Tandy 1000 HX Technical Reference Manual page 275

• TANDY COMPUTER PRODUCTS
4 COLOR HIGH RESOLUTION 640 X 200 GRAPHICS MODE
The 4 Color High Resolution 640 X 200 Graphics mode may
require a high resolution monitor for proper operation.
Only supported on the IBM PCjr, this mode has the following
characteristics:
Contains a maximum of 200 rows of 640 PELs
Can display 4 of 16 possible colors
Each pixel selects 1 of 4 colors
Requires 32K bytes of read/write memory
Formats 8 PELs per two bytes (1 even byte and 1 odd
byte) in the following manner:
EVEN BYTES
7 6 5
PA0 PA0 PA0
First
Display
PEL
Second
Display
PEL
PAl PAl
7 6
ODD BYTES
Third
Display
PEL
PAl
5
4
PA0
Fourth
Display
PEL
PAl
4
3
PA0
Fifth
Display
PEL
PAl
3
2
PA0
Sixth
Display
PEL
PAl
2
1
PA0
Seventh
Display
PEL
PAl
1
0
PA0
Eighth
Display
PEL
PAl
0