[Coco] Using Roy's vga adapter with other computers
snhirsch at gmail.com
Sun Oct 25 09:09:49 EDT 2009
On Sun, 25 Oct 2009, Gene Heskett wrote:
>> Any hints on where to get parts for creating the cable needed?
> Keep in mind when srcing the parts, that the amiga's video connector is _not_
> a db25, but a db23.
The DB23F required for the computer end of the cable is rare, but there
are a few folks on the internet selling them.
> Also keep in mind that the agnus chip cannot drive all 5
> outputs and will shut down to protect itself if the H&V sync lines aren't
> buffered with external logic. All of the cables made back in its heyday
> actually had a cmos logic chip buried in the backshell plastic casting to not
> only buffer the synch signals but also combined them into whatever mode and
> polarity that monitor needed.
But, the Amiga connector supplies both H&V sync and composite on three
separate lines. Why would you need further munging?
> It being cd4000 family cmos stuff, wasn't all
> that happy driving a 75 ohm load, so the failure rate was a problem, I've had
> to cut it off and build a new one twice now. And I used the 74HC nand gate
> for that, much more robust.
Is that what's inside those silver HD15F --> DB23F adapters that were
provided with newer Amigas?
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