New GR8BIT video board

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Door Eugeny_Brychkov

Paragon (1107)

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12-11-2019, 21:34

The development took about 6 months - I had to search for information and make tough decisions (search for my posts on SE.EE and AD EngineerZone). I have learned a lot designing it, and very proud it worked properly at the first start. The board can contain either V9938 or V9958, has RGB, S-video and color composite outputs. It can detect frequency of the VDP and switch to respective PAL or NTSC mode on its composite output.

With V9958:

With V9938:

80-character mode over composite: not perfect, but characters can be easily recognized. Interesting, that image in PAL mode is better than in NTSC mode.

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Van sdsnatcher73

Paladin (667)

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12-11-2019, 22:26

Wow Eugeny! Cool stuff.

Van OeiOeiVogeltje

Paragon (1310)

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12-11-2019, 22:49

Hello Eugeny
its probably a magical device coming from you but....silly question of course....
what does it do?
and does it fit in a Gr8bit?

Van Eugeny_Brychkov

Paragon (1107)

afbeelding van Eugeny_Brychkov

12-11-2019, 22:55

OeiOeiVogeltje wrote:

what does it do?
and does it fit in a Gr8bit?

Smile

It is for GR8BIT.
And It is a video board.

Thus it does show image on the screen, and it fits into GR8BIT. It is based on the original video board in its digital part, but has analog part totally rebuilt.

Van Edevaldo

Master (134)

afbeelding van Edevaldo

13-11-2019, 00:51

Fantastic design, Eugeny. Congrats.

Very complex PCB. What is the size smd passives on the board? 0603? 0402? They look tiny.
What are the 3 dip chips above the SRAMs? Are you latching the addresses so they look like dynamic rams? I can't recognize the chips.

Van Eugeny_Brychkov

Paragon (1107)

afbeelding van Eugeny_Brychkov

13-11-2019, 00:50

0805. Yes, those are registers latching address. Without them video modes 7 and up are not properly displayed.

Van Manuel

Ascended (15842)

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13-11-2019, 09:02

Strange, for some reason these photos only show up on my phone...

Van Eugeny_Brychkov

Paragon (1107)

afbeelding van Eugeny_Brychkov

13-11-2019, 15:29

Manuel wrote:

Strange, for some reason these photos only show up on my phone...

For me show well in Chrome. But yesterday, when posting to Twitter, photos did not show in the browser at all. Something rong is going on with IT. Time to unpack our MSXes and install SymbOS onto them, as they always perform excellently. Well, almost always Smile

Van Edevaldo

Master (134)

afbeelding van Edevaldo

13-11-2019, 17:02

The images showed correctly to me yesterday and today. Yesterday a couple of them were linking to facebook... But not today.

Van bigral

Supporter (7)

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13-11-2019, 17:53

Why to use cache sram developed circa 1992 instead of dram from 1980? This VDP was not supposed to use it. Also why such complexity and smd components, all of this would have much cooler look with old retro style components.

Van Eugeny_Brychkov

Paragon (1107)

afbeelding van Eugeny_Brychkov

13-11-2019, 18:11

bigral wrote:

Why to use cache sram developed circa 1992 instead of dram from 1980? This VDP was not supposed to use it. Also why such complexity and smd components, all of this would have much cooler look with old retro style components.

Like this one? It's already there.

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