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The 7800GD (New 7800 Flash Cartridge?)


SainT

Do you really want one?  

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  1. 1. Would you be interested in buying a 7800 SD cart (expected price around £60-£70)?

    • Yes
      159
    • No
      7

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Is there any chance of an option to force NTSC colour pallet when using the RGB out on pal games, there are instances (Bentley bear crystal quest) for one that on NTSC machines the ‘bear’ is brown, on PAL machines, he is green and looks like a recycling wheelybin!

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10 hours ago, omf said:

Is there any chance of an option to force NTSC colour pallet when using the RGB out on pal games, there are instances (Bentley bear crystal quest) for one that on NTSC machines the ‘bear’ is brown, on PAL machines, he is green and looks like a recycling wheelybin!

Yes, that’s perfectly possible. I wasn’t aware some games forgot to change the colours for PAL!

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8 hours ago, Shawn said:

 

So I could take the video from the console and not have to use the on cart video correct? 

Of course, it’s just a cartridge. It doesn’t affect the way the console works, it just expands it’s capabilities.

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In Crystal Quest I actually *did* change the colors for PAL; although it looks like I may have chosen the wrong colors to map to. 

 

Back then, I used to use 'sed' to remove the ';NTSC' and ';PAL' comment headers in the code below depending on what I was building.  (Now I just auto-detect and use a routine to add $10 to the color, with some exceptions):

 

Quote

;  COLOR DEFINITIONS
;NTSC BLACK      =     $00
;NTSC DKGREY     =     $04
;NTSC GREY       =     $08
;NTSC LTGREY     =     $0C
;NTSC WHITE      =     $0F

;NTSC YELLOW     =     $1C
;NTSC GOLD       =     $2C
;NTSC ORANGE     =     $3C

;NTSC DKDKRED    =     $30
;NTSC DKRED      =     $34
;NTSC RED        =     $38
;NTSC LTRED      =     $3C

;NTSC DKDKPINK   =     $50
;NTSC DKPINK     =     $54
;NTSC PINK       =     $58
;NTSC LTPINK     =     $5C

;NTSC DKDKPURPLE =     $60
;NTSC DKPURPLE   =     $64
;NTSC PURPLE     =     $68
;NTSC LTPURPLE   =     $6C

;NTSC DKDKBLUE   =     $80
;NTSC DKBLUE     =     $84
;NTSC BLUE       =     $88
;NTSC LTBLUE     =     $8C

;NTSC TEAL       =     $A8

;NTSC DKDKAQUA   =     $A0
;NTSC DKAQUA     =     $A4
;NTSC AQUA       =     $A8
;NTSC LTAQUA     =     $AC

;NTSC DKDKGREEN  =     $C0
;NTSC DKGREEN    =     $C4
;NTSC GREEN      =     $C8
;NTSC LTGREEN    =     $CC

;NTSC DKDKBROWN  =     $F6;$F0
;NTSC DKBROWN    =     $F9;$F4
;NTSC BROWN      =     $FC;$F8
;NTSC LTBROWN    =     $FF;$FC 


;PAL  BLACK      =     $00
;PAL  LTPINK     =     $5E
;PAL  WHITE      =     $0E
;PAL  PINK       =     $57
;PAL  GREEN      =     $D4
;PAL  PURPLE     =     $63
;PAL  DKPURPLE   =     $60
;PAL  BLUE       =     $96
;PAL  YELLOW     =     $2E
;PAL  LTBLUE     =     $AE
;PAL  DKBLUE     =     $82
;PAL  BROWN      =     $26
;PAL  LTGREEN    =     $DC
;PAL  LTBROWN    =     $24
;PAL  GOLD       =     $2A
;PAL  HOTPINK    =     $54
;PAL  ORANGE     =     $3A
;PAL  AQUA       =     $BB
;PAL  DKDKRED    =     $40
;PAL  DKRED      =     $44
;PAL  RED        =     $48
;PAL  LTRED      =     $4C
;PAL  DKGREEN    =     $D2
;PAL  DKDKGREEN  =     $D0
;PAL  DKBROWN    =     $22
;PAL  DKDKBROWN  =     $20
;PAL  GREY       =     $06
;PAL  TEAL       =     $A8
;PAL  LTPURPLE   =     $6A
;PAL  LTAQUA     =     $BF
;PAL  LTGREY     =     $0C
;PAL  DKDKBLUE   =     $80
;PAL  DKAQUA     =     $B4

 

Edited by PacManPlus
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1 hour ago, x=usr(1536) said:

As I understand it, the cartridge's video output is RGB-only.  Is there any possibility of it eventually supporting S-Video and / or composite?

Nope, RGB only I’m afraid! You can get RGB to composite converters for a better composite image than the 7800 will natively provide, I would expect. 

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7 hours ago, SainT said:

Of course, it’s just a cartridge. It doesn’t affect the way the console works, it just expands it’s capabilities.

 

Fantastic! :) I greatly prefer this as I've come across a couple carts that you had to take the video from the cartridge based to how it was designed. Knowing your cart is able to use the consoles video out on it's own is very reassuring. Thanks for clarifying that for me.

 

EDIT: It really looks like your 7800 cart is going to be the best option to date and will surpass all other offerings. I can't wait for it.

Edited by Shawn
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On 1/14/2023 at 8:30 AM, PacManPlus said:

In Crystal Quest I actually *did* change the colors for PAL; although it looks like I may have chosen the wrong colors to map to. 

 

Back then, I used to use 'sed' to remove the ';NTSC' and ';PAL' comment headers in the code below depending on what I was building.  (Now I just auto-detect and use a routine to add $10 to the color, with some exceptions)

On 1/13/2023 at 4:07 PM, omf said:

Is there any chance of an option to force NTSC colour pallet when using the RGB out on pal games, there are instances (Bentley bear crystal quest) for one that on NTSC machines the ‘bear’ is brown, on PAL machines, he is green and looks like a recycling wheelybin!

On 1/14/2023 at 2:53 AM, SainT said:

Yes, that’s perfectly possible. I wasn’t aware some games forgot to change the colours for PAL!

It's important to keep in mind, back when Bentley Bear was under development and released (2011-2013), as well as other homebrew games during that time period and earlier, the ProSystem emulator was the standard, including its default one shared color palette between both NTSC and PAL regions. 

 

The more recent PAL colors emulator accuracy (shown below), availability and overall understandings we have today as part of the testbed, is something that was not readily available for reference back then:

image.thumb.png.1fe69d54b3cd35f2049ce1033c5c4595.png

image.thumb.png.cab900c45167cf5cc6123ea38bc1c8e9.png

Hindsight is 20/20. 

 

Clearly, Bob's listed current selection method would have made for better colors then. 

 

For example, PAL $23 and $28, or of similar PAL $2x range, nowadays, would be leveraged for the 'brown' selections of Bentley, instead of PAL $13 and $18 that was used back then.

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4 hours ago, Stephen said:

How is it possible to generate RGB via the cart port?

FPGA implementation of the MARIA chip that runs in tandem with the console. 

Ditto for the TIA, which allows the 2600 mode to also have RGB out.

MARIA implementation is SainT's own.

TIA implementation is leveraged from MiSTer FPGA.

 

image.png.b13b26736a3ca820566257ce780c64b4.png

 

To be clear, leveraging the RGB output of the 7800GD is completely optional. 

It can be used strictly for its flash/multi-cart ROM support features and just stick to the original RF or whatever console mod is already in place on the respective 7800.

There is no interference, conflict, or compatibility issue.

 

image.png.00434d848dadf0fcd4064090d7cd4204.png

 

Genesis/MegaDrive 2 RGB cables can be leveraged for the 7800GD RGB video output such as Composite or SCART.  There are even HDMI cables and adapters available.  Works great with the RetroTINK-5x too.

 

The optional Mega7800 MegaDrive pad adapter will allow users to press the Start button on a Sega Genesis controller to bring up the 7800GD in-game menu screen.*

 

*EDIT:  To add, the state save and reload feature.  For all games, real-time state save and load. 

 

Also, software volume control for all external audio chips (Includes support for Rikki & Vikki BupChip sound).  If using the video/audio output of the 7800GD, TIA audio level is adjustable, otherwise TIA volume is the default level of the console.

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Yep, what @Trebor said! A perfect recap.

 

With the TIA via FPGA I can help improve vsync stability a bit, but it will still be a little jittery. This is why I recommend an upscaler which has triple buffer capability (like tink 5xp) for maximum compatibility. If your TV is happy with hdmi jitter (my monitor doesn’t care at all), then you can simply use frame lock, but if it’s not (my bravia is unbelievably picky) then you’ll need to switch to triple buffer to get a picture. If you’re using a CRT, then it’s all good. CRTs just work. 😄

 

One thing worth mentioning is that the in-game menu allows state save and reload, which is a nice feature.

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1 minute ago, Muddyfunster said:

@SainT Sorry, I'm pretty sure that I've asked this, but I can't find the post anywhere.

 

Will I be able to link the GD7800 directly to my PC to transfer test builds, via USB? 

 

Thanks!

Not via USB, no, however there is a serial port on the side which can be connected to the PC via a USB<>RS232 type adapter.

 

I don’t have any support for uploading builds or debugging yet, but that is to come.

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