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


"Knut Roll-Lund" <kr-lund@xxxxxxxxxxxxxxxxxxx> wrote in message
news:nOmdncGo5YZkgrne4p2dnA@xxxxxxxxxxxxxx
> Knut Roll-Lund wrote:
>> Bryan Parkoff wrote:
>>> "Knut Roll-Lund" wrote:
>>>> Knut Roll-Lund wrote:
>>>>> Bill Garber wrote:
>>>>>> "Knut Roll-Lund" wrote:
>>>>>>> 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.
>>>>
>>> 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...
>>>
>> Well, you can see I have posted a lot of messages in this thread now.
>> Maybe all of these tidbits aren't of interest to all so you might email
>> me remove 'nogarbage.' from the email address to reply directly to me. It
>> might be better to present the results to the group. We are probably
>> trying to do something similar.
>>
>> I traced the composite sync signal back in the 2e. On the RGB card it
>> goes through two inverters (20ns delay...) in an LS04 and comes from the
>> mainboard. Here it is generated by a 40 pin ic next to the aux connector
>> (p.a.l. version European motherboard) so I think if one needs separate
>> vsync and hsync they have to be made by a circuit like the LM1881.
>>
>> The CGA monitor I have is an IBM 5153 and it is definitely a digital
>> monitor. The colors come out just nicely, but I can't synchronize, the
>> picture rolls. With the LM1881 I could get it to hold the picture only if
>> I enlarged the vertical so that 1/3 of the screen was not visible and
>> there was a noticeable gap between the lines. The LM1881 takes 5 to 12V
>> supply so I tried supplying both from the apple but there was no
>> significant difference.
>>
>> I will proceed later today to investigate with an oscilloscope and
>> compare the signals from the apple with the signals from the cga card. It
>> seems that the cga monitor is a good choice if I only can get it to sync.
>>
>> The other monitor, the Mitsubishi is an analog monitor but not a
>> multisync... it should work with an adaptation like the one suggested by
>> Marco Orlandi. It should according to the marking on the back be able to
>> use a composite sync. I have made a setup for 8 colors though intending
>> to use Marco Orlandi's setup to generate 16 colors. But it won't sync
>> neither with the sync signal from the RGB card, nor with the regenerated
>> one of the LM1881.
>>
>> So I hope the oscilloscope helps me to understand this better.
>
> Again replying to my own post, sorry...
>
> I have now looked at the signals with an oscilloscope and can find nothing
> wrong. I think my problem is that the Apple's output is interlaced, so the
> signal is unsuitable for the IBM 5153. I get the colors and horizontal
> sync ok but the picture rolls. The IBM 5153 even makes a noise back into
> the LM1881.
>
> The Mitsubishi HF2400 now syncs to the vertical, with the cleaned
> composite sync generated from the LM1881 but horizontally it is completely
> wrong. It seems to do 2 lines after each other per line and loosing one
> before the next. This happens whatever I do. I have tried to adjust a lot
> but it seems that the line from the apple is just too short. I think this
> monitor was used in a 1024 by 768 setup so it might be that the line
> generated from the Apple is just too short or something to that effect.
> BTW I could get this monitor to do sync on green there was a switch
> accessible with the cover removed.
>
> So, for now, I give up. I will see if I can get hold of a suitable monitor
> that was meant for the Apple. Analog or digital. If I get hold of an
> analog Applecolor GS type monitor I will use Marco Orlandi's setup for the
> RGB and the LM1881 to boost the sync.
>
> It is a pity that CGA monitor wouldn't work, the colors were nice, 80
> columns text were very readable, I just needed it to not to roll.
>
> It is possible that I can study the RGB card and make some schematics, how
> digital RGB is generated from the aux port. I'm interested to see if it
> had been fairly easy to make this extension (piggyback etc.).
>
> Knut
Knut,

I would like to discuss RGB Card schematic with you directly. Please
e-mail me using bparkoff@xxxxxxxxxxxxxxxxxxxx Remove "voy" and "abc" from
this e-mail address.
Please remember that Apple IIgs' analog RGB monitor will not work with
Apple //e RG Card when Michael M. claims, but it has to use resistance
network. The color information may not be correct. I suspect that it will
show only 8 colors instead of 16 colors.
Why do you claim that CGA is 1024x768 resolution? It is too limited so
I suspect that it supports up to 640x480 resolution. What do you think?

Bryan Parkoff


.

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