This document details the signals found on the internal video slot of the Amiga 2000 (A2000), and the additional component of this slot as implemented on the B2000 version of the A2000 computer. Introduction€ This document details the signals found on the internal video slot of the A2000, and the additional component of this slot as implemented on the B2000 computer. The A2000 video connector is a 36 pin edge connector mechanically similar to the slot extension conector of an IBM PC-AT. The B2000 adds a second 36 pin connector, directly in front of to the first one, that supplies additional audio/video information. Where possible, a device should use only the first slot, thus maintaining compatibility with both A2000 and B2000. Of course, there are quite a few things that can't be accomplished with the A2000 connector alone. Original A2000 Slot€ The original A2000 video slot was designed to provide the functionality of the 23 pin external video connector in a form that could internally house video boards such as modulators, genlocks, etc. „Power Connections€ The Video Slot provides several different voltages designed to supply Video devices. The A2000 power supply is currently rated at 200 Watts, which supplies the main board and all other expansion ports as well as the Video Slot. ‚Video Ground€ Video supply ground used by all video devices and the internal video circuitry. Currently on the B2000 the Video and Digital grounds are common signals, while on the A2000 these are distinct. This is available on pins 9, 12, 13, 17, 20, 21, 24, 32. ‚Main Supply (+5V)€ Main digital level power supply the Video Slot. This can supply large currents. This connection is speced at 1 Amp, though with proper power budgeting can supply as much as 4 Amps. The maximum supply currert for the entire A2000 system is 20 Amps for all devices inside the A2000 that use +5V, including the motherboard. Pins: 6, 8. ‚Negative Supply (-5V)€ Negative version of the main supply, for small current loads only; there's a total of 0.3 Amp for the entire A2000 system. Pin: 31. ‚High Voltage Supply (+12V)€ Higher voltage supply, intended for small loading only; there's a total of 8 Amps for the entire A2000 system, much of which is normally devoted to floppy and hard disk drive motors. Pin: 10. „Clock Signals€ These are various clock signals useful for synchronous timing of video peripherals. ‚/C1 Clock€ This is a 3.58 MHz clock (3.55 MHz on PAL systems) that's synched to the falling edge of the 7M system clock. Also known as /CCK in some places. Pin 34. ‚/C4 Clock€ This is a 3.58 MHz clock (3.55 MHz on PAL systems) that's synched to the rising edge of the 7M CDAC clock. Pin 19. ‚External Clock (XCLK, /XCLKEN)€ The video slot provides for an external system clock, generally used to cause the entire A2000 system to become synchronized to something external. This should be something very close to the 28.64 MHz clock normally used to drive the system; the value used for XCLK can be a somewhat higher frequency, though anything too high will cause memory and other system timings to break down. XCLK will only be engaged as the system clock when /XCLKEN is asserted. XCLK is found on pin 33, /XCLKEN is on pin 16. There is no fixed phase relationship between XCLK and the internal clocks and video output. Video interfaces must synchronize to the output clocks/video (of course, video interfaces often provide their own video sync information). „Video Signals€ The main point of this slot is access to the video signals generated by the Amiga's custom video chips. Most of these are also found on the 23 pin external video connector. ‚Analog Video€ This is the analog RGB output, which consists of Red, Green, and Blue signals each of which generates a 0.7V p-p, 47 Ohm ternimated, analog output. Found respectively on pins 7, 11, and 15. ‚Digital Video€ These signals serve as digital output, suitable for use with an IBM or Commodore 128 style 4 bit digital color or monochrome monitor or similar output device. On the B2000, these in conjuction with other signals found on the second video connector provide access to the full 12 bits of digital video output produced on the motherboard by the Denise chip (4 bits each of R, G, and B). Each of these outputs is 47 Ohm terminated. The pin assignments are Digital Red (R3) on pin 29, Digital Green (G3) on pin 27, Digital Blue (B3) on pin 25, and Digital Intensity (B0) on pin 23. ‚Separate Sync (/HSYNC, /VSYNC)€ These are the separate, bidirectional, 47 Ohm terminated video frame synchronization clocks. The horizontal sync, /HSYNC, is on pin 22, the vertical sync, /VSYNC, is on pin 26. As the names imply, these sync signals are active low. ‚Composite Sync (/CSYNC, COMP SYNC)€ Two versions of a composite synchronization signal are available. Pin 14, /CSYNC, is an unterminated digital level composite sync; pin 28, COMP SYNC, is a version of the combined synchronization clocks created by the Video Hybrid. ‚BURST€ NTSC/PAL colorburst. Pin 18. To obtain the correct PAL color burst signal, the video plug in card must multiply this signal by 1.25 (i.e. 3.55 * 1.24 = 4.433 MHz). ‚Pixel Switch (/PixelSW)€ Background color indicator (color 0), on a pixel by pixel basis. 47 Ohm terminated, /PixelSW, pin 30. „Audio Signals€ Along with access to video signals, audio signals are available at the Video Slot. The audio signals are the Left and Right audio channels, on pins 3 and 4 respectively. „Reserved For Expansion€ The original Video Slot has pins 1, 2, 5, 35, and 36 reserved for future expansion. B2000 Extended Video Slot€ The B2000 Extended Video Slot was designed to provide nearly every internal video signal available, plus additional audio signals and some control lines too. This slot allow much more complex and powerful devices to be placed in the video slot. „Power Connections€ The Extended Video Slot provides several different voltages designed to supply Video devices. The A2000 power supply is currently rated at 200 Watts, which supplies the main board and all other expansion ports as well as the Video Slot. ‚Digital/Video Ground (Ground)€ These pins provide additional grounding for digital or video based devices. The timing of the digital video is not tightly specified. Developers wishing to use this digital data should contact Commodore-Amiga for additional details on this. Pins 1, 5, 9, 12, 22, and 32. ‚Audio Ground€ These pins provide grounding in common with the separate on-board audio ground. Pins 34, 36. „Clock Signals€ These are various clock signals useful for synchronous timing of video peripherals. ‚CDAC Clock€ This is a 7.16 MHz clock (7.09 MHz on PAL systems) that leads the 7M system clock by about 70ns (90 degrees). Pin 15. ‚/C3 Clock€ This is a 3.58 MHz clock (3.55 MHz on PAL systems) that's synched to the rising edge of the 7M system clock. Also known as /CCKQ in some places. Pin 17. ‚Timer Time Base (TBASE)€ This is the real time clock time-base input, either 50Hz or 60Hz depending on the country involved and the setting of the Time Base Jumper. The jumper can select either line frequency or vertical synchronization as the clock's time base. Pin 14. „Video Signals€ The main purpose of this slot is to provide access to more of the video signals generated by the Amiga's custom video chips. Most of the signals available here aren't available on any external port. ‚Composite Video€ This is the analog level monochrome Composite Video signal also available on the Composite Video jack of the B2000. Pin 13. ‚Digital Video€ The remaining 8 bits of digital video are available on this connector. The signals are Red 0-2 (pins 2, 3, 4), Green 0-2 (pins 6, 7, 8), and Blue 1-2 (pins 10 and 11). ‚Light Pen (/LPEN)€ This is an input to the Agnus light pen input. This signal should go low in response to the lighting of a pixel on a video display monitor. The Agnus chip latches the raster position that was in effect when the /LPEN signal goes low, so an application can follow the position of a light pen on the screen. Pin 19. „Port Connections€ Most of the signals from the bidirectional parallel port (printer port) are available on this connector as well, along with a few others. ‚8 Bit Parallel Port (PD0-PD7)€ The 8 bit bidirectional parallel port most commonly used to drive a Centronics interface printer externally is accessable here. It can be used to control various aspects of a complex video interface device. The port lines PD0-PD7 are on pins 23 to 30 of this connector. ‚Parallel Port Handshake (/ACK)€ This is the acknowledge (/ACK) input, the same as the acknowledge input to the parallel port. Driving this with an output from a Video Card can cause a level 2 interrupt to occur through the 8520 CIA device this is connected to, based on the programming of an 8520 register. On pin 20. ‚Other Port Lines (BUSY, POUT, SEL)€ Connector pins 18 (BUSY) and 16 (POUT) are general purpose I/O signals that together can also function as a synchronous serial data port driven by an 8520 CIA device. In normal printer use, the BUSY signal is used to indicate printer buffer full to the Amiga, while POUT is used to indicate the printer paper is out. For serial port usage, BUSY is the serial clock, POUT is the serial data line. These should be driven with open collector devices if the Video Card uses them as inputs to the 8520. The SEL signal, on pin 21, is a general purpose I/O port, usually used as a device select signal on the parallel port. „Audio Signals€ The B2000 Extended Video Slot offers a few additional audio signals. ‚Raw Audio€ These are the left and right audio channels before they're passed through the low pass filter on output. For many applications, the audio sampling rate is low, and as such requires a low pass filter to be in place at fc = 6 kHz or so, to pervent audio alaising. However, higher sampling rates are possible, and in such cases, a much higher filtering frequency is required for best possible sound. This raw audio, left on pin 33 and right on pin 35, is buffered but unfiltered. ‚Filter Cutoff (/LED)€ This is the /LED port line. In the B2000, as per the A500 convention, this signal is used to cut out the two pole low pass filter on the standard audio channels. When asserted, the filter is in place; when negated the filter is bypassed. This is an input to this Video connector, useful to allow any Audio/Video card to monitor the audio filtering state. Pin 31. Appendix€ The original A2000 video slot is a 36 pin edge connector, the same type as used on the A2000's 16 bit IBM style bus extension. Commodore-Amiga March 15, 1987 1 Reserved for Expansion 3 Left Audio Out 5 Reserved for Expansion 7 Analog Red 9 Video Ground 11 Analog Green 13 Video Ground 15 Analog Blue 17 Video Ground 19 /C4 Clock 21 Video Ground 23 B0 = DI (47 Ohm) 25 B3 = DB (47 Ohm) 27 G3 = DG (47 Ohm) 29 R3 = DR (47 Ohm) 31 -5 VDC 33 XCLK 35 Reserved for Expansion 2 Reserved for Expansion 4 Right Audio Out 6 +5 VDC 8 +5 VDC 10 +12 VDC 12 Video Ground 14 /CSYNC 16 /XCLKEN 18 BURST 20 Video Ground 22 /HSYNC (47 Ohm) 24 Video Ground 26 /VSYNC (47 Ohm) 28 COMP SYNC (Analog) 30 /PixelSW (47 Ohm) 32 Video Ground 34 /C1 Clock 36 Reserved for Expansion as used on the 16 bit IBM style bus extension. 1 Ground 3 R1 5 Ground 7 G1 9 Ground 11 B2 13 Composite Video 15 CDAC Clock 17 /C3 Clock 19 /LPEN 21 SEL 23 PD0 25 PD2 27 PD4 29 PD6 31 /LED 33 Raw Audio Left 35 Raw Audio Right 2 R0 4 R2 6 G0 8 G2 10 B1 12 Ground 14 TBASE 16 POUT 18 BUSY 20 /ACK 22 Ground 24 PD1 26 PD3 28 PD5 30 PD7 32 Ground 34 Audio Ground 36 Audio Ground