Epson 4500 - Manual (Page 178)

The Interface Boards
A number of optional interfaces are available in case your computer is
either not provided with a parallel interface or you wish to increase the
memory capacity of your printer’s buffer.
Choosing an Interface
Optional interfaces can be divided into three main categories which are
described briefly below.
IEEE-488 interfaces offer standardized connections, trouble-free
operation, and the ability to connect computers, printers, and other
devices on the same line so that they may share data freely.
The buffered parallel interfaces also offer trouble-free operation and
standardized connections. They provide the printer with more
memory to free the computer for other tasks when printing large
amounts of text or graphics. You can increase the printer’s data
buffering capacity by an additional 32 KB (about 10 pages).
Serial interfaces are required if your computer is not equipped with
a parallel interface or if you need an interface that conforms to the
Current Loop standard instead of RS-232C. These interfaces also
provide some combination of the following features: X-ON/X-OFF
data communication protocol, loopback self test modes, and data
buffers that increase the printer’s data buffering capacity.
5-40 Using the Printer Options