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Post by mirkosoft on Oct 13, 2015 0:57:46 GMT
Hi!
Like all of us know that VDC 8568 (DCR VDC revision 2 chip with additional 38th register) can produce EGA mode 640×350 non interlaced. 38th register can select polarity of signal which is safe for EGA monitors, but standard Commodore monitors like 1084, 1902 etc... can not handle and crashes forever. Long long time I was using LCD displays or other display option for my DCR but since I'm working more and more with lightpen I must to use 1084 monitor 'cause converters changes timing and LCD disables lightpen access. Now is for me big Q 'cause I was owner of Commodore monitor long long time ago and at that time I didn't knew anything about 8568 EGA and 38th register. I want to use EGA mode without damage 1084 - my DCR is connected to three display devices: LCD, CRT (PC monitor) and Commodore 1084S-P... Q: Is safe only to leave 1084 turned off or must to be signal cable connected also removed? I know that I'm asking like little kid, but I have not lot of money to get new 1084 - so this Q has real base...
Thank you all for reading it and each help.
Miro
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Post by hydrophilic on Oct 13, 2015 8:11:06 GMT
I don't think 1084 will correctly "sync" with reversed polarity. If the monitor doesn't sync, then it is running "open loop" and should be safe. I do not own 1084 (and my 1902 stopped working long ago), so I can't be 100% sure. What I can say, is that if your monitor does "sync" to a frequency it can not handle, then your monitor could be damaged. Any V-frequency between 50~66 should be safe, and any H-frequency around 15~16 kHz should be safe. In other words, don't try to connect 1084 to 32kHz video source... well Amiga has better resolution than C128, so maybe it would be okay... does anybody know H-frequency for Amiga? That would answer the question! If in doubt, turn it off! Shipping of monitors is expensive and risky... and CBM monitors get harder to find all the time
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Post by mirkosoft on Oct 13, 2015 8:18:24 GMT
OK, simplest Q: I turn it off. Must I remove also RGBI data (video signal) cable?
Miro
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Post by hydrophilic on Oct 13, 2015 8:21:16 GMT
You can keep cable connected.
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Post by robertb on Oct 15, 2015 5:11:26 GMT
does anybody know H-frequency for Amiga? That would answer the question! 15 KHz Trying to finish uploading all the Amiga 30th videos before the Amiwest Show next weekend, Robert Bernardo Fresno Commodore User Group www.dickestel.com/fcug.htm
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