[Coco] Program for test pattern for crt alignment/convergence?

[Mike Delyea]

You may have an issue with the sync when hooking up to a coco III.  I did
this many years ago and I remember I had to create a little circuit with a
74ls flip flop to invert the sync.  I posted the instructions along with a
crude diagram on one of the coco sites that is now defunct.  Maybe its
archived somewhere.

On Mon, Aug 8, 2022 at 2:15 PM Eric Canales via Coco <coco at maltedmedia.com>
wrote:

> I wouldn't use a coco calibration tool. The issue with the CoCo is it's not
> particularly designed to give you an accurate picture and resolution that
> fills the entire tube.
>
> What I'd suggest is instead hook up a nice DVD player to the monitor, and
> then use a standard calibration DVD to generate the patterns. Spears &
> Munsil is quite good:
>
>
> https://www.amazon.com/Spears-Munsil-High-Definition-Benchmark-Blu-ray/dp/B0
> 0UGQ8GEU/ref=tmm_dvd_swatch_0?_encoding=UTF8&qid=1659982222&sr=8-1
> <https://www.amazon.com/Spears-Munsil-High-Definition-Benchmark-Blu-ray/dp/B00UGQ8GEU/ref=tmm_dvd_swatch_0?_encoding=UTF8&qid=1659982222&sr=8-1>
>
> Make sure to get the DVD version if you're using composite, or get the
> bluray if your bluray player has a good composite out. If you try to
> downconvert and HD signal you'll also be calibrating for your down
> converter, which tbh probably wouldn't be a big deal for use with the CoCo.
>
> One day I want to make a calibration tool for the CoCo but it's going to
> require quite a bit of testing, trying out various models of monitors and
> CoCos, and it's just much simpler to use a DVD player which is made to give
> you the most accurate picture it can.
>
> -----Original Message-----
> From: Coco <coco-bounces at maltedmedia.com> On Behalf Of Don Barber via Coco
> Sent: Monday, August 8, 2022 11:28 AM
> To: coco at maltedmedia.com
> Cc: Don Barber <don at dgb3.net>
> Subject: [Coco] Program for test pattern for crt alignment/convergence?
>
> Hi folks, acknowledge I'm sending a lot to the list recently but I got a
> lot
> of projects going on.
>
> I'm replacing the tube of a Commodore 1084S-D1 when the old crt tube 'let
> the vacuum out.'
> I've got it aligned pretty close by eye but to get it exact I'd like a
> proper test pattern, like white-on-black grid lines to get it just right.
> I've already soldered up the cable to get this monitor working on the coco
> so was hoping to be able to generate such a test pattern from the coco.
>
> As such, anyone know of a coco program to generate decent test patterns,
> specifically a grid / cross-hatch pattern?
>
> I found Coco Color Bars (
>
> https://colorcomputerarchive.com/repo/Disks/Demos/Coco%20Color%20Bars%202020
> %20(Jason%20Reighard
> <https://colorcomputerarchive.com/repo/Disks/Demos/Coco%20Color%20Bars%202020%20(Jason%20Reighard>
> ).zip
> ) which is awesome - but still looking more for the grid test pattern.
> Figure I could probably whip something out in basic without much effort but
> thought maybe someone would know of an existing one?
>
> Alternatively I could probably get a CGA cable together to hook up this
> monitor to an early PC if someone has an early dos program to generate a
> test pattern.
>
> Don
>
>
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