How does EZ Flash Junior work?

[Czo]

I previously thought, when I start a game, the device loads the ROM file from the SD card to the onboard flash memory (S71GL ic). But, according to the markings on mine, it's maybe not. Because I reckon the flash is in the U4 71GL032A40BFW0F, which is only 32 Mbits, not 64, but I can load a 64 Mbit ROM without any hassle.

I attached a photo of my card and a macro shot from the top-left BGA chip.

Anyone know what the purpose of the top-left chip (U9) is? I cannot find a datasheet for it (3350LLZDQ0 or 3350LLZDQO and maybe created by Intel?). Some sites describe it as SRAM, but the 71GL (U4) also contains 4MBit PSRAM.

The board also contains a second (and smaller) flash chip (U2 P25D40SH; right to the FPGA), which may contain the initial system and maybe the settings variable for auto-save tickle on the settings page.

The U3 8563S (up from the sd slot) will be the RTC, and the two bottom chips (U6 and U7, 74LVT162245) will be the bus driver.

The U1 is a voltage regulator.

So, my question is, how can I load a 64 Mbit ROM file, or how does this thing actually work?

 

[moon_rabbit]

It uses PSRAM or SRAM present in the S71 chip.
Marked 064 and 032 are mixed and used interchangeably, and there is no noticeable difference even if they are swapped.
ROM is loaded from a chip presumed to be an Intel chip.
Although the exact details are difficult to determine due to the lack of a datasheet, the Intel chip is likely an MCP chip configured with PSRAM and NOR flash.

 

[master801]

The "Intel" IC is 128Mb with 64Mb of PSRAM.

This is the datasheet: https://partstack.com/d/micron-technology/rd38f3350llzdq0/110478375

Kindly found from here: https://www.vyrian.com/p/micron-technology/rd38f3350llzdq0/110478375

Vyrian says Micron, the IC's silkscreen says Intel, and the datasheet says Numonyx, but this is the correct datasheet.

Intel made Numonyx, Micron bought Numonyx. Confused yet?

 

[Czo]

Thanks for the datasheet! So, both the Intel/Micron/Numonyx (Intel bought Micron's flash storage department maybe a decade ago, if I remember correctly) and the S71 IC contain flash memory and (p)SRAM.

On my configuration, the S71 contains 4 Mbits of PSRAM ("40" in the part number), but I saw lots of photos from cards with 4 MBits of REAL SRAM ("04") or even 8 Mbits (both SRAM "08" and PSRAM "80"), and lots of other photos where the flash size was 64 Mbits ("64" in the part number) instead of 32 Mbits. And the Intel IC on mine contains 2x128 Mbits FLASH and 64 MBits of PSRAM.

So, maybe, the game code was running from the Intel IC, even maybe, from the PSRAM (that's why it can load the ROM faster than the Chinese EverDrive clones?), and maybe the S71 IC is used for the in-game Flash and SRAM "emulation"? In this case, there is no significance about the size of the S71's internal components.

I just try to understand how it works, because lots of people complain about energy usage (EZ Flash vs real EverDrive), and by my measurements, this EZ Flash Jr only requires ~0.1W more power than the original game cart (measured on my DC PSU where the game (Donkey Kong Country GBC version) was on the language select screen. I already ordered some components to modify this PSU to report the continuous measurements over USB to easily generate a graph), but my backlight LCD will increase consumption by between 0.25W and 0.5W depending on the brightness level, and I really don't want to kill my GBC (this is my first ever game console in my life! ). The base level with original screen and game cart was only 0.18W. So, EZ Flash adds an extra half, but a backlight screen can even triple the original consumption.

 

[Jayro]

Thanks for the datasheet! So, both the Intel/Micron/Numonyx (Intel bought Micron's flash storage department maybe a decade ago, if I remember correctly) and the S71 IC contain flash memory and (p)SRAM.

On my configuration, the S71 contains 4 Mbits of PSRAM ("40" in the part number), but I saw lots of photos from cards with 4 MBits of REAL SRAM ("04") or even 8 Mbits (both SRAM "08" and PSRAM "80"), and lots of other photos where the flash size was 64 Mbits ("64" in the part number) instead of 32 Mbits. And the Intel IC on mine contains 2x128 Mbits FLASH and 64 MBits of PSRAM.

So, maybe, the game code was running from the Intel IC, even maybe, from the PSRAM (that's why it can load the ROM faster than the Chinese EverDrive clones?), and maybe the S71 IC is used for the in-game Flash and SRAM "emulation"? In this case, there is no significance about the size of the S71's internal components.

I just try to understand how it works, because lots of people complain about energy usage (EZ Flash vs real EverDrive), and by my measurements, this EZ Flash Jr only requires ~0.1W more power than the original game cart (measured on my DC PSU where the game (Donkey Kong Country GBC version) was on the language select screen. I already ordered some components to modify this PSU to report the continuous measurements over USB to easily generate a graph), but my backlight LCD will increase consumption by between 0.25W and 0.5W depending on the brightness level, and I really don't want to kill my GBC (this is my first ever game console in my life! ). The base level with original screen and game cart was only 0.18W. So, EZ Flash adds an extra half, but a backlight screen can even triple the original consumption.

It's mostly the ROM loading that usus all the power, it can become unstable with a stock power regulator if you're using batteries and a backlit screen. I've found that LiPo cell with the backlight turned all the way down can get around this instability, and when the ROM is fully loaded and booted, the brightness can be turned back up. It's just silly to have to do all that crap. I gave away my Jr cart and bought an EDGB from AliExpress for half the price, and I'm much happier with it.

 

[Czo]

It's mostly the ROM loading that usus all the power, it can become unstable with a stock power regulator if you're using batteries and a backlit screen. I've found that LiPo cell with the backlight turned all the way down can get around this instability, and when the ROM is fully loaded and booted, the brightness can be turned back up. It's just silly to have to do all that crap. I gave away my Jr cart and bought an EDGB from AliExpress for half the price, and I'm much happier with it.

Hm, it's strange. I never had any problems in the past month (I've got this circa three weeks ago; tried nearly 100 games), and according to my PSU's display, loading a game is not as power-demanding as running it (*). But if I got the I2C current/voltage meter things, I will check it again and come back with some graphs. Ps. I only have this EZ-Flash card.

(*) The EZ-Flash firmware history for 1.05 reports some "turbo loading speed" thing. Maybe the previous version copied the content of the ROM to Intel's chip flash storage, and the 1.05 version loads it to the SRAM? That was (or will be, because this is still in beta) a huge decrease in loading speeds and power consumption too.

I hate that there is zero documentation available for these things (for the flash carts and the LCD/OLED displays etc).

Edit: I am on FW5/K1.05e

 

[Jayro]

Hm, it's strange. I never had any problems in the past month (I've got this circa three weeks ago; tried nearly 100 games), and according to my PSU's display, loading a game is not as power-demanding as running it (*). But if I got the I2C current/voltage meter things, I will check it again and come back with some graphs. Ps. I only have this EZ-Flash card.

(*) The EZ-Flash firmware history for 1.05 reports some "turbo loading speed" thing. Maybe the previous version copied the content of the ROM to Intel's chip flash storage, and the 1.05 version loads it to the SRAM? That was (or will be, because this is still in beta) a huge decrease in loading speeds and power consumption too.

I hate that there is zero documentation available for these things (for the flash carts and the LCD/OLED displays etc).

Edit: I am on FW5/K1.05e

Mine was on 1.04 back when I still had it, so the changes in 1.05 may have changed things, I'm unsure.

 

[Czo]

I've finished with the modding of my lab PSU, so I can now measure power usage with a PC. Here are the comparisons between the original Donkey Kong Country game cartridge versus the EZ-FLASH Junior when EZ-FLASH loads the game with the "start then A" combo. I tried to synchronise the charts as I could; to make better measurements, I need to figure out how to do this better.

The ROM cartridge has only one chime, and the EZ-FLASH has a big spike with nearly 1.1W usage when loading the ROM. My GBC has a Hispeedido 2.45 drop-in screen, and the brightness value was 8 from 15.

Anyone tried to downgrade an EZ-FLASH Junior, especially FW5 to FW4? In the future, I would like to do some more tests, with multiple brightness levels and with the OEM screen as well.

Edit: The firmware can be downgraded with the updater package, so I made a second graph, where the FW4 chart has been added. Loading a ROM with FW4 is even slower, and even more spikes are visible there. Overall, the power consumption in FW4 is higher than in FW5 when a ROM file is loading. The consumption when the game is running is nearly the same (below the error threshold).