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Why were cartridge sizes for the Super Nintendo always measured in megabit instead of megabyte?

Advertisement statements like "16 megs of awesomeness" etc., even though it actually just means 2 MB.

Isn't this totally nonsense and redundant?

I mean, it's not like a ROM can have additional bits that don't fill up a full byte.
So, unlike with internet speed, where data is actually downloaded in single bits, it makes absolutely no sense for ROM or RAM size. Every game always has a size of full bytes.

So, is this only some advertisement crap to make it sound more awesome?

In this case, why didn't they use kilobyte? It's a factor of 1000 instead of 8, i.e. even more awesome.
And at least it makes sense because while a game's megabit size will always be divisible through 8, the KB number doesn't need to fill up to complete megabytes.
"2000 KB of awesomeness" after NES games only had maybe 128 KB is at least a justified measurement.

Or is there actually a justified reason to measure ROM size in bits instead of bytes?

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Data transfer in telecommunications was measured in bits (BAUD, etc.) and I believe this predates the idea of 8-bit bytes. Early computers had different word sizes (e.g. 9-bit words), we didn't settle on 8/16/32 until later on.

EPROM/RAM IC sizes have always been specified in bits rather than bytes. They still are (check any electronics supply catalogue).

Even modern hard drives are kinda weird, using an alternate-universe kilobyte of 1000 bytes because it makes their advertised numbers bigger.

So... I mean, there's plenty of relevant precedent for using "megabits". "Megabytes" mainly became comfortable because of file systems on 8-bit and 16-bit computers.

The sizes of the ROMs present inside the cartridges being measured in megabits (as memory chips always had been) was enough to justify measuring the cartridges the same way, IMO.

A lot of people didn't even own computers during the early 90's, so it's not like the general public had any actual knowledge about megabits or megabytes. For most people, this information simply allowed games to be compared, they weren't able to comprehend how much information those numbers actually represented. The same way most people didn't know (and still don't!) what the terms "8-bit" and "16-bit" were referring to, they just knew that 16-bit was better.

Marketing departments like to use numbers, because anyone can compare numbers, even if they don't understand what the numbers mean in absolute terms. I don't think Nintendo, Sega, or anyone else expected consumers to know what "megabits" meant (obviously some people did), but they wanted to be able to imply that new games were better than old ones because they had "more megabits".

Except the end of the "Why Your Game Paks Never Forget" article in Nintendo Power was fairly clear that more megabits doesn't necessarily mean more fun. It gave the 256+256 kbit size of Dr. Mario as an example.

As you've seen, Game Paks are not all created equal. Some have special built-in features that allow greater variety in game design. But the measure of any great game is not memory size of whether it uses a MMC1 or MMC5. The real test is whether or not it's fun to play. Dr. Mario, a 256 K x 256 K game, requires less memory than many other new games. But once you start playing, it's almost impossible to stop. Remember, it's the stuff that memory is made of that counts.

Yeah. And this is always the case. In the modern day of this universe that nearly every household adopts a data connection (be it for computers, or for refrigerators!) and nearly everybody uses a mobile phone with a data plan the transfer speeds are always specified in bits. So, a 1M data plan actually means the transfer speed caps at around 1Mbit, and thus around 100kilo-bytes. Not only this is a standard but network providers capitalise this as a lucky marketing strategy, as many customers are not aware of this and still think they have a really fast connection.

Back in the old days of console gaming(before home computers became a necessary household item), though, there wasn't really any standardised way to measure the size of a game in a cartridge anything could be used. Still, Mbit was the most common (even to late cartridge based systems such as Neo Geo and Nintendo 64). This practice pretty much died when most systems moved to being disc based (still, it was flashier to say a CD could hold around 4000M of data, which was stated when the CD-ROM² of the PC Engine was released) and subsequently they started to use bytes in say HDD install, DLC and SD Card storage for consoles and handhelds (it would be silly to still use bits for the gigantic space requirements nowaways anyway).

There is a common exception to this in that web browsers may display download rates in bytes per second, to accommodate end users more familiar with file systems than telecommunications.

Well, apart from "accomodating users", it has the obvious advantage of actually making sense when the complete size of the file you are downloading is always measured in bytes.

Otherwise it would be like saying "We are driving 80 kilometers per hour towards our destination 35 miles away"

Yes, I was trying to sneak this in as an edit while you posted.


There was a standard for memory ICs, and that was bits, not bytes. Cartridge games were made from the same kind of memory devices, so that standard did apply. Developers would certainly have been familiar with EPROM sizes while working on their game. That was your target device, and it was always measured in bits. There was never any other standard for cartridges, as far as I know.

I kinda wonder what marketing for the FDS said of their disk capacity, though, since it actually had a byte-based file system, but was so closely aligned with a cartridge system. CD-ROM might be a grey area too with transfer speeds often specified in bits, but frequently used with bytey file systems as well.

Once you get to installing on a user's personal drive, where they are expected to manage storage and know their capcities in bytes, then there's not much reason to use anything else but bytes.

DRAM/SRAM chips on old computers often were only 1 or 4 bits wide, and the Intellivision system used cartridges that had 10-bit-wide ROMs.

So, yeah, the bit alignment was all over the place, continuing to the SNES era as well. Game magazines in all regions explained megabit and megabyte differences to readers in that era, so there wasn't ignorance about either term. The only illogical thing at this point was why some people would then still mistake "bit" for "byte" and come up with crazy values.

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Not every arm of a large company's messaging is going to be 100% on the same page 100% of the time; they can even be intentionally contradictory - Nintendo both wants to be seen as a company that puts fun ahead of cheap and as a cool, hi-tech company.

And for what it's worth, yes, it's gotta entirely be a marketing thing. After all, it's not like there was any other reason for consumers to know how big the ROM chips on their carts were (as evidenced by the fact that game companies don't advertise how much of a Blu-ray their PS4 games take up these days). Why bits instead of bytes? Probably the x8 advantage, and maybe because it let them avoid fractions for 4mbit or 24mbit games. Why not kilo-? Probably because the word "mega" sounds cool, at least to native English speakers, because it's long been used outside of technology for things that are massive and powerful. And as a guess, there's probably also a certain psychological law of diminishing returns on bigger numbers, where after a certain point they just start sounding like numbers and stop sounding "cooler" - I imagine that this sort of thing is focus grouped and market tested and such.

All very good points! Back when they started advertising the sizes of NES and Master System games, hardly any games reached the 1 megabyte mark (the Master System only got there because of brazilian exclusives, and the NES never did), and fractional numbers probably wouldn't sound as impressive. Plus, "megabits" was the standard way to measure the size of memory chips back then, so it simply made sense to use that to describe cartridges that used such chips.

On the Famicom, Metal Slader Glory is 8 Mbit. On the NES, Action 52 is 16 Mbit, and Action 53 vol. 3 will be 8 Mbit.

The real reason is so they could say things like "16 MEGA POWER!"

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Actually I was about to make my post longer, but after realising that it would become a wall of text and getting tired I ended up cutting it short (the fear of the frequent auto-log-out problem of the forums didn't help either, though I did press Ctrl-A Ctrl-C frequently when I typed). While it made sense to have only one way of displaying the size of a cartridge for most systems it was not the case with the Famicom, because of its (usual) CHR+PRG ROM configurations for the carts. Most magazines BITD showed game size in one single number, such as 1M(bit), 2M(bit), etc. However, certain magazine(s?) did write something like "1M + 512K", showing how its CHR and PRG ROMs were configured, and in case a cart contained RAM, be it CHR RAM, some additional work RAM or battery backed ones, they even went this far to write something like "1M + 512K + 64K SRAM", so there was no real standard to show how large a Famicom cart was. But of course they're all shown in bits, not bytes, so it's not contradictory to what you said. The difference in "standards" I mentioned was just whether they specifically showed the actual CHR-PRG ROM configuration, not whether it was shown in bits or bytes.

But! Actually I didn't know the CHR-PRG separation thing of the system BITD though. And since I was more familiar with how FDS stored stuff, having hacked game graphics on the real system and the like, and that pirarchived cart games for game copiers usually worked like 1 disk storing 1M of data, so a 2M cart game spanned 2 disks, so I was really confused on what things like 1M + 512K actually meant.

Megabits is not only for marketting (although I agree it definitely played a major role), but is also the standard size when buying RAM or ROM components. Because it's the only unit that can represent size regardless of data bus size. Counting bytes is fine, but it assumes 8-bit words, which is not always the case.