Architecture of the Atari Lynx

The Atari Lynx is a handheld console that has two form factors over its lifetime. The Lynx I and II models have a different casing and internal layout, but hold nearly exact same electronic hardware. The main difference is lower power consumption and stereo sound (but less loud) for the Lynx II incarnation.

258_61175232 Atari_Lynx_II_1BF4E657

Atari Lynx I and II handhelds

The Lynx had two processors running nicknamed Mikey and Suzy. Mikey, a custom 65SC02 chip, supported the sound engine and the video driver, the system interrupts and timers, ComLynx support and ran at 4 MHz. Mikey was also responsible for loading the games with the 512 bytes of ROM it had for that function. Suzy supported the graphics engine and a math co-processor and ran at 16 MHz. Game cards support up to 2 MB of ROM, but most contain either 128K or 256K, with only 3 games supporting 512K.

The various chips inside the machine are:

  • U1: (Mikey, see below)
  • U2: (Suzy, see below)
  • U3 and U4:
    Lynx I – HM-50464-12
    Lynx II – HY53C464LS-10 (Two 256 KB DRAM chips (64K X 4 nMOS general purpose Dynamic RAM, page-mode operation DIP-18, 256 cycles/4 msec)
  • U5: LM386 (Low voltage audio power amplifier)
  • U6: 4069 (CMOS Hex Buffer)
  • U7: 74HC04 (Hex inverter, used multiple times)
  • U8: 74HC4040 (12-stage binary ripple counter; generates cartridge addresses A0-A10)
  • U9: 74HC164 (8-bit serial-in, parallel-out shift register; generates cartridge addresses A12-A19)
  • U10: S-8054 (Voltage detector)
  • U11: 74HC74 (High Speed CMOS Logic Dual Positive-Edge-Triggered D-Type Flip-Flops with Set and Reset; controls backlight on/off)
  • U12: NJM2073 (Dual low voltage range power amplifier; stereo sound output)

U10, U11 and U12 are on Lynx II only.

Mikey
8-bit custom CMOS chip running at 4MHz

MOS 65SC02 Processor running at up to 4MHz (~3.6MHz average) 8-bit CPU, 16-bit address space
Sound engine 4 channel sound 8-bit DAC for each channel (4 channels x 8-bits/channel = 32 bits commonly quoted)
Lynx II has panning support
Atari reports the range is “100Hz to above the range of human hearing”; spectrum analysis shows the range may go as low as 32Hz.
Stereo with panning (mono for original Lynx)
Video DMA driver Video DMA driver for LCD display
4096 color (12-bit) palette
16 simultaneous colors (4 bits) from palette per scanline (more than 16 colors can be displayed by changing palettes after each scanline)
System timers 8 System timers (2 reserved for LCD timing, one for UART)
Interrupt controller
UART (for ComLynx) Universal Asynchronous Receive/Transmit
Fixed framing format 8E1 (meaning an 8-way connection between two “users”)
Baud rate up to 62500Bd
512 bytes ROM Bootstrap and game-card loading ROM

Suzy
16-bit custom CMOS chip running at 16MHz

Blitter unit Bit-map block transfer unit
Graphics engine Hardware drawing support
Unlimited number of high-speed sprites with collision detection
Hardware high-speed sprite scaling, distortion, and tilting effects
Hardware decoding of compressed sprite data
Hardware clipping and multi-directional scrolling
Variable frame rate (up to 75 frames/second)
160 x 102 “triad” standard resolution (16,320 addressable pixels) (A triad is three LCD elements: red, green, and blue)
Capability of 480 x 102 artificially high resolution
Math co-processor Hardware 16-bit multiply and divide
16-bit × 16-bit → 32-bit multiply with optional accumulation;
32-bit ÷ 16-bit → 16-bit divide
Parallel processing of CPU and single multiply or divide instruction
Controller Input Handles input from joypad, pause, option and fire buttons

Parts of the Mikey and Suzy information was taken from the Atari Lynx FAQ, which has more detailed information on all physical aspects of the Atari Lynx.

Bastian Schick has the electronic schematics up on his website (in a single ZIP file, but with two images of board split in left and right side). He also has a file listing the pin layout of the cartridge port.

lynx_ii_21A978D5

Another famous Lynx developer Matthias Domin has the Lynx I and Lynx II opened up and describes what part is what.

Opened Lynx II (turned around)

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8 Responses to Architecture of the Atari Lynx

  1. Johney says:

    The ultimate portible color 16bit system of the 80’s.

    • alexthissen says:

      To be precise, the Lynx was “only” an 8-bit machine with a coprocessor that can do 16×16 bit multiplications and divisions. Smart marketing to call it 16-bit, even though the 65C02 was really 8-bit.

  2. atariandre42 says:

    U6 is a hex buffer , not a 16mhz oscillator……

  3. atariandre42 says:

    Your’re welcome, I really like this website a lot, lots of great Lynx info ! And the (only?) place I could find a complete list of the chips used 🙂 I noticed the mistake as I’m hacking a lot of stuff on my Lynx at the moment.

    Well, technically speaking there is no oscillator on the Lynx, in the sense that it is not a separate unit as can be seen in some more modern desgins (metal case with crystal plus added parts). Instead there is just the crystal which is connected with only two resistors (one in series, one in parallel) to Mikey. Obviously Mikey has the rest of the parts need to complete the oscillator built-in.

    This kind of use of a separate crystal was common in the early 80’s, dedicated oscillators came later as far as I remember.

    The crystal is indicated as Y1 on my Lynx I and it is positioned under the cartridge connector.
    The schematics of Lynx II also mention Y1 as the part number.

    U6 is used to handle the power on-power off buttons.

    Seeing you buy on Marktplaats and have a lot of Dutch flyer scans I guess you are from The Netherlands too ? Are you on Atariage forums ?

    • alexthissen says:

      Thanks again for the comments. Updated the document again.
      Yes, from The Netherlands, close to ‘s-Hertogenbosch. I am also on AtariAge where my name is LX.NET. Where are you from in The Netherlands?

  4. atariandre42 says:

    U10 is a S-8054 which is a voltage detector. This is only present on Lynx II as it seems to be used to provide a signal for the LED. Lynx I has no LED.

    Not sure if the U numbering above U10 is the same between Lynx I and II, have to check the schematics.
    If they are 100% the same and U10 is missing on the Lynx I it gives me the feeling that it has been intended to be there from the start by Atari may have decide to skip it to save a few cents…..but changed their mind again with the II.

  5. André says:

    Well I learned a bit more about U6. I was right about it controlling the on/off buttons but the other buffers in it are part of the oscillator which forms the switching power supply of the Lynx. That is not running at 16Mhz though (which is the crystal’s frequency) but it’s probably working somewhere between 60 and 100kHz.

    I studied the schematics a bit more.

    Lynx I only had U1 up to U9.

    Lynx II added U10, 11 and 12.

    U11 is a 74HC74 as you mention. It was added to control the backlight on/off which was a new feature on Lynx II.

    U12 is not a LM386 but a NJM2073 dual low voltage range power amplifier. This was
    added because of the Stereo sound output of the Lynx II.(http://www.njr.com/semicon/PDF/NJM2073_E.pdf).

    There….I think everything is correct now 🙂

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