STV942x

The STV942x PageEditor softwareshows on justone screen the contents of the OSDdevice registers and RAM.

The screen of STV942x is divided in two parts :
Left Part : The OSDRAM
STV942x is made of 16 lines of 32 positions, for a total of 512 positions. Each position represents 2 bytes of RAM and it can be edited with the OSD RAM
Editor. When starting the OSD Page Editor, the RAM is blanked.
One position can hold :
 - Acharacter code : one byte for the code, one byte for the attributes,
 - A text descriptor, containing, in two bytes, the address of one line of characters,
 - A vertical space descriptor, containing, in two bytes, the number of space lines,
 - One line of a user defined character, in two bytes.
   A complete user defined character takes 18 lines, or 36 bytes.

Right Part : The OSD Registers
It showsthe contentsof the 12 registers of theOSD device. Each register can be edited with the command "F1".When startingtheOSDPageEditor, the registers are initialized with default values that are well suited for a VGAapplication.

During the OSD Page Editor Execution, when a RAM position, or a Register is edited, the OSD device is updated through the parallel port of the PC and the I²C interface.