What is a "Bit" anyways - an excerpt from the Atari Jaguar Story

Hi I wanted to introduce myself, my name is Andy and I have many interests that I always wanted to blog about and I just got an opportunity to do so on this network. I am a programmer by profession and love tinkering with electronics. One of my hobbies is retro game collecting and I love to buy broken electronics and fix them. In the future I will write about technology, including new and old computers, and videogame systems, programming, classic/modern gaming in general and maybe some sports sprinkled in every now and again. My hope in creating this blog is to foster some thoughtful discussion within the community. Hopefully you guys will like my content and provide me with feedback for future content.

Today let’s start with talking about the Atari Jaguar released in 1993. There is much talk in the retro gaming community as to whether it is a 64-bit machine or not. Instead of talking about how games look and trying to judge by those standards, let’s look at the actual tech, after all just because you buy SteamWorld Dig on your pc doesn’t make it a 16-bit machine.

What is a bit?
First let's discuss what a “bit” is. It is the amount of data that the CPU can process at a time 8-bit means that data bus is 8-bit meaning 8-bit of data at a time. Think of a highway the wider the highway (data bus) the more cars (instructions) can fit at a time. Let’s take the Super Nintendo for example, it is a 16-bit machine does this mean that it is 2x more powerful than the 8-bit Nintendo? No. Let’s compare

A CPU contains registers where the work is done. In truly simple terms, a 16-bit CPU will contain 16-bit registers and an 8-bit CPU will contain 8-bit registers so this means that 16-bit CPU can do twice the amount per cycle with all other things equal (which rarely is the case). However, if you had an 8-bit processor with 4 registers and a 16-bit processor with 2 registers the same “work” can be done per cycle. Consider things aren’t this simple as 8-bit CPUs can have 16-bit registers. Head hurt yet? Again, this is an oversimplification. Feel free to ask more technical questions in the comments section and we can dig deeper.

Is the Atari Jaguar 64-bits?
Let’s go back to the original question. This won’t be straight forward kids but let’s look at this specs. The Jaguar contains 5 processors, they are:

1. Control processor 16/32-bit Motorola 68000 running @ 13.295 (similar to the Genesis processor albeit running almost at twice the speed)
2. DSP 32-bit Sound chip
3. 32-bit GPU that has direct access to the system bus (capable of reading 64 bits)
4. 64-bit Object processor (used mainly for moving sprites)
5. 64-bit Blitter with 64-bit register (remember the example from above?)

Consider this, if the Jag had one processor, the Object processor or the Blitter it would be no doubt a 64-bit machine. So why do people think that the Jaguar was a 32-bit box. It could be because of the Motorola 68K or the 32-bit GPU chip, but the biggest culprit that I have heard is that the games don’t “look” 64-bit. So that begs the question, what are 64-bit games supposed to look like. Most would point to the unfair comparison of the Nintendo 64. Why is this unfair? Because the N64 came out in 1996 a whole 3 years after the Jaguar, which is half of a generation! Additionally, it was not the 64-bitness that is the reason that the N64 bests the Jaguar. It was the larger carts faster processor and more memory that can be attributed to. Lastly there were no true 64-bit games for Nintendo 64, but that’s a blog for another day. Now if Nintendo 64 is not the measure stick what is?

The truth is a bit doesn’t have a “look”. When gamers talk about the 8-bit look they are likely referring to is what they grew up playing, the younger U.S gamer will think the NES, older gamers Atari 2600, EU gamers will think ZX Spectrum they are all right, but all three answers have distinct looks.

So if the Jaguar is 64 bit why do the games not “look” like 64 bit games

There are many reasons. The top reason is the Motorola 68000 and its popularity. Everyone new how to code for it since it was the main processor for both the Amiga and Sega Genesis. The combination of that and Atari didn’t provide proper devkits resulted in many games that were better colored versions of Genesis games like Pitfall, Bubsy, Dragon: The Bruce Lee Story, Raiden and Zool. Another issue is that cartridge size was typically no larger than 2MB with some exceptions. So games couldn’t see their true potential.
There were games that were definitely next gen. The best version of Wolfenstein 3D and Doom were on this box. A great version of NBA Jam TE. Rayman, Tempest 2000, and Alien vs Predator were great Jaguar exclusives. At the end of the day the bits of a machine don’t matter (we don’t even talk bits anymore with videogames) all that matters is that you are having fun.