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Post by atarmiga on Jan 19, 2021 16:48:01 GMT
I received two Commodore 128's as a donation. I was unable to test them because I didn't have a monitor that took RGB. So I bought a cable off ebay so I could use RCA cables. So I hooked up the first one and it boots up with what looks like the initial welcome screen but it's blank... no READY or cursor. The second one boots up and appears to be working. So they both appear to be black/white and I'm not sure why. I input a small program that should have printed out in colors but it was still all black/white. So I thought maybe it was a bad cable, so I hooked my TI-99/4a up to it and the color is working fine though it. I am lost and was hoping someone here could give me some advice. I highly doubt neither C-128 has color.
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Post by gsteemso on Jan 20, 2021 17:35:02 GMT
There are a bunch of things that might be happening, here. First, which video-out port did you connect to? The round socket for VIC-II video is exactly the same on a 128 as it is on a C64, being old-style TV format; while the DE9 port for 80-column video is pretty close to standard CGA -- except that one of its 9 pins carries a black-and-white image of the 80-column screen formatted as - again - old-style TV.
Both video signals are active at all times, whenever the computer is powered on. You can select which one the 128 treats as "active" at bootup by the latching 40/80 key on the keyboard, and while it's running by issuing a "GRAPHIC {number, options}" command in BASIC 7.
It sounds to me like you've had both 128s hooked up only by their 80-column ports, with one of them not showing any text because it's booting up with the 40-column video "active" which you don't have anything connected to, and the other connected to the black-and-white TV-format signal instead of the RGBI signal in the 80-column-video cable.
Computers of that era and earlier were often built with similar video-out formats emitted from completely different cable sockets, and even when both socket and format were the same, quite often the pinouts weren't. (For example, nearly every Mac and every Mac monitor used to have a DA-15 video port, but the first ...maybe 8 or 9? models that had them were all wired up differently!)
In other words, even if it looks right, you can not always assume your cable is correct unless you have verified its pinouts yourself with an ohmmeter or continuity checker.
I know from my own machines that some Commodore monitors had a bunch of option-swapping switches to try and work around the problem. If yours has any, are they all set to the right positions?
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Post by atarmiga on Jan 20, 2021 19:41:13 GMT
I took a picture of the port I'm using and the only switch I see is one marked L-H. I am not using a Commodore monitor, I am using an HDTV with red, white and yellow RCA ports.
And the 40/80 key on the other one got the READY prompt up, thanks!
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Post by atarmiga on Jan 20, 2021 22:09:02 GMT
It's working now. Thanks
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