Improving signal strength on Superboard II

[ronin47]

Ha similar. Was always in software and got back into electronics fixing all these retro machines. Now I need a bigger house to support my “problem”.

Never knew about OSI til my friend gave me his Superboard II. I guess it’s kindof rare and valuable.

I need to find some more games and programs so I can make it do more than hello world loops.

I’ve got to brush up on my basic and figure out how to do graphics on it. But this portable project will keep me busy for a while.

TBH I'd never heard of it until I randomly saw a post on Stardot, the BBC computer forum, and somebody was asking if anyone was interested in 600D Klyball remake PCBs. I dove in and here I am, and now have a 610 from the same person.

I did recently find out that a variant was sold in the UK called the UK-101, which I had heard of, but until now I had no idea the two were essentially the same thing.

Need to get my cassette interface working before I can do much else.

[Sideburn]

My cassette interface didn’t work either. But it was just the previous owner had made so many mods I didn’t know what was going on. I basically had to undo everything to stock. But I spend a lot of hours wrestling with it and figuring out how it works.

[ronin47]

My cassette interface didn’t work either. But it was just the previous owner had made so many mods I didn’t know what was going on. I basically had to undo everything to stock. But I spend a lot of hours wrestling with it and figuring out how it works.

Going to work on it over the weekend, I've got the service manual, hoping that will help along with my oscilloscope.

[Sideburn]

Did you see my other thread on troubleshooting my cassette interface?

Maybe some clues in there : viewtopic.php?f=3&t=862

What’s it not doing? Mine had audio but the frequencies were off and I had to get the clocks right. I think it had been modded for higher baud rate or maybe for external floppy drive or something like that.

[ronin47]

Did you see my other thread on troubleshooting my cassette interface?

Maybe some clues in there : viewtopic.php?f=3&t=862

What’s it not doing? Mine had audio but the frequencies were off and I had to get the clocks right. I think it had been modded for higher baud rate or maybe for external floppy drive or something like that.

Thanks, I'll have a look later.

What's it not doing, well I set the jumpers for cassette usage and I see a signal coming into U64 on pins 2,4 and 16. The clocks also look good.

However on pin 11 all I see is a 1.2KHz signal, I tried a different 74LS76, but no tones when I save (On my scope) at either Pin 7 of J2 or Pin 9. I see a signal on the input side of R56, but not on the output. I lifted the cap, C13, but no real difference.

I also see data leaving the 6850.

I need to work back through the schematic/service manual tests and check if I'm missing something.

[bxdanny]

Sideview,

That does look good, the monitor seems to be the same width as the keyboard. But the last (48th) character seems to have its right edge cut off, and as there is more than one character width of blank margin on the left, you might want to decrease the value at $FFE0 by one [more].

When you mentioned wanting to add a speaker, I thought (I guess because I had just seen dave's comments to nama about sound from his keyboard) that perhaps you might also want to be able to play the "noise" output from J4. But since you don't have that section populated (it usually wasn't on the 600B), I guess there'd be no point, especially since it takes careful machine-language programming to make that sound like anything other than, well, noise.

[Sideburn]

Ok I still need to do the eprom edits. I haven’t done that with this setup. I think it was mentioned before you can’t edit in the gxpro program. I have the same software. I guess I just read the eprom and then copy paste into an editor.

[ronin47]

Sideview,

That does look good, the monitor seems to be the same width as the keyboard. But the last (48th) character seems to have its right edge cut off, and as there is more than one character width of blank margin on the left, you might want to decrease the value at $FFE0 by one [more].

When you mentioned wanting to add a speaker, I thought (I guess because I had just seen dave's comments to nama about sound from his keyboard) that perhaps you might also want to be able to play the "noise" output from J4. But since you don't have that section populated (it usually wasn't on the 600B), I guess there'd be no point, especially since it takes careful machine-language programming to make that sound like anything other than, well, noise.

@bxdanny If you're referring to my post, then yes there is a mild cutoff since I changed $7E0 to 64 from 65, but it is workable, however if I change it to 63 it goes off the left. I will check my work tomorrow but I think that was the case.

[bxdanny]

No, I was referring to Sideburn's picture of his board with his new, working monitor. Sometimes bad luck (like the broken screen on the first monitor he ordered) is followed by good luck (like his results with the new one). That's something I need to keep in mind right now (about other matters I won't discuss here).

[Sideburn]

Yes love when that happens.. happy accidents and "meant to be" situations...


** I just now got an email with a full refund... so the cracked monitor only cost me $6.00 (shipping it back).