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 accomodate future expansions of different processor types, I/O
types, video types, and memory types and/or quantities.
