Motorola DSP96002 - Manual (Page 163)

MOTOROLA DSP96002 USER’S MANUAL 9 - 7
9.2.1 Internal Data RAMs
The on-chip X and Y Data RAMs occupy locations $00000000 to $000001FF in X and Y Data Memory
maps, respectively, and they are always enabled.
9.2.2 Internal Data ROMs
The X and Y Data Memory expansion mode is affected by the DE bit located in the OMR. The on-chip X
and Y Data ROMs occupy locations $00000400 to $000007FF in X and Y Data Memory maps, respectively,
when enabled by setting DE=1 in the Operating Mode Register. If DE=0, the on-chip Data ROMs are dis-
abled and the address range they previously occupied is now in external data memory.
The X and Y Data ROMs each occupy 1,024 locations. The X Data ROM contains a full cycle of cosine val-
ues while the Y Data ROM contains a full cycle of sine values. The sine and cosine values were generated
using the MC68881 IEEE floating-point coprocessor rounded to IEEE single precision floating-point using
the round to nearest mode.
When the internal Data ROMs are enabled (DE=1), the X and Y Data Memory locations in the address range
$00000200 to $000003FF are defined as internal. This address range is unpopulated and is reserved for
future expansion. When the internal Data ROMs are disabled (DE=0), the address range $00000200 to
$000003FF is defined as external.
X DATA Y DATA
$FFFFFFFF $FFFFFFFF
On-Chip External
Peripherals Peripherals
$FFFFFF80 $FFFFFF80
External External
X Data Y Data
Memory Memory
$000001FF $000001FF
Internal Internal
X Data RAM Y Data RAM
$00000000 $00000000
Figure 9-4. DSP96002 Data Memory Maps for DE=0