83C145 Datasheet, PDF (30/40 Pages) NXP Semiconductors – Microcontrollers for TV and video MTV

Philips Semiconductors
Microcontrollers for TV and video (MTV)
Product specification
83C145; 83C845
83C055; 87C055
15 PROGRAMMING THE OSD EPROM
15.1 Overview
The OSD EPROM space starts at location C000H and
ends at location CFFFH. However, due to the addressing
scheme of the OSD, not all locations within this space are
used.The start location of the next character can be
calculated by adding 40H to the start location of the
previous character. For example, character 1 starts at
C000H; then characters 2, 3, and 4 start at C040H,
C080H, and C0C0H, respectively.
15.2 Character description and programming
An example of an OSD character bit map, and the program
data to obtain that character is shown in Table 34.
Each character is 14 bits wide by 18 lines high.A character
is split about a vertical axis into two sections UPPER and
LOWER as illustrated in Table 34:
• Each section contains 7 bits of the character, such that:
– the LOWER section contains bits 7 to 1, and
– the UPPER section contains bits 14 to 8.
• The LOWER section of the character is programmed
when the LSB of the program address equals a logic 0,
and the UPPER section when the LSB equals a logic 1.
During Programming and Verification, each section is
programmed using bytes of program data. The MSB of the
program data is not used; however, the MSB location
physically exists, and so will Program and Verify.
15.3 OSD EPROM bit map
The mapping for the full OSD EPROM is shown in Table 35. To program the example character into the first character
location of the OSD EPROM would require the data at the address as shown in Table 34.
Table 34 Example of an OSD Character Bit Map (note 1)
LINE
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
Line 11
Line 12
Line 13
Line 14
Line 15
Line 16
Line 17
Line 18
CHARACTER BIT MAP
UPPER
(BIT 14 TO 8)
LOWER
(BIT 7 TO 1)
000 0000
000 0000
001 1110
001 1110
001 1110
001 1110
001 1110
001 1110
001 1111
001 1111
001 1111
001 1110
001 1110
001 1110
001 1110
001 1110
000 0000
000 0000
000 0000
000 0000
000 1100
000 1100
000 1100
000 1100
000 1100
000 1100
111 1100
111 1100
111 1100
000 1100
000 1100
000 1100
000 1100
000 1100
000 0000
000 0000
PROGRAM DATA
UPPER
LOWER
X000 0000
X000 0000
X001 1110
X001 1110
X001 1110
X001 1110
X001 1110
X001 1110
X001 1111
X001 1111
X001 1111
X001 1110
X001 1110
X001 1110
X001 1110
X001 1110
X000 0000
X000 0000
X000 0000
X000 0000
X000 1100
X000 1100
X000 1100
X000 1100
X000 1100
X000 1100
X111 1100
X111 1100
X111 1100
X000 1100
X000 1100
X000 1100
X000 1100
X000 1100
X000 0000
X000 0000
Note
1. X can be a logic 0 or logic 1, and will Program and Verify correctly.
ADDRESS (HEX)
UPPER
LOWER
C001
C003
C005
C007
C009
C00B
C00D
C00F
C011
C013
C015
C017
C019
C01B
C01D
C01F
C021
C023
C000
C002
C004
C006
C008
C00A
C00C
C00E
C010
C012
C014
C016
C018
C01A
C01C
C01E
C020
C022
1996 Mar 22
30