The relentless march of technology - combined with the rising price of certain retro games - has created a healthy market for flash carts which allow you to load up a bunch of ROMs onto an SD card and play them on your original vintage consoles.

We've made no secret of our affection for such carts in the past, despite the rather shady moral (not to mention legal) nature of ROM distribution, but if you've got the means to dump ROMs yourself then a flash cart is a valuable way of saving wear and tear on your collection - and it's more convenient than having to constantly dig games out of storage whenever you fancy playing them.

However, db Electronics has cast serious doubt over how suitable such carts are for your old systems, citing the mismatch between the 3.3V carts and the 5V systems they're being used on. The site states that many flash carts - and "multigame" carts, which chuck a load of games onto a single cartridge - don't have the correct tech in place to ensure that damage doesn't occur to both the cart itself and the console it's being used on:

When the console outputs 5V into a 3.3V input the extra voltage must go somewhere; 1st law of thermodynamics. It is converted to heat through the unintended conduction of clamping diodes, which can be harmful to integrated circuits. These diodes are there for protection against electrostatic discharge (ESD), which are very short and infrequent bursts of energy. They are not designed for continuous conduction and, therefore, continuous heat dissipation. Let’s take a look into why this occurs.

To understand what happens when a 5V signal is applied to a 3.3V input, we must first understand what a 3.3V input looks like. Typically, a digital input has 2 clamping diodes (D1 and D2 below) on its input to protect against small electrostatic discharges (ESD). When a logic high of 5V is applied to the circuit below, D1 starts conducting and essentially short circuits the additional voltage to the 3.3V supply. In certain flashcarts, including several Everdrive designs there is a small resistor (R1 – 100 ohms) to limit the short circuit current to approximately 12.5 mA between the 5V supply and 3.3V supply – this protection is inadequate since typical CMOS current ratings are ± 5.2mA.

On other common devices, such as multicarts, there is no R1 and a logic high of 5V driven directly into the 3.3V flash results in a short circuit between the 5V and 3.3V supplies. In either case, this causes unnecessary and potentially damaging stress on both ends:

+ On the console output since it is not designed to supply nearly 12.5mA (or more on multicarts) per pin
+ On the 3.3V Flash input since the clamping diodes D1 and D2 are not designed to dissipate large amounts of heat

The thing is, many of these flash carts are quite new and haven't been on the market long enough for us to see what kind of damage they can this cause to original hardware - even db Electronics admits that there's not sufficient data to really make a call on this definitively. But what could happen with flash carts which don't have the correct tech inside?

We hope you're sitting comfortably:

Prolonged use of components outside of their specified tolerances inevitably leads to failure. On the console side, the stress is excessive current output on digital outputs when driving a logic high. On the cartridge side, the stress is excessive heat dissipation due to conduction of the clamping diodes. I have already heard from several friends that their NES consoles have died most likely due to their admittedly heavy use of cheap multicarts. These are particularly bad. I would avoid these like the plague. I suspect poorly designed Everdrives will require more time before we start seeing failures.

If you want to get really technical, then db Electronics has also posted the following video which explains the issue:

db Electronics then goes on to rate a bunch of common flash carts - mostly Everdrives - and the verdict isn't great. The vast majority are listed as "avoid", with only the Mega Everdrive x5, Turbo Everdrive x2, Everdrive N8 and SD2SNES coming out with a high recommendation. Some carts - like Everdrives made for the N64 and Game Boy Advance - aren't listed as they run on 3.3V systems, so there's no mismatch. It is also pointed out that the more recent Everdrive carts have been engineered to a much better specification and moving forward, such voltage mismatches should become a thing of the past - which means the potential of future flash carts harming your consoles is removed completely.

What do you make of this stance? Do you own Everdrives, and will you stop using them now you've read this, or have you never seen the point of flash carts? Let us know by posting a comment.

[via db-electronics.ca]