-
the ROM in the P: memory space. PS* is used to select A17 to provide
an additional 128k bytes of space in Dx: memory space for the ROM.
The ADSIC internal registers are decoded internally and start at $E000
in Dy:. These registers are decoded using A0-A2, A13-15, and PS* from
the DSP. The ADSIC internal registers are 16 bit wide so only D8-D23
are used.
The DSP program code is stored in the FLASH ROM U404. During
normal modes of operation, the DSP moves the appropriate program
code into the three SRAMs U402, U403, and U414 and internal RAM
for execution. The DSP never executes program code from the FLASH
ROM itself. At power-up after reset, the DSP downloads 512 words
(1536 bytes) from the ROM starting at $C000 and puts it into the
internal RAM starting at $0000 where it is executed. This segment of
Figure 13 . Vocoder Memory Mapping
$0000
$01FF
$0FFF
$0200
$1000
$1FFF
$E000
$DFFF
$2000
$7FFF
$FFFF
$8000
DyDxP
ADS Vectors
ADSIC
Registers
$9FFF
$A000
External ROM
16KB Physical
Banks
$00000-1FFFF
Internal P Ram
ADS P Ram
External ROM
16KB Physical
Banks
$20000-3FFFF
Internal X Rom
Internal Y Rom
Internal Dx Ram
ADS Dx Ram
Internal Dy Ram
ADS Dy Ram
External
RAM
U403
External
RAM
U402
External
RAM
U414
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