Datasheet

Propeller™ P8X32A Datasheet www.parallax.com

5.0 MEMORY ORGANIZATION

5.1. Main Memory

The Main Memory is a block of 64 K bytes (16 K longs)

that is accessible by all cogs as a mutually-exclusive

resource through the Hub. It consists of 32 KB of RAM

and 32 KB of ROM. Main memory is byte, word and long

addressable.

5.1.1. Main RAM

The 32 KB of Main RAM is general purpose and is the

destination of a Propeller Application either downloaded

from a host or from the external 32 KB EEPROM.

5.1.2. Main ROM

The 32 KB of Main ROM contains all the code and data

resources vital to the Propeller chip’s function: character

definitions, log, anti-log and sine tables, and the Boot

Loader and Spin Interpreter.

5.1.3. Character Definitions

The first half of ROM is dedicated to a set of 256

character definitions. Each character definition is 16

pixels wide by 32 pixels tall. These character definitions

can be used for video generation, graphical LCD's,

printing, etc.

The character set is based on a North American / Western

European layout, with many specialized characters added

and inserted. There are connecting waveform and

schematic building-block characters, Greek characters

commonly used in electronics, and several arrows and

bullets. (A corresponding Parallax True-Type Font is

installed with and used by the Propeller Tool software,

and is available to other Windows applications.)

The character definitions are numbered 0 to 255 from left-

to-right, then top-to-bottom, per Figure 7 below. They are

arranged as follows: Each pair of adjacent even-odd

characters is merged together to form 32 longs. The first

character pair is located in $8000-$807F. The second pair

occupies $8080-$80FF, and so on, until the last pair fills

$BF80-$BFFF.

Figure 7: Propeller Font Character Set