Amigan kuva VGA-näytöllä

Kirjoittaja Viesti   ooiu Lauantaina, 7. joulukuuta, 2002 - klo 12.42:    Millä vimmatulla saan kuvan näkymän kunnolla? Laiton amigan kiinni vanhaan VGA-monitoriin VGA-adaperilla ja näytöllä näkyy muutama kuva päällekäin. Resoluutiossa on siis varmaan jotain vikaa. Olen säätänyt niitä kohdalleen Prefs->screenmodesta, mutta ei auta. Mikään ei tunnu muuttuvan kun vaihdan resoluutiota.   Flux Lauantaina, 7. joulukuuta, 2002 - klo 12.49:    Tavallinen vga-putki tahdistuu vain yli 30kHz juovataajuuksiin. ECS- ja AGA-piirisarjoissa on valmiina sopivia tiloja. Monet softat ja varsinkin pelit ja demot käyttävät vain PAL-taajuuksia, jolloin tarvitaan scandoubler eli pelkkä adapteri ei piisaa.   ooiu Lauantaina, 7. joulukuuta, 2002 - klo 12.55:    Flux: Mistähän scandoubler saa?   Flux Lauantaina, 7. joulukuuta, 2002 - klo 13.09:    Seuraat sakun myyntipalstaa tai laitat itse ostoilmoituksen. Itse metsästin siten A1200:lle sisäisen scandoublerin. A2000:lle löysin muualta Impact Vision 24 -videoeditointikortin, jossa on myös scandoubler. Tosin se piti modata A2000:lle, koska oli A4000-versio eikä mukana ollut A2000-adapteria. Katso tämän alueen debatit "Ulkoinen scandoubler" ja "Kortteja".   icaros Sunnuntaina, 8. joulukuuta, 2002 - klo 19.20:    Onkos muuten kukaan tehnyt scandoubleria itse? Koska siihenhän löytyy rakennusohjeet...   icaros Sunnuntaina, 8. joulukuuta, 2002 - klo 19.26:    Eikunjoo, sehän onkin syncdoubler. No kuitenkin... Aminetistä pitäs löytyä "hard/hack/Syncdoubler.lha" "Show 15khz on VGA Monitor, no Patch" ---niks naks, oujee--- Syncdoubler II description, 05.09.98 In 1996 I changed my multisync monitor to a VGA monitor. I thought this is no problem because I didn't use the PAL Hires mode. But: - many programs open Hires screens without a question - Hires screen if errors in startup sequence - bootmenu in Hires - etc. Hires screen on a VGA monitor? This won't work! Where's the difference between a Hires mode and a VGA mode ? In Hires one line on screen is 64 us (micro seconds) long, the horizontal frequenzy is (64 us)^-1 = 15625 Hz. VGA Monitors begins with the double frequency, 31250 Hz, one VGA line is 32 us long or shorter. My idea was to add one horizonal sync every Hires line. This should be enough for the monitor to sync correctly. Because the complete Hires line is still 64 us long and the time between two syncs is 32 us, the line is wrapped in two lines on the monitor. --> Kuddelmuddel on the screen ! So I had to blank every second line on the monitor for a correct picture. My first syncdoubler was a quick test for my idea, and it worked. I used a dual retriggerable monostable multivibrator called 74HC123 for creating the second necessary sync. The delay was controlled by a RC combination, I have to say this was really no optimum. Every second line was muted by shortening the RGB lines with 3 transistors, not gentleman like, but it works and it was quick and cheap. This worked but was not really usable, so I had to create a new Syncdoubler, the Syncdoubler II. The Syncdoubler II uses two logic components, one quad NAND and a PIC microcontroller. The microcontroller is clocked by the c1 clock from the amiga (about 3,54 MHz), the timing of the hsync is controlled by the PIC software. This syncdoubler allows to scroll through the amiga screen in a resolution of 16 steps through two push buttons. The RGB signal is muted through the PIC. (have a look on the schematic, If you don't like this method use a RGB switch !) The syncdoubler II detects automatic the screen mode and doubles the sync if Hires and put the amiga sync through if no Hires. Because the c1 clock is devided through 4 in the PIC and this is no Because the c1 clock is devided by 4 in the PIC and this is no integer multiple from the horizontal frequency I had to use a special synchronisation between the PIC and the amiga, this is done by the NAND. Have a look on the source. The source is written for the 16C84, you can assemble, simulate, emulate and program it with our Amiga PIC tools available on my Homepage: http://linux.rz.fh-hannover.de/~duesterb or on AmiNet: search for APIC. The syncdoubler is not a scandoubler ! a scandoubler buffers the video in a special RAM, the syncdoubler doubles only the syncs ! If you could not imagine how the result looks like have a look on the three screenshots from my monitor made with a video camera. Good luck, Dirk ---niks naks, oujee--- Tuo http-osoite ei näköjään ei toiminut...