Jaguar 64 FAQ - Part 1
Created and maintained by Robert Jung

All you need to know about the Atari Jaguar and more... (not for the faint hearted! - Ed) MyAtari presents the first instalment of the Jaguar 64 FAQ by Robert Jung.
 

What was the Atari Jaguar/Jaguar64?

The Atari Jaguar was the world's first 64-bit home console video game system. Developed after three years of research, manufactured by IBM, the Jaguar was released in Fall 1993, and offered high-speed action, CD-quality sound, and polygon graphics processing beyond most other machines available at the time.

Originally released as the Jaguar, Atari had, at times, referred to the machine as the "Jaguar64" for marketing purposes. For the sake of simplicity in this document, the term "Jaguar" will be used.

What was included when you bought a Jaguar?

The Jaguar was first sold for $250. It came with the Jaguar itself, one controller, an AC adapter, a television RF switch box, and the CYBERMORPH video game. Later on, the Jaguar was sold without a game, and as time progressed, the Jaguar was sold for $150, then $99.

What happened to Atari, anyway?

The trials and tribulations of Atari could fill a small book (and, in fact, once did). To summarize VERY briefly, the history of Atari is as follows:

• 1972 Atari Inc. founded by Nolan Bushnell from a $250 investment.
  Pong arcade game becomes a smash sensation.
• 1976 Atari Inc. sold by Bushnell to Warner Inc. for $28 million.
• 1980 Atari Inc. posts record sales. $2 billion profits annually. Atari occupies 80 offices in Sunnyvale, CA.
• 1983 Decline of video games and irresponsible spending by Atari Inc. results in record losses ($536 million, up to $2 million daily).
• 1984 Warner divides Atari Inc. Home division (Atari Corp.) is sold to Jack Tramiel.
• 1985 Atari Corp. releases Atari ST home computer.
• 1989 Atari Corp. releases Atari Lynx, the world's first color hand-held video game system (see the Atari Lynx FAQ).
• 1993 Atari Games becomes Time-Warner Interactive.
• 1993 Atari Corp. releases Atari Jaguar, the world's first 64-bit home video game system.
• 1996 Time-Warner Interactive (Atari Games) sold to WMS.
• 1996 Atari Corp. announces reverse merger with JTS Corporation.
• 1996 Atari Corp. and JTS consummate deal on July 31 1996.
• 1998 Hasbro acquires the rights to Atari Corp.'s name and properties
• 1999 Hasbro releases their rights to the Jaguar to the public; Atari is reborn as their new home video game label.

What was IBM's role in the Jaguar?

IBM had a $500 million contract with Atari Corp. to assemble, test, package, and distribute Jaguar units. Manufacturing was done at IBM's Charlotte, NC facility, and the Jaguar was IBM's first attempt at producing a consumer-grade product for an outside vendor. By mid-1994, Jaguar units were also manufactured by Comptronix in Colorado Springs.

Jaguar circuit boards were manufactured and assembled by an IBM subcontractor; IBM then cased, tested, and packaged final Jaguar units, which were then sent to Atari. IBM had no participation in the actual design of the Jaguar chipset.

Okay, who did design the Jaguar?

The primary designers of the Jaguar were Martin Brennan and John Mathieson. They started their own company in 1986 called Flare 1, and designed an original multiprocessor game console. After the system was finished, Flare wanted to "evolve" the system, but needed funding for the job. Atari was contacted, believed in the idea, and agreed to participate. Atari, Brennan, and Mathieson started a new company called Flare 2 to develop the system. As Jaguar development moved along, it became apparent that the machine would leapfrog the then-new systems from Nintendo and Sega (the Super Nintendo and Sega Genesis, respectively), so they decided to bring the machine to light. The entire process took three years, from initial design to production-ready models.

The proprietary Jaguar chipsets were manufactured by Toshiba and Motorola. According to Chris Gibbs, Attention To Detail was asked to write technology demos for the Jaguar chipset. The company opted to develop a game instead, resulting in the first Jaguar title, CYBERMORPH.

The Flare design was reportedly based on a project called "Loki," developed by Sinclair Research. Information about the Loki project can be found at http://www.nvg.ntnu.no/sinclair/planet/lokifram.htm.

According to Jaguar developer Andrew Whittaker, "Some of that [Loki] technology also found a home in a machine called the SAM Coupe, which was manufactured and produced in the UK by MGT technologies (Bruce Gordon and Alan Miles, both ex-Sinclair staff also). It shared many interesting features with the Jaguar in terms of its video chip, but the machine sold very badly in Europe and the company folded."

What are the specifications of the Jaguar?

Physical dimensions:

• Size:
  9.5" x 10" x 2.5"
• Controls:
  Power on/off
• Display:
  Programmable screen resolution. Horizontal resolution is dependent on the amount of scanline buffer space given to the "Tom" graphics processor. Maximum vertical resolution varies according to the refresh rate (NTSC or PAL). Reportedly, a stock Jaguar (without additional memory) running NTSC can display up to 576 rows of pixels. 24-bit "True Color" display with 16,777,216 colors simultaneously (additional 8 bits of supplemental graphics data support possible) Multiple-resolution, multiple-color depth objects (monochrome, 2-bit, 4-bit, 8-bit, 16-bit, 24-bit) can be used simultaneously
• Ports:
  Cartridge slot/expansion port (32 bits) RF video output Video edge connector (video/audio output) (supports NTSC and PAL; provides S-Video, Composite, RGB outputs, accessible by optional add-on connector) Two controller ports Digital Signal Processor port (includes high-speed synchronous serial input/output)
• Controllers:
  Eight-directional joypad Size 6.25" x 5" x 1.6", cord 7 feet Three fire buttons (A, B, C) Pause and Option buttons 12-key keypad (accepts game-specific overlays)

The Jaguar has five processors which are contained in three chips. Two of the chips are proprietary designs, nicknamed "Tom" and "Jerry". The third chip is a standard Motorola 68000, and used as a coprocessor. Tom and Jerry are built using an 0.5 micron silicon process. With proper programming, all five processors can run in parallel.

"Tom"

• 750,000 transistors, 208 pins
• Graphics Processing Unit (processor #1)
  • 32-bit RISC architecture (32/64 processor)
    • 64 registers of 32 bits wide
    • Has access to all 64 bits of the system bus
    • Can read 64 bits of data in one instruction
  • Rated at 26.591 MIPS (million instructions per second)
  • Runs at 26.591 MHz
  • 4K bytes of zero wait-state internal SRAM
  • Performs a wide range of high-speed graphic effects
  • Programmable
• Object processor (processor #2)
  • 64-bit RISC architecture
  • 64-bit wide registers
  • Programmable processor that can act as a variety of different video architectures, such as a sprite engine, a pixel-mapped display, a character-mapped system, and others.
• Blitter (processor #3)
  • 64-bit RISC architecture
  • 64-bit wide registers
  • Performs high-speed logical operations
  • Hardware support for Z-buffering and Gouraud shading
• DRAM memory controller
  • 64 bits
  • Accesses the DRAM directly

"Jerry"

• 600,000 transistors, 144 pins
• Digital Signal Processor (processor #4)
  • 32 bits (32-bit registers)
  • Rated at 26.6 MIPS (million instructions per second)
  • Runs at 26.6 MHz
  • Same RISC core as the Graphics Processing Unit
    • Not limited to sound generation
  • 8K bytes of zero wait-state internal SRAM
  • CD-quality sound (16-bit stereo)
    • Number of sound channels limited by software
    • Two DACs (stereo) convert digital data to analog sound signals
  • Full stereo capabilities
  • Wavetable synthesis, FM synthesis, FM Sample synthesis, and AM synthesis
• A clock control block, incorporating timers, and a UART
• Joystick control

Motorola 68000 (processor #5)

• Runs at 13.295MHz
• General purpose control processor

Communication is performed with a high speed 64-bit data bus, rated at 106.364 megabytes/second. The 68000 is only able to access 16 bits of this bus at a time.

The Jaguar contains two megabytes (16 megabits) of fast page-mode DRAM, in four chips with 512 K each. Game cartridges can support up to six megabytes (48 megabits) of information, and can contain an EEPROM (electrically erasable/programmable read-only memory) chip to save game information and settings. Up to 100,000 writes can be performed with the EEPROM; after that, future writes may not be saved (performance varies widely, but 100,000 is a guaranteed minimum). Depending on use, this limit should take from 10 to 50 years to reach.

The Jaguar uses 24-bit addressing, and is reportedly capable of accessing data as follows:

• Six megabytes cartridge ROM
• Eight megabytes DRAM
• Two megabytes miscellaneous/expansion

All of the processors can access the main DRAM memory area directly. The Digital Signal Processor and the Graphics Processor can execute code out of either their internal caches, or out of main memory. The only limitations are that

1. "jump" instructions in main memory have certain restrictions; the JMP (unconditional jump) command is longword-aligned, while the JR (jump-indexed-by-register) command must be either word- or longword- aligned. And
2. running out of the cache is much faster (up to four times faster) and efficient.

Some believe that the inability to jump/branch in main memory makes the main memory feature useless.

Swapping data between the caches and the main memory is a quick, low overhead operation, and therefore the main memory is often used as "swap space" for cache code. The RISC compiler included in the latest Jaguar developer's kit produced code that transparently swaps code through the cache. This effectively allowed developers write RISC code without concern for the cache size limits.

Compressed cartridge data can be uncompressed in real-time, and ratios of up to 14:1 have been cited. In theory, a Jaguar cartridge can store up to 84 megabytes (672 megabits) of data, though actual results will vary widely (most often, images are compressed, while sound and code are not).

Compression is performed with BPEG, an enhanced JPEG image decompression mechanism. BPEG supercedes the former JagPEG algorithm, working up to 10 times faster and with more flexibility.

Other Jaguar features:

• Support for ComLynx I/O for communications with the Atari Lynx hand-held game system and networked multiconsole games (on DSP port, accessible by optional add-on connector). Networking of up to 32 Jaguar units available.
• The two controller ports can be expanded to support "dozens" of controllers
  • Digital and analog interfaces
  • Keyboards, mice, and light guns are possible
• Expansion port allows connection to cable TV and other networks
• Digital Signal Processor port allows connection to modems and digital audio peripherals (such as DAT players)
• One megabyte per second serial interface
• 9600 baud, RS-232 serial port (accessible with optional interface)
• General-purpose I/O bits via the cartridge port
• Can accommodate future expansions of different processor types, I/O types, video types, and memory types and/or quantities.

Was the Jaguar really a 64-bit system?

The question is hard to resolve, largely because the definition of what constitutes an "N-bit" system has not been set. Of the five processors in the Jaguar, only the object processor and the blitter are "true" 64-bit components. Because the blitter and the object processor are in the Tom chip, by extension Tom is a 64-bit chip. Furthermore, the Jaguar also used a 64-bit memory architecture, according to Jez San of Argonaut Software.

Some say the Jaguar should be considered a 32-bit system, as that is the maximum register size in the programmable processors (the 68000, the graphics processor, and the DMA sound processor). Others say the Jaguar can be considered a 64-bit system, because 64-bit components are used, and the GPU can access 64 bits of data if required. Again, the lack of an agreed-upon definition serves to complicate the issue.

According to Jaguar designer John Mathieson, "Jaguar has a 64-bit memory interface to get a high bandwidth out of cheap DRAM. ... Where the system needs to be 64 bit then it is 64 bit, so the Object Processor, which takes data from DRAM and builds the display is 64 bit; and the blitter, which does all the 3D rendering, screen clearing, and pixel shuffling, is 64 bit. Where the system does not need to be 64 bit, it isn't. There is no point in a 64 bit address space in a games console! 3D calculations and audio processing do not generally use 64-bit numbers, so there would be no advantage to 64 bit processors for this.

"Jaguar has the data shifting power of a 64 bit system, which is what matters for games, so can reasonably be considered a 64 bit system. But that doesn't mean it has to be 64 bits throughout."

For the record, the opinion of most third party developers and observers is that the Jaguar is indeed a 64-bit system. The emphasis is on the word "system"; while not every component is 64 bits, the Jaguar architecture, as a COMPLETE SYSTEM, is.

The Jaguar used a 68000. Isn't that the CPU?

Again, quoting from Jaguar designer John Mathieson, "It may be the CPU in the sense that it's the centre of operation, and boot-straps the machine, and starts everything else going; however, it is not the centre of Jaguar's power. ... The 68000 is like a manager who does no real work, but tells everybody else what to do."

And...

"Atari were keen to use a 68K family device, and we looked closely at various members. We did actually build a couple of 68030 versions of the early beta developers systems, and for a while were going to use a 68020.

However, this turned out too expensive. We also considered the possibility of no [Motorola 680x0 chip] at all. I always felt it was important to have some normal processor, to give developers a warm feeling when they start. The 68K is inexpensive and does that job well. I maintain that it's only there to read the joysticks."

In rebuttal, Jaguar developer Andrew Whittaker notes, "In practice, what many of us did with our titles was use the 68000 for AI and gameplay logic, and have the custom chips drive the rendering to screen and 3D code."

How could a graphics processor be the CPU?

The 64-bit custom graphics chip was a good general purpose RISC unit, but it had been optimized for graphics work. Developers were free to specify which processor(s) to use in a program, as desired.

What kind of special effects could the Jaguar do?

The Jaguar was capable of doing the following visual effects:

• High-speed scrolling (Object Processor).
• Texture mapping on two- and three-dimensional objects (GPU and Blitter).
• Morphing one object into another object (GPU).
• Scaling, rotation, distortion, and skewing of sprites and images (Object Processor).
• Lighting and shading from single and multiple light sources (GPU and Blitter).
• Transparency (Object Processor).
• "Rendering" up to 850 million one-bit pixels/second (35 million 24-bit pixels/second, 26 million 32-bit pixels/second), or 50 million Goroud shaded pixels/second. "Rendering" is believed to mean transferring a pixel from a frame buffer to the screen.
• Sprites of "unlimited" size and quantity. Realistically, sprites can be over 1,000 pixels wide/tall, and the number of sprites allowed is limited by processor cycles instead of a fixed value in hardware (Object processor).
• Programmable screen resolutions, from 160 to 800 pixels per line. The resolution can be increased even further with additional hardware up to a reported 1350 pixels per line.

One of the Jaguar modes is called "CRY mode", which supports lighting and effects in 3D graphics. Red, green, and blue color elements are ranged from 0 to 255, and the lighting level for any pixel can be changed by setting one byte linearly. E.g., the relative proportions of red, blue, and green are indicated with one byte, while a second byte selects an overall intensity of 0 to 255. CRY allows much smoother shading of single colors, but doesn't allow blending between colors as smoothly.

Actual graphics performance is hard to measure, as there are no industry- standard benchmarks. Rebellion Software has claimed that the Jaguar can render "10,000 Gourard shaded, large, 65536 color, any shape polygons per second," while still performing other tasks. Presumably this level can be increased further with optimized programming; indeed, some unofficial calculations speculate that FIGHT FOR LIFE may generate between 20,000 to 40,000 texture-mapped polygons per second.

A key to understanding the Jaguar's performance is to realize that most effects are accomplished by programming one of the processors to do the job. To perform texture-mapping, for instance, required a developer to write a texture-mapping routine for the GPU and/or blitter, then call it as needed. The general-purpose nature of the Jaguar architecture gave developers a lot of flexibility; unfortunately, the drawback was that software routines for such effects are invariably slower and less efficient than dedicated hardware chips and components.

Part II next month...
 

Last update: 4th December 2000

This file is not maintained by, overseen by, endorsed, or otherwise associated with Atari Corp., JTS, or any of its subsidiaries. It's just a collection of questions and answers, with a few news tidbits thrown in. Robert tries to get the latest news and information into this FAQ; however,he's only human, and might miss something important due to real-life demands.

The latest version of this FAQ is available here. Send corrections, news, updates, comments, questions or other stuff to rjung@mac.com.
 

MyAtari magazine - Feature #2, January 2001