p87c770aar NXP Semiconductors, p87c770aar Datasheet - Page 48

• Manufacturer Part Number: p87c770aar
• Description: Microcontrollers Ntsc With On-screen Display Closed Caption
• Manufacturer: NXP Semiconductors

Philips Semiconductors
18.6
All registers and RAM in the display section are mapped into the upper 32-kbyte external RAM range of the 80C51 core.
When writing to the display section, memory units (CLUT and the Display RAM) have wider formats than 8-bits.
Two bytes are written for each word, the first byte (even addresses), addresses the lower 8-bits; the lower nibble of the
second byte (odd addresses), addresses the upper 4-bits.
18.6.1
The memories can be accessed by the microprocessor as if it is external RAM.
1999 Jun 11
Microcontrollers for NTSC TVs with On-Screen
Display (OSD) and Closed Caption (CC)
Memory mapping
A
CCESSING MEMORY
handbook, halfpage
handbook, halfpage
7
7
processor byte n
processor byte n
Fig.20 Memory and register mapping.
display data
(16 bytes)
(32 bytes)
scroll map
character
registers
2 bytes/
CLUT
3
Fig.19 Byte mapping.
microcontroller
address
87FFH
87F0H
871FH
845FH
801FH
8700H
8020H
8000H
1
0
0
48
(1120 bytes)
display data
CLUT RAM
11
RAM
registers
character data
internal RAM
address
22FH
000H
F
0
F
0
MGL152
MGL149
0
P8xCx70 family
Product specification