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Msi 6800

Chuck(G) said:
The DTR pin is is pretty much standard for terminals (DTE), which generally is used to indicate to communication equipment (DCE) that there is a powered-up terminal present. Some modems, will not talk to a device not signaling DTR. DSR corresponds to the DTE signalling that it's present.

Here's a great tutorial on RS232 signalling.

There's no reason that the CT1024 can't talk to your MSI box--you may just have to slow things down a bit--2400 bps would be more appropriate for the time period.
Click to expand...

Thanks Chuck. I can slow the MSI down to 110, which is the speed my CT1024 is fixed at. But I get absolutely nothing when I connect the two. Now.. I don't have a male to male db25 null modem.. i have a male to female db25 to db9 and I'm trying to use jumper wires to go fr the db9 to the female db25 on the ct1024. I connect ground and tx and rx.. but there is no reaction at all from the terminal when the msi is switched on.
 
Make sure that the Rx and Tx lines are appropriately set up. Your CT1024 is certainly DTE, but your MSI box may also be setup as DTE, in which case you'll have to "cross" the Rx and Tx connections.
 
Definitely worth getting an RS232 break out box, will monitor the signals, sent test messages etc, really useful.
 
If you're on the cheap, one of the RS232 LED boxes is the next best thing:

mini-rs232-tester-db25.jpg
 
I'm beginning to think this WEEBUG is named such for a reason. It appears to have no other commands than the G command for loading programs (lets you enter 4 digits after you press it). Almost all other keys do nothing
.. except E which, once entered.. you cant do anything. D produces that string you see in my photo. I've tried other MIKBUG commands but no dice. Apparently Peter Stark may still offer his HUMMBUG ROM for $45.. that might be a better option.

I note this unit probably doesn't have its original 6800 cpu.. it has a 68B00 from 1980.

With the floppy card in.. it keeps asking for a system disk
Only way out of that is to hit the NMI button which returns you to the monitor.

I guess maybe WEEBUG was designed minimalist to keep memory free? I'm looking around for any dumps of the MSIBUG roms that should be in there but thus far no luck.
 
Learning a bit more here.

WEEBUG is not all that like MIKBUG/SWTBUG/etcBUG after all. Some of the keys are completely different. And some I thought weren't working, in fact just had a delay factor.

If I hit C, it brings up an error about /CLK68 driver.
If I hit U, it brings up an error about /UTILITY driver.
T brings up /TAPE.IO driver error.

E still freezes it for some reason.

I'm assuming the disk drive would be required to load the appropriate drivers... not sure how else they'd get in there. Anyway -- interesting stuff.
 
Okay.. it gets even more interesting. D changes the prompt from WEEBUG to 'DIXIE'... all kinds of little treats in this ROM. More later on what 'DIXIE' does.
 
Heh... apparently HUMBUG is involved here somewhere.. if you hit H, it gives you a HUMBUG driver error.
 
=falter;414143. It appears to have no other commands than the G command for loading programs (lets you enter 4 digits after you press it). Almost all other keys do nothing
Click to expand...

Hm. That sounds like an early form of the CNC programming language G-Code:
- https://en.wikipedia.org/wiki/G-code

On some advanced systems I worked on (Like Delta-Tau) the numbers actually mapped to file names. Those files contained the code to do what the G-Code stood for. This let you customize the commands, or add new ones.
 
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Well, I think SWTPC uses G XXXX to start a program at XXXX location in memory. I think that might be the function it has there. My understanding is all the 'BUGs' followed the same MIKBUG basics for the most part for interoperability, and usually any changes were to enhance. That said, maybe Weebug is, as I thought, a stripped down BUG that just has the basics to get the machine booted. It demands a boot disk on startup. What I'm not sure about is why the monitor relies on a driver to carry out certain functions. I'm guessing I'd need whatever boot disc this thing is expecting. And I imagine the odds of finding that are slim to none.

I did try a whole slew of random commands with this 'DIXIE' prompt, but it would not accept any, throwing up an Error 0. The only time I got a different error (E) was when I put a / in front of whatever command I tried to give it. I did a search and there no info on a 'DIXIE' anywhere. Dead end again!
 
Cable makes a difference. With a proper DB-25 to DB-25 null modem I hooked the MSI up to my CT-82 and it works like a charm. Even beeps like it's supposed to. Nice.

Doesn't work so well on the CT1024. Baud rate is correct but it mostly produces ? marks with the occasional intelligible letter. I'm guessing it has to do with the format of the data.
 
I think that's exactly it -- the CT1024 is set up for 7 bits, 1 stop bit, even parity. The CT82 is 8 bits, 1 stop bit, no parity.

If it didn't involve desoldering I'd probably change it. But I'm hoping to pair my CT1024 with a real SWTPC 6800 and I suppose it's best to wait to see what config that has before doing that.
 
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