
Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
111
4 Hardware Architecture
(continued)
4.14 System and External Memory Interface
(SEMI)
(continued)
4.14.4 Registers
(continued)
4.14.4.3 Segment Registers
The external program and data memory components
(EROM, ERAM, and EIO) can each be expanded for
each core through a combination of registers and pins.
The ESEG[3:0] pins (see
Section 4.14.1
) reflect the
value of the
EXSEG0
,
EXSEG1
,
EYSEG0
, or
EYSEG1
external segment registers for a given external access.
A user’s program executing in either core can write to
these registers to expand the external ERAM and
EROM data components. The value written to any one
of these registers is driven onto the ESEG[3:0] pins for
a corresponding memory component as described
below and can be interpreted by the system as an
address extension (EA[22:19], for example) or as
decoded enables.
The SEMI drives bits 3:0 of the 16-bit
EXSEG0
register
onto the ESEG[3:0] pins at the same time as it drives
the address onto EA[18:0] for an external ROM
(EROM) access from CORE0.
The SEMI drives bits 3:0 (for ERAM) or bits 7:4 (for
EIO) of the 16-bit
EYSEG0
register onto the ESEG[3:0]
pins at the same time as it drives the address onto
EA[18:0] for an external RAM (ERAM or EIO) access
from CORE0.
The SEMI drives bits 3:0 of the 16-bit
EXSEG1
register
onto the ESEG[3:0] pins at the same time as it drives
the address onto EA[18:0] for an external ROM
(EROM) access from CORE1.
The SEMI drives bits 3:0 (for ERAM) or bits 7:4 (for
EIO) of the 16-bit
EYSEG1
register onto the ESEG[3:0]
pins at the same time as it drives the address onto
EA[18:0] for an external RAM (ERAM or EIO) access
from CORE1.
Table 61. EXSEG0 (CORE0 External X Segment Address Extension) Register
The memory address for this register is 0x40004.
Table 62. EXSEG1 (CORE1 External X Segment Address Extension) Register
The memory address for this register is 0x40008.
15—4
Reserved
3—0
XSEG0[3:0]
Bit
15—4
3—0
Field
Reserved
XSEG0[3:0] External segment address extension for X-memory accesses to EROM by
CORE0.
Description
R/W
R/W
R/W
Reset Value
0
0
Reserved—write with zero.
15—4
Reserved
3—0
XSEG1[3:0]
Bit
15—4
3—0
Field
Reserved
XSEG1[3:0] External segment address extension for X-memory accesses to EROM by
CORE1.
Description
R/W
R/W
R/W
Reset Value
0
0
Reserved—write with zero.