A3020 gaming

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mattdy4
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A3020 gaming

Post by mattdy4 » Thu Apr 26, 2018 10:41 am

When I try to run games on my NEC Multisync monitor I find that games are letterboxed vertically and only take up around 1/2 the screen. Is there anyway of running 4:3 full-screen?

I'm running the LCDGameModes module in mode 31 which is the only way I can play most games without the monitor syncing to a screenmode with "out of range" message. I have sync mode set to SVGA or Multisync (no difference).

Not sure if I need to use a monitor definition file or if I even can do that in RO3.11 - TIA

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danielj
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Re: A3020 gaming

Post by danielj » Fri Apr 27, 2018 7:49 am

If your monitor can't sync to the 15KHz modes, then unfortunately no :( - LCDGameModes improves the ratio somewhat, but it's not perfect.

If you get a BenQ BL912 monitor it can display all the A3020's modes perfectly :)

d.

sirbod
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Re: A3020 gaming

Post by sirbod » Sat Apr 28, 2018 7:58 am

EGA on VGA does a better job of correcting letterboxing, which is what ADFFS uses when run on a RiscPC.

Steve and I did have a long discussion around improving the timings back in 2016, whilst trying to improve Rockfall and fix GBA. There were several advantages from my perspective if we used EGA on VGA as the modes could be 75Hz, allowing ADFFS to get a perfect 50Hz on VIDC1 based machines. From my notes it looks like mode 15 was an issue as it required a 25MHz clock and was borderline, so that's where we left it.

In my last eMail to Steve, I had created a custom version of LCDGameModes that used EGA on VGA timings. Due to the mode 15 issue however, we didnt use it in LCDGameModes. In hindsight we should probably have added an option to allow you to switch between either full VGA compliance or EGA on VGA.

Essentially VGA compliance is using 640x480, EGA on VGA uses 640x350 so reduces letterboxing, but not all LCD support it and it pushes both VIDC1 and the RAM close to their limit in mode 15.

sirbod
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Re: A3020 gaming

Post by sirbod » Sat Apr 28, 2018 10:37 am

Attached is the EGA on VGA test version of LCDGameModes, it uses EGA on VGA for the usual game modes except 15, which is reliant on a VIDC Enhancer as I believe it was pushing the limit at 24Mhz.

The timings it's using are:

Code: Select all

;        BPP     HBPCH     HDISP    HFPCH  VBPCH    VDISP    VFPCH      SYNC    MODE
;           HSYNC    HLBDR     HRBDR   VSYNC   VTBDR    VBBDR     PIXRATE
 VIDC_List 0,  76,  63, 50,  640,  0,  10, 3, 19, 16, 256, 16,  88, 24000, 2  ; 0 IOC EGA on VGA
 VIDC_List 1,  76,  63, 50,  640,  0,  10, 3, 19, 16, 256, 16,  88, 24000, 2  ; 8 IOC EGA on VGA
 VIDC_List 2,  38,  44, 48,  320, 48,  10, 3, 19, 16, 256, 16, 109, 16000, 2  ; 9 IOC EGA on VGA
 VIDC_List 2,  76,  63, 50,  640,  0,  10, 3, 19, 16, 256, 16,  88, 24000, 2  ; 12 IOC EGA on VGA
 VIDC_List 3,  38,  44, 48,  320, 48,  10, 3, 19, 16, 256, 16, 109, 16000, 2  ; 13 IOC EGA on VGA
;VIDC_List 3,  76,  63, 50,  640,  0,  10, 3, 19, 16, 256, 16,  88, 24000, 2  ; 15 IOC EGA on VGA - issues
 VIDC_List 3,  76,  88, 64,  640,  0,  10, 3, 19, 16, 256, 16, 101, 25175, 2  ; 15 ..so using these timings instead
I don't believe there is an official EGA on VGA standard, so the timings were based on the details from this page.
Attachments
LCDgm031b_EGAonVGA.zip
EGA on VGA test version
(1.3 KiB) Downloaded 15 times

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