expansion cards. 32 bit
through the BIOS and others not. (The BIOS issystems were first to incorporate in later 386
the basic input /output system that tells thesystems. The 486 line solidified and standardized
computer how to move data from the differentthe 32 bit systems in the established software of
components.) The 8, 16 or 32 bit bandwidth is anthe day.
important consideration due to communicationBackward compatibility at the time was a novel
time between the cards. For example you have anew concept which has remained an important
16 bit vintage 286 PC and it is sending out data atconsideration in the computer industry.
16 bits a: your video card is also 8 bits. If youEISA slots would accommodate both the ISA and
have an older 8 bit bus, such as in early IBM PCsEISA expansion slots to allow hardware upgrades,
and clones, the bus will become a bottleneck inHowever the EISA expansion boards would be of
the system; it is like having a 4 lane highwaylittle advantage and would seldom work in the
connected to another 4 lane highway by way ofolder ISA expansion slots.
a 1 lane road. At most times regardless of theOn the other hand the Micro Channel setup was
faster 4 lane highway traffic will be slow –not backward compatible. On the one hand the
limited by the single lane connection road.Micro Channel developers were free to initiate
There were basically 3 types of expansion busnew radical changes in computer development and
available in vintage computers: ISA, MCA, EISAhardware which would have allowed for major
systems.new useful features in computer software.
Each early development in major ways paved theHowever owners of previous systems would
way for the later systems which indeed we takehave been left with then obsolete vintage useless
for granted today. This was both in terms ofhardware which would have been of no use and
hardware and basic concepts in our computercertainly little financial value.
systems and technology as well as computerHence there was a lot of resistance to the Micro
marketing that we take for granted today asChannel bus setup.
simple basic facts of life without any considerationIt died a lingering death with its legacy living on in
due.the aspirations of features offered in future
Basically the newer buses offered increaseddevelopments and standards.
performance over the older technology buses.Thus the die was set for future hardware
The basic explanations of the buses are asstandards and software function as well as
follows:standard computer marketing concepts that we
The 3 bus standards to note were Industrytake for granted like mother’s milk today.
Standard Architecture (ISA) .Micro Channel