Re: Ang: Re: Ang: Ang: Re: Commodore 1901 Monitor?

From: Raymond Computer (
Date: 2002-10-29 22:58:44

On 29-Oct-02, Mikael Holm wrote:

>>>The D-9 connector? What cable do I need to use that from my C128? Just a
>>>cable with a D-9 in both ends that connects pin 1 on the C128 to Pin 1 on
>>>the monitor, etc?

>>The DB9 _MUST_ have pin 7 disconnected (usually at the C=128 end)!
>>Else the Composite MONO video will confuse the 1901 decoder chip.
>>But all other wires are straight through.

>The cable I use now connects all pins from the C128 to all pins on the 1901
>and it works fine...
>What do you mean would happen when Composite Mono video will confuse the
>1901? It seems to work fine for me.

I do not have specific schematics for the 1901 but on some RGBI or CGA 
monitors including the 1902, 2002, some 1084s, if there is a signal
on Pin 7 which carries combined horizontal and vertical sync with monochrome
NTSC analog composite video, the chips on the circuit board do not have
a way to tell which sync signal(s) to use.  It maybe that your 1901 has 
pin 7 un-connected internally. 

-- Ray

|Raymond C. Bryan  651-642-9890 vox | The battle is sometimes |
|Raymond Computer  651-642-9891 fax | to the small for        |              
|795 Raymond Ave   -email:  raycomp | the bigger they are     |
|St Paul MN  55114     | the harder they fall.   |
|USA              Amiga - Commodore |     -- James Thurber -- |
|     |                         |

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