CD32 Expansion-port

The Commodore CD32 expansion port is a 182-pin connector sharing the same physical form factor as the IBM Micro Channel Architecture (MCA) connector. Introduced with the CD32 games console in 1993, it exposes the full AGA chipset bus — the same architecture used in the Amiga 1200 and Amiga 4000 — along with RGB analogue video taken directly from the digital-to-analogue converter outputs, digital audio input for mixing external MPEG or FMV audio with the CD audio and Amiga audio streams, and genlock signals. The port was designed primarily to accept the Full Motion Video (FMV) MPEG cartridge and SX-1/SX-32 type expansion units that added a keyboard, floppy drive, IDE interface, and serial/parallel ports to the otherwise console-only machine.

182 PIN CONNECTOR (SAME AS MCA) at the computer

Notes

The connector is mechanically identical to the IBM MCA (Micro Channel Architecture) edge connector at 182 pins, though the signal assignments are entirely Commodore-specific. The CD32 uses a 68EC020 processor running at approximately 14 MHz; address lines A31–A24 are present on the connector but are not driven by the 68EC020 (which has only a 24-bit physical address bus) and are most likely unconnected. All logic signals are 5 V TTL-compatible. Power rails available are +5 V (multiple pins) and +12 V; expansion units must not exceed the current budget of the CD32’s internal supply. The RGB analogue video signals (AR, AG, AB and their _EXT counterparts) are taken directly from the AGA DAC outputs and are not buffered at the connector, so expansion units performing genlock or overlay operations must provide their own signal conditioning.

Signals

• A31–A0 — 32-bit address bus from the 68EC020; A31–A24 are likely unconnected internally due to the EC020’s 24-bit physical address limit
• D31–D0 — 32-bit data bus
• DGND — digital ground reference for bus signals
• VCC — +5 V DC supply for expansion logic
• /IPL2, /IPL1, /IPL0 — active-low interrupt priority level inputs to the 68EC020, encoding the current interrupt level
• /RST — system reset signal
• /HALT — processor halt signal
• /ECS, /OCS — chipset compatibility identification signals (Enhanced Chip Set / Original Chip Set select lines; exact function on AGA CD32 uncertain)
• SIZE1, SIZE0 — indicate the number of bytes remaining to be transferred in the current bus cycle (68020 dynamic bus sizing)
• /AS — address strobe; asserted when the address bus contains a valid address
• /DS — data strobe; asserted when the data bus is valid (write) or to request data (read)
• /R/W — read/write direction line; high = read, low = write
• /BERR — bus error; asserted to signal an error condition on the current bus cycle
• /AVEC — autovector request; asserted during interrupt acknowledge to request an autovector rather than an externally supplied vector
• /DSACK1, /DSACK0 — data transfer and size acknowledge lines used by the 68020 for dynamic bus sizing and to terminate a bus cycle
• CPUCLK_A — CPU clock signal (approximately 14 MHz)
• FC2, FC1, FC0 — function code outputs from the 68EC020 indicating the address space type of the current bus cycle
• /CPU_BR — CPU bus request; used by an expansion device to request mastership of the local bus
• /EXP_BG — expansion bus grant; asserted by the CPU to grant bus mastership to a requesting expansion device
• /CPU_BG — CPU bus grant output
• /EXP_BR — expansion bus request; alternate bus request line for expansion devices
• /PUNT — signal allowing an expansion device to pass a bus cycle back to the on-board logic
• /RESET — 68020 RESET instruction output; can be used to reset peripherals
• /INT2 — generates a level 2 interrupt to the processor
• /INT6 — generates a level 6 interrupt to the processor
• /KB_CLOCK — keyboard clock line (used by SX-1/SX-32 type keyboard expansion units)
• /KB_DATA — keyboard data line
• /FIRE0, /FIRE1 — joystick fire button inputs (exact routing uncertain)
• /LED — power-on LED control (exact function uncertain)
• /ACTIVE — floppy/disk activity LED
• /RXD — serial receive data input
• /TXD — serial transmit data output
• /DKRD — floppy read data (Paula chip interface)
• /DKWD — floppy write data (Paula chip interface)
• SYSTEM — system signal (function not fully documented)
• /DKWE — floppy write enable (Paula chip interface)
• CONFIG_OUT — AutoConfig daisy-chain output; allows self-configuring expansion cards to be sequentially mapped into the Amiga address space during boot
• +12V — +12 V DC supply
• 17MHZ — 17 MHz clock, provided for the FMV (Full Motion Video) MPEG module interface
• EXT_AUDIO — external audio input for mixing MPEG/FMV audio with the CD and Amiga audio streams
• DA_DATA — digital audio serial data (I²S-style interface for FMV audio)
• /MUTE — audio mute control (FMV interface)
• DA_LRCLK — digital audio left/right word clock (FMV interface)
• DA_BCLK — digital audio bit clock (FMV interface)
• DR, DG, DB — digital red, green, blue video signals from the AGA chipset
• DI — digital intensity/brightness signal
• /PIXELSW_EXT — external pixel switch input (genlock/overlay use)
• /PIXELSW — pixel switch output
• /BLANK — composite blank signal
• PIXELCLK — pixel clock for synchronising manipulation of the RGB data stream
• /CSYNC — composite sync output; not buffered at the connector
• CCK_B — colour clock (3.58 MHz NTSC or PAL equivalent)
• /HSYNC — horizontal sync
• /VSYNC — vertical sync
• VGND — video ground reference for analogue video signals
• AR_EXT, AG_EXT, AB_EXT — external analogue red, green, blue inputs for genlock overlay mixing
• AR, AG, AB — analogue red, green, blue outputs from the AGA DAC; taken directly from the converter leads
• /NTSC — NTSC/PAL mode identifier signal
• /XCLKEN — enable external video clock input (genlock)
• XCLK — external video clock input (genlock reference)
• /EXT_VIDEO — when asserted, disables the CD32’s internal video output interfaces
• AGND — audio ground reference
• LEFT_EXT, RIGHT_EXT — external left and right analogue audio inputs for mixing
• LEFT, RIGHT — left and right analogue audio outputs

References

• CD32 Developer Notes, Revision 3 — Commodore Amiga, Inc., August 1993
• Amiga Hardware Reference Manual, 3rd Edition — Commodore-Amiga Inc., 1991

Category:Buses Connectors