NEC Advanced Personal Computer System Reference Manual page 19

Hardware Overview
1-4
The APC also offers an optional Graphics Adapter based on the NEC pPO 7220.
This self-contained single PCB plugs into the Main Unit and simplifies graphics
applications, such as area shading, simulated movement, and solid or dashed lines,
either straight or curved. By employing the Graphics Adapter with selected soft-
ware packages, you can generate graphs, bar graphs, and three~dimensional
pictures. .
Also optional are two NEC printers. The Dot Matrix Printer provides rapid, high
quality printing at a low cost. It prints in both directions at 100 characters per
second on a 80-to-136-character column width. It prints special and graphic charac-
ters as well as standard alphanumeric characters.
The other printer is the NEC Model 3530 Spinwriter®, which produces high quality
fully-formed characters. This printer features interchangeable print elements that
contain up to 128 characters and are offered in several dozen type styles and symbol
sets. It prints 35 characters per second at 10, 12, and 15 characters per inch or
proportional spacing. It also prints bidirectionally and offers word processor
functions, such as automatic underlining, shadowing, bold face printing, as well as
several paper-handling accessories.
The standard APC comes equipped with 128 KB of RAM, which resides on the
Processor PCB. With the optional memory-expansion kits, RAM can be expanded
to 640 KB.
The asynchronous, synchronous serial I/O communications adapter is a standard
feature of the APC. The interface is supported by the NEC 8251A Communications
Controller, a USART, that is used as a peripheral and is programmed by the
microprocessor to communicate using virtually any serial or parallel data-
transmission technique, at programmable baud rates. For communications inter-
face requirements beyond this standard controller, NEC offers special-purpose I/O
Controllers on plug-in boards.
The Keyboard is not housed in the Main Unit; it attaches to the rear of the Main
Unit with a single five-foot, coiled cable. The Keyboard has 109 keys, including a
numeric keypad and 22 programmable function keys that facilitate data and word
processing. Each function key has two shift-modes, making available 44 user-
definable functions with one or two keystrokes.
NOTE
Only 32 of the 44 user-definable functions can be character strings.