Propeller Manual

1: Introducing the Propeller Chip
Each cog has its own RAM, called Cog RAM, which contains 512 registers of 32 bits each.
The Cog RAM is all general purpose RAM except for the last 16 registers, which are special
purpose registers, as described in Table 1-3. The Cog RAM is used for executable code, data,
variables, and the last 16 locations serve as interfaces to the System Counter, I/O pins, and
local cog peripherals.
When a cog is booted up, locations 0 ($000) through 495 ($1EF) are loaded sequentially from
Main RAM / ROM and its special purpose locations, 496 ($1F0) through 511 ($1FF) are
cleared to zero. After loading, the cog begins executing instructions, starting at location 0 of
Cog RAM. It will continue to execute code until it is stopped or rebooted by either itself or
another cog, or a reset occurs.
Table 1-3: Cog RAM Special Purpose Registers
Cog RAM Map Address Name Type Description
$1F0
PAR
Read-Only
1
Boot Parameter, p. 178, 331
$1F1
CNT
Read-Only
1
System Counter, p. 73, 282
$1F2
INA
Read-Only
1
Input States for P31–P0, p. 118, 297
$1F3
INB
3
Read-Only
1
Input States for P63–P32, p. 118, 297
$1F4
OUTA
Read/Write Output States for P3–P0, p. 175, 330
$1F5
OUTB
3
Read/Write Output States for P63–P32, p. 175, 330
$1F6
DIRA
Read/Write Direction States for P31–P0, p. 104, 456
$1F7
DIRB
3
Read/Write Direction States for P63–P32, p. 104, 456
$1F8
CTRA
Read/Write Counter A Control, p. 95, 288
$1F9
CTRB
Read/Write Counter B Control, p. 95, 288
$1FA
FRQA
Read/Write Counter A Frequency, p. 111, 293
$1FB
FRQB
Read/Write Counter B Frequency, p. 111, 293
$1FC
PHSA
Read/Write
2
Counter A Phase, p. 180, 332
$1FD
PHSB
Read/Write
2
Counter B Phase, p. 180, 332
$1FE
VCFG
Read/Write
Video Configuration, p. 213, 366
$1FF
VSCL
Read/Write Video Scale, p. 216, 367
Special
Purpose
Registers
(16 x 32)
General
Purpose
Registers
(496 x 32)
$000
|
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$1EF
$1F0
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$1FF
Note 1: For Propeller Assembly, only accessible as a source register (i.e., mov dest, source). See the
Assembly language sections for
PAR, page 331; CNT, page 282, and INA, INB, page 297.
Note 2: For Propeller Assembly, only readable as a source register (i.e.,
mov dest, source); read
modify-write not possible as a destination register. See the Assembly language section
for PHSA, PHSB on page 332.
Note 3: Reserved for future use.
Propeller Manual v1.1 · Page 23