Silicon Chip Color TV Pattern Generator (June - July 1997)

[santosp]

Hello.
If anyone have something like this, either from Altronics either from Jaycar either direct from Silicon Chip magazine, please let me know.
I would like very much to compare the eprom content as to check if mine have the right checksum.

Thank you in advance.

 

[austfox]

Looks like an interesting project. The ZIP file with the QuickBasic programs to write to the ROM is available from the Silicon Chip website.

Navigate to Shop, Software, and then search 'Colour TV'.

 

[santosp]

Hi, thank you for your response. I have already the files in my possession.
I just would like to compare what my vintage pc wrote to eprom via the parallel port, because I am facing some problems in operation of the circuit.

 

[austfox]

Just checking also that you have seen the errata for the project:

Colour TV Pattern Generator, June & July 1997: The patterns produced by the TV Pattern Generator are slightly off-centre on the TV screen due to a slight displacement in the line sync signal. In most cases, the normal over-scanning of each line on the TV screen will mask out this small shift.

It can be corrected by adding an RC network to delay the line sync by the requisite 1.5µs. This involves adding a 4.7kΩ resistor between the D7 output of IC1 at pin 11 and the sync input of IC10 at pin 16. The pin 16 input of IC10 is bypassed to ground with a 270pF capacitor. The resistor is best placed instead of the link on the PC board above the three 330Ω resistors near IC10. Note that

IC10 has an incorrect pin 1 labelling on the PC board. The position shown for pin 1 is actually pin 16. The capacitor can connect from pin 16 to pin 1 of IC10 on the underside of the PC board.