Glitches using "advanced" carts on modded FB2

[vitoco]

Hi! I always wanted to mod a Flashback 2 console, but I couldn't get one locally, 'till now! But the console was already modded with a cartridge port, so I missed the fun.

 

Anyway, I went directly to the second step: try the PlusCart and the Harmony carts on this console. Both worked, but not very well. Both of them have glitches that corrupt the menu display. ROMs can still be selected and they load as expected, but a couple of the ROMs I tried also got display glitches.

 

Might it be just me or is this common for modded FB2?

 

Thanks!

 

[+Andrew Davie]

On 8/20/2021 at 9:44 AM, vitoco said:

Hi! I always wanted to mod a Flashback 2 console, but I couldn't get one locally, 'till now! But the console was already modded with a cartridge port, so I missed the fun.

 

Anyway, I went directly to the second step: try the PlusCart and the Harmony carts on this console. Both worked, but not very well. Both of them have glitches that corrupt the menu display. ROMs can still be selected and they load as expected, but a couple of the ROMs I tried also got display glitches.

 

Might it be just me or is this common for modded FB2?

 

Thanks!

 

 

The menu displays use very precise timing and knowledge about how a real '2600 TIA chip actually works.

If the FB2 is not emulating the TIA chip almost exactly, then this is the source of the display glitches/corruption.

In other words, nearly certainly a FB2 fault, in my opinion.

 

 

[vitoco]

22 hours ago, Andrew Davie said:

 

The menu displays use very precise timing and knowledge about how a real '2600 TIA chip actually works.

If the FB2 is not emulating the TIA chip almost exactly, then this is the source of the display glitches/corruption.

In other words, nearly certainly a FB2 fault, in my opinion.

 

 

I agree with you. I just thought that the fact of soldering some components during the mod could introduce such corruption, just like it has been observed in some 2600 consoles when modding for A/V.

 

In other words, my project to have a FB2 with the PlusCart/UnoCart went to trash...

 

For the curious, this is how it looks like:

 

 

[+MrZarniwoop]

6 hours ago, vitoco said:

For the curious, this is how it looks like

I can report the same on my FB2.

[+Al_Nafuur]

On 8/20/2021 at 1:44 AM, vitoco said:

 ROMs can still be selected and they load as expected, but a couple of the ROMs I tried also got display glitches.

 

Are the glitches in the ROMs the same in PlusCart/UnoCart and Harmony?

 

If you have the original cartridge to one of the glitchy ROMs, it would be interesting to see if it glitches too.

[vitoco]

2 hours ago, Al_Nafuur said:

Are the glitches in the ROMs the same in PlusCart/UnoCart and Harmony?

I don't have the UnoCart, but I'm preparing for the common firmware with both WiFi and SD.

 

The Harmony looks like it's dropping frames in its menu, no flickering fonts, it just displays a still image:

 

 

In that SD I had the fonts demos for the PlusCart default set poll, and Glacier Belle looked like this:

 

 

 

2 hours ago, Al_Nafuur said:

If you have the original cartridge to one of the glitchy ROMs, it would be interesting to see if it glitches too.

The glitch I saw it was in at least one of the FB2 included ROMs: Yar's Return. I tried it through the PlusCart in the 7800 and it's still glitchy, so I got the original version of the game, checked here: 

I don't have any AA store physical games (DPC+ or Melody) to check for other timming issues.

 

I tried PitKat from both the Harmony and the PlusCart, and I always got a black screen.

 

Robot City from the PlusCart displays a corrupted maze, and it is unresponsive (I could't play it):

 

 

BBlocks is playable, the fake 0 in the score looks OK, but the grid has irregular horizontal spacing:

 

 

Something else to try? ?

 

[+-^CrossBow^-]

Robot City uses the difficulty switches or black n white switch to enable a pause mode. My guess on why it isn't responding is because the default selection of the FB2 puts the game into paused mode when turning on the system. But it wouldn't correct for the odd screen mazes. What does Kool-Aid Man do when you try and load it up?

 

 

[vitoco]

30 minutes ago, -^CrossBow^- said:

Robot City uses the difficulty switches or black n white switch to enable a pause mode. My guess on why it isn't responding is because the default selection of the FB2 puts the game into paused mode when turning on the system. But it wouldn't correct for the odd screen mazes.

I could start the game by pressing difficulty switches a couple of times. But more glitches appeared: only one side of the hellicopter's bitmap is used when moving horizontally, and all the tanks froze after some seconds. Also, the lower side borders jitter a little while moving to some directions.

 

 

33 minutes ago, -^CrossBow^- said:

What does Kool-Aid Man do when you try and load it up?

I tried the fixed version from the PlusCart and it seems to do the same things I saw in a YouTube video of the game. The original (I guess) version failed in both the FB2 and the 7800 consoles.

 

[+MarcoJ]

IIRC, the FB2 has a problem with store instructions into the cart space in certain address ranges. However, it can play just about all the original atari carts if I remember right.