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IV PC Technology Evolution
Standing in the year 1983,
The IBM PC, a "portable competitor"
and The Macintosh.
A computer interface using
icons was obviously so much more intuitive that both IBM and
Microsoft each had plans of their own for an icon-based operating
system. IBM released their version known as TopView,
while Microsoft called their graphical operating system
Windows. Today we call these operating systems with icons,
the GUI (graphical user interface).
IBM's desire to distance itself from
Microsoft with TopView did little to help the cooperative effort for
a next generation operating system called OS/2.
The final tear in the relationship
was IBM's insistence that OS/2 run on the 80286 CPU (the marketing name
for this 1985 entry was the IBM AT, or Advanced Technology).
Microsoft was convinced that the entry point for the new operating system
should be based on the much more advanced 80386 CPU.
8-bit verses 16-bit Data Paths
To stay backwards compatible with the PC, the AT introduced a 16-bit ISA data path by adding a second connector to the 8-bit ISA slot. This way older cards could be retained and used as 8-bit components.
Figure 2: 8-bit & 16-bit cards. The contacts of the card connect to a slot. See the difference between the shorter 8-bit card and the longer 16-bit card.
Types of Switches
Even with todays Plug and Play, sometimes a device needs to have a configuration set. There are two typical ways to accomplish this. One is with switches the second is with jumpers.
Figure 3: A typical switch block. On and off can quickly be changed with a ballpoint pen.
When you want to keep a jumper attached to a device without it completing a circuit, you hang it (attach it) on one connector. This is sometimes called parking the jumper.