Laser 128 - Built-in I;O Devices and Interfaces

INPUT/OUTPUT PORTS
6. INPUT /OUTPUT PORTS
A computer on its own is just a calculating machin e. To
be use ful , it must be ab le to communicate with the real
world by some means. This is the j ob of the
Input / Output (abbrev i ated as 1/ 0) ports. In th e LASER
12 8/ I 28EX computer system, th ere are eig ht 1/ 0 ports
which correspond to the peripheral slots in an Apple
lie computer.
All the 1/ 0 ports have already been occupied by bui lt-
in 1/ 0 devices and interfaces for commonly u sed I/ 0
devices so that in most cases you do not need to
purchas e any o ther peripheral interface ca rd s.
Howeve r, if you n eed to install add ition al 1/ 0 devices
for some specia l app lic a tions, there is sti ll a way to do
it. On th e left side of yo ur computer is an ex pan sion
connector for plu gg in g in an int erface car d. W it h an
optional expans i on box, your computer can even support
two interface cards at the same tim e. This opens up
your computer system to almost all kinds of
app li ca tion s.
6.1 B uilt -in 1/0 devices a nd interfaces
A port number is assigned to each of the
built-in 1/0 devices an d interfaces as sh own
in t able 6-1.
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