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10/08/07: Amiga 1080 monitor by mdelyea, | Category: General | 8 comments - (Comments are closed)

Amiga 1080 monitor

Hi all! Well, here I go again trying to get this monitor working with my coco. It has a 9 pin D type male connector on the back. I couldn’t find a pinout for this specific monitor, the closest I found was for the 1084. I am under the impression they are the same (from looking on the web). I made an inverter with a 74ls04 to invert the horizontal and vertical sync signals but that didn’t work. On closer inspection of the pinout diagram I see that the analog rgb doesn’t use separate hsync and vsync but instead uses csync (composite sync). I think I might be wasting my time trying to get this working with my coco. Other people have said they were able to get this combo working, but I’m sure they were talking about a 1080 with the 6 pin din connector (which does have separate hsync and vsync). So, unless anybody has some idea of how to get this working I’ll probably bin it.

8 comments to Amiga 1080 monitor

  • mdelyea

    Has anybody tried converting hsync and vsync to csync using the AD722? I was looking at this chip and it looks like it can take in the 2 syncs and convert into one csync. It can also combine R,G and B into chrominance and luminance but I wouldn’t be using that part of the chip.

  • mdelyea

    Ok, I got it working using a 74ls02. Fairly easy once you get the right chip and pinout.

  • RobertGault

    You would do a service for the Coco community if you would write a short article including a circuit diagram and post it on this site.

  • mdelyea

    Hmmm, OK. But be warned, my diagram will not actually contain the “official” symbols as I find those hard to decipher as a novice.

  • mdelyea

    Ok, I wrote it up and added ASCII diagrams, but when I tried to post it in the articles area my diagrams got messed up. Is there a way around this because my diagrams make absolutely no sense the way it is.

  • mannequin

    Try a code tag.

    This is a test of the code tag.
    — — —— — — ——
    — — — — — — —
    —— —— — — — —
    — — — — — — —
    — — —— —— —— ——


  • mdelyea

    [code:1:80a15526e3]I picked up an old Amiga 1080 monitor for next to nothing and

    wanted to use it for my coco because I had heard it was a good

    display for the 80 column mode. The first difficulty I ran into

    interfacing the 1080 and the coco was the lack of an available

    pinout for the 1080’s RGB connector. Further research eventually

    yielded the information that the 1084 pinout was the same as the

    1080. After finding the correct pinout (at and making

    a couple false starts I eventually found the correct information I

    needed to make this combination work. One of the mistakes I made

    was getting the HSYNC (horizontal sync) and VSYNC (vertical sync)

    signals going to the monitor correctly. At first I assumed (for

    various reasons) that I needed to invert the HSYNC and VSYNC so I

    made up a little circuit using a 74ls04 hex inverter chip. This

    didn’t work and was completely off the mark as I later found out

    (these chips are maybe 50 cents each so it wasn’t a big deal

    moneywise). Then as I was glancing through an old Rainbow I came

    across the information I needed in Marty Goodman’s column. The

    chip I actually needed was a 74ls02 NOR gate to combine the HSYNC

    and VSYNC into one CSYNC (composite sync). So I made up another

    little circuit using a 74ls02 and 14 pin socket, an LED, a switch

    and an external 5 volt power supply. I had originally intended to

    grab 5 volts from the coco internally but I just wanted to get this

    thing working and it was easier to use the external power supply.

    If you want to try this yourself be warned – this only works if you

    have a 1080 (or 1084) with the 9-pin D-type RGB connector, not the

    round 6-pin DIN type connector. If your monitor has the DIN

    connector you lucked out – you won’t have to add any circuitry at


    Parts list:

    14 pin 74ls02 NOR gate (dual input)
    14 pin socket
    Switch (I used a double pole single throw slider I had laying

    5 volt power supply (I used 5volts 200 mA)
    1k ohm resistor (I didn’t need it and you won’t either if you get

    the right LED)
    A small project board to attach everything to

    Note: For your power supply you need 5 volts and keep the milliamps

    below 400. Also, you might have to test the lines for positive and

    negative if you bought the power supply at a surplus store (like I

    did). If you don’t know which line is positive and which is

    negative it won’t work and you might let the magic smoke out. You

    can use a mulitmeter to find out which is which.

    The Cable

    For the actual cable I cobbled together a 10 pin header with ribbon

    cable attached (from an old motherboard serial port connector), a 9

    pin D type connector with ribbon cable attached (again from another

    old serial port), and a length of Ethernet cable. Special care

    must be taken when connecting the D end. The wires are not

    sequential with the pins! Pin 1 is wire 1, pin 2 is wire 3, pin 3

    is wire 5, pin 4 is wire 7 and so on.

    The Pinouts

    Coco (looking at the bottom with the back of the coco facing away

    from you)

    2 4 6 8 10
    1 3 5 7 9

    1 ground
    2 ground
    3 Red
    4 Green
    5 Blue
    6 No pin
    7 Sound
    8 HSYNC
    9 VSYNC
    10 Not used

    Amiga 1080 RGB D-type (looking at the back of the monitor)

    1 2 3 4 5
    6 7 8 9

    1 ground
    2 ground
    3 Red
    4 Green
    5 Blue
    6 Not used
    7 CSYNC
    8 Not used
    9 Not used

    Note: Pins 6, 8 and 9 are used with other computers, just not the


    Cable Assembly:

    I started at the coco end, attaching pins 1, 2, 3, 4, 5, 8 and 9 to

    the Ethernet cable. The Ethernet cable is conveniently

    colour-coded so make a note of what wire goes to what colour (eg.

    pin 1 to blue, pin 2 to blue/white etc.). At the Amiga end I

    attached the corresponding wires to pins 1, 2, 3, 4 and 5 (making

    sure I followed the wiring scheme I noted earlier wherein pin 1 is

    wire 1 and pin 2 is wire 3 and so on). When you’ve finished this,

    check the connections for continuity using a mulitmeter.

    The Circuit Board:

    —– + ——./ .—–w—–|O|———————-|
    | 5v | resistor LED ______ |
    —– 1-| 7 |-14—-
    neg 2-| 4 |-13
    | 3-| L |-12
    | 4-| S |-11
    | 5-| 0 |-10————|
    | 6-| 2 |-9——-| |
    |———————————– 7-| |-8–| | |
    ——- | | |
    | | |
    From coco pin 8 ————| | |
    From coco pin 9 —————–| |
    To Amiga pin 7 ———————–|

    Connect +5 to the switch and run it to the LED. Make sure you have

    the LED oriented correctly or it won’t work – usually the long wire

    is positive. Also, unless you have an LED with a built in resistor

    (mine does) you should put a resistor in front of the LED (a 1k ohm

    resistor will do in a pinch). Connect the negative end of the LED

    to pin 14 of the 74ls02 and attach pin 7 to the negative side of

    the power supply. Attach wire 8 from the coco to pin 8 of the

    74ls02 and wire 9 from the coco to pin 9 (easy eh!). Now attach

    the wire from pin 7 of the Amiga’s RGB to pin 10 of the 74ls02.

    When you turn the switch on the LED should light. If it doesn’t

    light up then check your connections (and didn’t I warn you about

    the resistor?).

    My circuit board looks a bit messy right now so I’m going to redo

    it and pack it into a little project box I picked up for $2.00. I

    think I’ll even add a jack for the power supply.

  • mdelyea

    I forgot to mention that this project doesn’t include a connector for sound. The 1080 has a mini jack on the left side for sound so I guess you could make up a little cable with an RCA jack on one end and the mini jack on the other then connect the RCA jack to the audio out on the coco.