Re: Apple //e RGB Card to CGA pinout?

["Bryan Parkoff" <nospam@nospam.com>]

"Knut Roll-Lund" <kr-lund@nogarbage.online.no> wrote in message 
ENKdnYfyfr5rUb3eRVnzvA@telenor.com">news:ENKdnYfyfr5rUb3eRVnzvA@telenor.com...
> Knut Roll-Lund wrote:
>
>> Bill Garber wrote:
>>
>>> "Knut Roll-Lund" <kr-lund@nogarbage.online.no> wrote in message 
>>> z9OdnfhWpN7c-b3eRVnzvA@telenor.com">news:z9OdnfhWpN7c-b3eRVnzvA@telenor.com...
>>>
>>>> Mark McDougall wrote:
>>>>
>>>>
>>>>> Bill Garber wrote:
>>>>>
>>>>>
>>>>>> IIRC, CGA monitors accept Composite Sync on the Horizontal Sync pin.
>>>>>> I'd have to research it again to be sure. Been a long time.
>>>>>
>>>>>
>>>>>
>>>>> Yeah, that's exactly what I was thinking when I first read the post... 
>>>>> so ditto from me.
>>>>>
>>>>
>>>> I will try it... the CGA monitor too then and report back my result. 
>>>> The Mitsubishi is like that, it can use composite sync on the same 
>>>> terminal which is Horizontal when using separated syncs.
>>>>
>>>> I read in the Mitsubishi manual that it should be possible to have the 
>>>> syncs composite on the green input too, but that doesn't work because 
>>>> then the normal monocrome video output should work on the green input. 
>>>> It just swims no sync.
>>>
>>>
>>>
>>>
>>> Well, you can't just attach the sync signal to the green,
>>> it has to be incorporated digitally.
>>>
>> It wasn't the sync, it was mono composite video.
>>
>> And, yes I know, and probably not just digitally, it is also a special 
>> level. I'm not sure but I though a normal mono composite video would be 
>> similar to what that green+sync input expects. It might of course be 
>> different so that is why it didn't work. Applying this mono composite 
>> signal to the blue or red inputs would produce exactly the same result.
>>
>> I have the RGB card now so I'll soon be back with some more test results 
>> (it at least works as a normal 80columns 128k card...)
>>
> I first made a straigt converter from DB-9 to DB-15 for the CGA monitor 
> (IBM 5153) I put the composite sync signal to the horizontal input. It was 
> no success the picture came though clear but wouldn't stop rolling. I 
> think vertical sync is needed unfortunately.
>
> I then made a quick adapter for the mitsubishi monitor without the 
> resistors to display "8 colors". It wasn't a success either. The picture 
> was stable but the screen was garbeled. It seemed to me that horizotal 
> sync wasn't working, that the lines were too long or too short. making 
> each scanline not in sync with the next. Either there is a problem with 
> the levels or the monitor might be broken (I will open it and see if there 
> is anything to adjust.
>
> The olivetti needs both syncs separate...
>
> Knut
Knut,

    I am concerned that CGA is like analog RGB, but not digital RGB. 
Michael M. claims that most CGA monitors connect to ISA card for PC should 
be digital RGB.  If you already connected CGA monitor to PC and it is 
working fine with no problem, then the configuration from Apple //e RGB card 
to CGA monitor is wrong according to my theory.
    I encourage to compare the schematic from Apple //c's video port to 
Apple //e RGB card so it might give you an idea how to build an adapter.  An 
adapter should contain one or more chips to manipulate H sync and V sync. 
Please comment what you have made some attempts when progress is going on. 
Thanks...

Bryan Parkoff