Author Topic: Everdrive GB X- last few banks in 8MB space always corrupted?  (Read 626 times)

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Offline JavierBlitse

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Before I made this post, I made sure to look at the firmware update history to see if this problem was patched out. Unfortunately, it hasn't, but makes sense seeing that it only shows up in a specific use case.
I've been extensively testing an audio encoder I made for the Gameboy and Gameboy Color using an EDGB X3, and for most audio ROMs it works. Where it starts to have problems is with tracks that are only a few banks away from overflowing the entire 8MB ROM space.
When the audio is a few seconds away from ending, it first gets cut off completely for a second (presumably all zeroes,) returns for another second, followed by a few seconds of ear-piercing glitchy distorted garbage. This garbage audio is slightly different every time the problem happens, so some of the data must be getting written there.
I wouldn't be surprised if it was intentional, because no commercial game (and most homebrews/demos) don't take up this much ROM space, and therefore the OS could use it for something.
Any chance it'll get patched out in the future?

Offline nuu

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #1 on: April 01, 2021, 09:55 AM »
Since the Everdrive is advertised as having 8MB ROM space, it must be a bug. On the other hand the original ED64 was initially advertised as having 64MB ROM space although the top part of it was actually used as the save memory space (unless the game used EEPROM for saving).

Offline lee4

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #2 on: April 02, 2021, 01:15 AM »
All Everdrive X3 models have memory shared rom+save+os this why x3 required to reset to save save file

All Everdrive X7 models have dedicated memory.for rom, save and os
ED64 v2.0, 3.0 & X7 | EDMD v3 | MEGAED X7 M15 v2.01 & PRO rev B | TED v2.4 | EDN8 v1.2N & Pro M19 N1 | SED v2.1 | SD2SNES rev E1 & PRO rev.B | EDGB v1.1 & X7 M17 rev B | EDGBA X5 M16 rev A & Mini M19 Rev B
RetroUSB AVS | Super NT | Mega SG | Super Retro Advance |  16bitPocket GBC | PCE+SSD3

Offline nuu

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #3 on: April 02, 2021, 11:02 AM »
Ok, it does say max ROM size 8MB, and not 8MB dedicated ROM space. So it's 8MB total RAM and up to 128kB of it can be used for saving.

I think that should be made clear in the description on the homepage.

Offline Marteicos

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #4 on: April 02, 2021, 04:48 PM »
On X3 page at some point said it lacks dedicated sram chip so a part of the 8MB is used to simulate the save system.

Interesting, know we know what happens with the X3 when a rom too big is loaded.

The X5 or X7 is best suited for the usage OP wants to employ to the cart.

Offline nuu

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #5 on: April 03, 2021, 11:29 AM »
The homepage doesn't mention this now.

Offline JavierBlitse

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Everdrive GB X3 cannot make use of "Max 8MB ROM"
« Reply #6 on: April 04, 2021, 04:17 AM »
Ok, it does say max ROM size 8MB, and not 8MB dedicated ROM space. So it's 8MB total RAM and up to 128kB of it can be used for saving.

I think that should be made clear in the description on the homepage.

I actually looked at the homepage, and compared all of the models, and this is what I came up with (according to Krikzz' language):
-X3 has no battery to back up SRAM, and cannot do save states, does not have in game menu and does not have RTC
-X5 has battery to back up SRAM, but no save states, in game menu or RTC
-X7 has battery to back up SRAM, save states, in game menu and RTC

To be specific, the markings on the back of my X3 say "EverDrive-GB X7 Model 17, Rev.B 26.08.2017", and there are unpopulated spots on the PCB for a battery and an RTC chip, as well as an unpopulated spot where the SRAM chip would go... it doesn't mention it doesn't have support for 8MB ROM AND 128K SRAM, but it doesn't say it doesn't have it either.  :(
Also, "Max 8MB ROM" should be synonymous with 8MB of dedicated ROM space provided you don't need any extra RAM. And in my use case, the audio player, it does not use any extra RAM, so the 8MB should be usable for just the ROM right? Apparently not.  :( If the newer X3 models address this issue, I'll let this pass because I bought mine around 3 years ago, but if not, then I feel that X3 users are getting ripped off and we should do something about it.

Offline nuu

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Re: Everdrive GB X- last few banks in 8MB space always corrupted?
« Reply #7 on: April 04, 2021, 09:09 AM »
You didn't use any SRAM and you still don't have 8MB available for ROM?

Yes, I too think it should clearly say how much total memory and how much is available for what. It clearly says that the only difference from X5 is that doesn't have a battery which isn't true if it is like lee4 says.