Fig. 6 - The timing of command signals
In order to easier calculate the address of any pixel as well as the
address of the associated color attribute, we divide the 256x192 px image (or
32x24 characters) as follows:
— horizontally
— 8 adjoined pixels, 8-bit encoded (
B7—B0
) make up
one character;
— the image contains 32 characters, 5-bit encoded:
C4, C3, C2, C1, C0
;
— vertically
— 8 sequential TV lines, 3-bit encoded
L2, L1, L0
,
make up one character;
— 8 character rows, 3-bit encoded
R2, R1, R0
make
up one third of the image;
— the image contains 3 thirds, 2-bit encoded
T1
,
T0
,
the “11” combination not being used.
The address of the byte containing bit B of character C, line L, row R and
third T can be found using formula
(1)
, and the address of the associated color
attribute can be found using formula
(2)
where:
13
Содержание CoBra
Страница 20: ...Fig 10 Keyboard schematic 20 ...
Страница 21: ...Fig 11 Keyboard schematic 21 ...
Страница 23: ...Fig 13 Power source schematic 23 ...
Страница 39: ...9 APPENDIX 1 CoBra Microcomputer Schematics 39 ...
Страница 40: ...Fig A1 1 CoBra Microcomputer Central Processing Unit 40 ...
Страница 41: ...Fig A1 2 CoBra Microcomputer Configurator and Selector Circuit 41 ...
Страница 42: ...Fig A1 3 CoBra Microcomputer Read Only Memory Circuit 42 ...
Страница 43: ...Fig A1 4 CoBra Microcomputer DRAM Memory Circuit 43 ...
Страница 44: ...Fig A1 5 CoBra Microcomputer Memory Access Prioritizer and Command Logic 44 ...
Страница 45: ...Fig A1 6 CoBra Microcomputer Video Address Generator Circuit 45 ...
Страница 46: ...Fig A1 7 CoBra Microcomputer Video Address Multiplexer Circuit 46 ...
Страница 47: ...Fig A1 8 CoBra Microcomputer Video Memory Circuit 47 ...
Страница 48: ...Fig A1 9 CoBra Microcomputer Video Sync Pulses Generator Circuit 48 ...
Страница 49: ...Fig A1 10 CoBra Microcomputer Video Signal Shape Generator 49 ...
Страница 50: ...Fig A1 11 CoBra Microcomputer Interfaces 50 ...
Страница 51: ...Fig A1 12 CoBra Microcomputer Voltage Level Adapter Circuits 51 ...
Страница 52: ...Fig A1 13 CoBra Microcomputer Keyboard Interfacing Circuit 52 ...
Страница 53: ...Fig A1 14 CoBra Microcomputer TV Monitor Interfacing Circuit 53 ...
Страница 55: ...10 APPENDIX 2 Flopppy Disk Interface Schematics 55 ...
Страница 56: ...Fig A2 1 Floppy Disk Interface Disk Controller 56 ...
Страница 57: ...Fig A2 2 Floppy Disk Interface Command and Control Signals Generator Circuits 57 ...
Страница 58: ...Fig A2 3 Floppy Disk Interface Write Clock and Digital PLL Circuits 58 ...
Страница 59: ...10 APPENDIX 3 Component Placement on Boards 59 ...
Страница 60: ...60 Fig A3 1 Component Placement on Keyboard Circuit Board ...
Страница 61: ...61 Fig A3 3 Keyboard Circuit Board top layer seen from above keys side ...
Страница 62: ...62 Fig A3 3 Keyboard Circuit Board bottom layer seen from above keys side ...
Страница 63: ...Fig A3 5 Component placement on the floppy interface board 63 ...