Tandy COCO 2 world premiere, garbage screen or IO ERROR

[guibrush]

Hi, thanks to Brendan Donahe, I have now the wold first PAL COCO 2 with a COCOVGA built in ?

https://imgur.com/krF75l3

Brendan build a custom board to relocate the COCOVGA, has the video chip on the PAL machine is under the keyboard. Works like a charm!

https://imgur.com/YD6wcn7

https://imgur.com/fDdGq5z

 

I have the excellent COCO SDC too, and I have now a working setup:

https://imgur.com/n4ZZ2Da

 

But I have a problem: many softwares that I try to launch give me one of those 2 errors: sometimes I have a IO error in 20, sometimes a screen full of garbage. I have only a few sotware that run fine, most of them present on the SD do one of those errors. I'm wondering if I do something false, or if I have something broken? I have a 64k ram expansion plugged, I tried without the board but then the computer won't display the basic prompt.

https://imgur.com/PatRoFO

https://imgur.com/0atxban

 

 

Thanks for your help!

[Michael Kline]

Hello,

 

Which titles are you trying to pull up? If you are using the image for the SDC from the colorcomputerarchive, then there are both CoCo 2 and CoCo 3 disks on it. If you're trying to run a CoCo 3 programme, the garbage image that you see on your CoCo 2 is due to attempting to run CoCo 3 programmes. The CoCo 3 will be able to read large files. Especially over 10 grans. 

 

File listings for CoCo 3 programmes, that are loaded on CoCo 2's, will show an exclamation point for all CoCo 3 commands.

[guibrush]

Thanks for your answer!

Yes, I'm using this image that I found on the colorcomputerarchive web page:

https://colorcomputerarchive.com/repo/Disks/Coco SDC/Image/

 

Somes examples of what I tried: Nos9L2 (in nitros9 drawer), 256SS.dsh (in demo drawer), airwolf.dsk (demo drawer), docodemo (demo drawer, give SN error in 4), BGdemo (io error in 20).

 

I browsed the game drawer but never was the exlamation point in the right column. So, all software that give me a garbage screen are for coco3, ok, thank you very much for the information. What about the other errors like SN error in 4 or io error in 20? 

 

I have 2 subsidiary question ?

- I tried some programs that should play some sound, like jukebox in music drawer, but I ear nothing. Is the sound suposed coming out from the little speaker that sits in the coco, or do I need another harware expansion ? Maybe the sound is not available with the cocovga?

 

- what is the idea behind the color check on some games? I had sometimes a question about a blue / red box, the system ask me if the box is blue (and of course it's not, it's red), and I found out that pushing a button on the cocovga change the colore scheme

 

I know tha'ts it's look noobish, but I never had a coco before ? Thank you very much for helping me!

 

 

[Michael Kline]

Ok, It sounds like you're trying to run CoCo 3 programmes on a CoCo 2. When you get a Syntax Error (?SN), LIST the line that has the error. For example; LIST 10 could show; "10 ! 40" which could be "10 WIDTH 40". The CoCo 2 does not know how to interpret CoCo 3 commands. So, it inserts an exclamation point for the unknown command.

 

Input/Output error can be a bad disk. However, I doubt that this is the issue in this case. If you do a DIR and the file size is like over 10, then it's a good chance the file is for the CoCo 3, that has 128K/512K/2MB RAM instead of 64K. So, you will get an ?I/O error. The exclamation point will not be in the directory. It will show up in a CoCo 3 programme, that is loaded from a CoCo 2, when you type LIST for a BASIC programme.

 

NitrOS9 is the upgraded version of the OS-9 Level I (CoCo 2) and Level II operating system for the CoCo 3. For the CoCo 2, Use NitrOS9 L1 (NOS9L1) or OS-9 from the L1V100, L1V101, L1V200, L1V201 drawer/folder. The path is: OS > OS-9 > and one of the aforementioned drawer/folders.

 

256SS.dsk is a NitrOS9 Level 2 disk. It will not load on a CoCo 2. COCODEMO is also for the CoCo3. I listed line 4, and the command that is giving the SN error in your case is: "ON BRK GOTO 610". It probably looks like: ON ! GOTO 610 to you.

 

I can't answer your question regarding sound. I don't have your video setup. I wish that I did

 

The video chipset has 2 different colour palettes. I forget the technical details. However, holding the reset button for a few seconds, perhaps several times until the colour set changes is required. It's an inherent design flaw, you could say. On the CoCo 3, holding down F1 during bootup, flips the colourset.

 

There are a few active CoCo users groups on Facebook. Although, I dumped FB this past summer. We're also on Discord. This link should get you on. https://discord.gg/4J5nHXm

 

You'll find a lot of knowledgeable people there, who are more than happy to assist you.

 

If you have anymore questions, feel free to ask.

 

Cheers!

Michael.

 

 

 

 

 

Edited October 31, 2020 by Michael Kline

[guibrush]

Thank you very much for all your answers!

So, looks like that all software that don't run are simply software for the COCO 3, make sense.

 

I found the right OS9 disk, thanks to your explanation. I understand now where I can see the exclamation point.

 

For the sound, I will investigate. But the COCO 2 have sound, right? On a normal COCO2 used with a RF TV, where do you get the sound ? In the TV or in the buzzer that is in the computer?

 

All ok for the video palettes, thanks.

 

I just connected to the discord, thanks ?

 

[Michael Kline]

Yes. The CoCo 2 has sound. It comes from the RF jack. The standard RF hookup outputs both video and sound. Just like Commodore, Atari and many other systems of the 80s and 90s. The stock computer doesn't have a built in speaker. It's all sent to the TV.

 

Cool. You're connected to group. Make yourself known. ☺

 

Cheers!