Rastamafugg

@rietveld Thanks! Looks like my guess at the serial number meaning was wrong about the year. I'll have to take a look at the dates on the chips when I open it up for some maintenance to figure out when mine was made. That's an impressive Coco collection! You've got a lot of interesting peripherals hiding in the corners of those pics, too. And a good collection of Ataris and other systems off to the side! That first picture is pretty much my first two computers growing up. Radio Shack was right next to the arcade in the mall, so I spent a lot of time there when my mom or dad went shopping.

I know this is a long-dormant topic, but did anyone ever try to replace the 6809 in the Vectrex with a 6309? I'm going to be opening mine up to apply the buzz kit when it arrives, so I was thinking of doing the swap at the same time, but I was hoping someone has tried it out before and posted their results.

Maybe I'm having a bad googling day, but I can't find a list of serial numbers for the Coleco Adam (Or Colecovision, for that matter, although I found an old forum link to a defunct Colecovision serial database). Is there one out there somewhere that I'm just not finding, or even an explanation of the number sequence? Mine is A8102735. I expect A represents the factory and 81 might be the year of manufacture, meaning mine is the 2735 unit made in late 81, possibly? That seems early, chronologically, though.

I located some assembly books for the coco. I think what I'm looking for is registering an interrupt handler for IRQ, which fires 60 times a second. If I'm reading that correctly, though, does that mean the IRQ interrupt fires at the same point in the display cycle? And is that predictable? (eg: start of the vertical blank?) I'll try asking some of the sources Michael linked to above, as well.

Is there a good source for code examples using the various interrupts available for the Coco? Preferably Basic09/Nitros9 examples, but I'm having trouble finding anything online other than what is documented in the service manual documentation. I'm particularly interested in inserting code to run when the HSYNC and VSYNC interrupts trigger, but I can't seem to find any examples or tutorials for Coco interrupt handling in general.

I found this line in the readme interesting: I'm curious to see how that queue was implemented. If the communication was via the joystick port, I wonder what the cassette port was used for?

To answer your question, if I'm correct, the unit was only on sale for a few months before it was discontinued (Sept-Nov 83?). Anything cancelled that quickly must have sold really poorly (although video game crash of 83 certainly helped). Most units that are out there were probably bought on discount after it was discontinued, so I would guess the number of units out in the wild would be in the low thousands (maybe even high hundreds). Nothing but a not-so-educated guess on my part though. ?

If you ever wanted to part with one, I'd love to add one to my collection! It would be interesting to put an oscilloscope or a logic probe on a working system!

Good points, thanks! Your YouTube videos on the MBX were the primary inspiration for the question. I didn't realize the machine hasn't been fully documented yet. That would have to be done first, for sure, and would require original hardware to help reverse engineer the system. I wonder how good MB's internal documentation for the system was? Although it sounds, then, that not even schematics survived the decades. I grew up with an MC-10 and Coco 2 at home, so I'm more familiar with the 6809 in that context. I used a few Ti99's growing up briefly, but I'm pretty much starting from scratch learning the system itself. I'm curious about that serial communication between the two systems. It uses both the joystick port and cassette port to communicate, which seems like a weird choice when the side port was there. Someone with some serious hardware hacking skills must have come up with that solution! Does that mean it only sends input data back to the Ti99? Any sounds/speech it generates come out of its speaker (although, if it's connected to the cassette port, I wonder why they didn't try to push an analog audio source through there?), and I assume the voice recognition would work by converting the voice command onboard and sending the relevant joystick/touchpad command to the Ti99. On a side note, is/are the original designer(s) of the MBX known? If they were still around, that would make a fascinating interview!

Has anyone tried to make a reproduction of the MBX as a whole? I've seen some joysticks built from new parts, but I was wondering if the the main box is reproducible in 2022? I couldn't find any attempts documented online through my searching. I know the heart of it is a 6809 processor, and it relies on the Ti99 for video and some of the game sounds (other than what it drives out its own speaker). Are there any custom chips that can't be sourced today? I don't see why the touchpad, joysticks, and mic interfaces couldn't all be replicated. I love obscure hardware add-ons for old computers, and this is one of the weirdest I've seen. Shame it's so rare.

Yeah, that's what happens when you are retro-browsing in two different playgrounds! Meant to post this in the Tandy group! I also just picked up a FinalGrom99 and was doing some Ti99 deep diving and mis-posted!

I recently picked up a Model III that needs some TLC (a mouse made a bed under the floppies and the power cable was cut). I want to also replace the RIFA caps on the two power supplies in the machine. When I read tutorials online, like this one, they indicate there should be 3 caps to replace. This is a picture of the floppy power supply in my machine (the two are identical). I only see the larger RIFA cap, and the layout of the board is quite different from the ones I found online. Maybe a later revision? Do I just need to replace the one RIFA cap on each board?

Now it's not powering on at all. ? I'm wondering if there is a cold solder joint or something only loosely connected. Going to have to go over the board with a magnifying glass, I think. I have a bench power supply arriving on Friday. Providing I solve this issue, where do I connect on the board to provide +5V to the system main logic and bypass the power circuit (as you mentioned in a previous post)?

?

The last set of voltages I posted were with the original Atari PSU. The PSU I've been using with the Dragonfly is a Berls adjustable PSU set to 9v DC. When the 7800 stops powering on, it doesn't matter which power supply I use, the light doesn't come on. What is freezer spray? Is there a particular product I should be looking for? As for a bench power supply, can anyone recommend a good one for retro computer testing?

So I read with the original PSU: At the bead powered off: 12.4-12.7v At the bead powered on: 10.4v At the right most leg of the 7805: 10v It won't stay powered on long, though, with the original PSU. It powered off while testing and won't turn on again.

Ok, didn't understand you wanted me to test with the adapter connected but 7800 powered off. Here are the readings from that bead: 12.75v original psu off 8.94v dragonfly pass-through off She doesn't want to start again, so any powered tests will have to wait until morning.

Measured the end of the ferrite bead closest to the big cap... Powered off: 2.37v Powered on (9v dc via a brand new power supply through my Dragonfly cart using the pass-through power connector): ~8.5v Powered on with the original 7800 power supply: ~10.2v

Here's another symptom... At some point during testing, the 7800 stops powering on. If I leave it for some time (hours at least), it start powering on again. Don't understand why that is happening.

I have Combat, and I'm pretty sure it was in color, but I can test it again.

Is this the bead you are talking about?

Missing apparently. Could that be causing the problem? The red plastic is stuck to the board, I believe. I'll take the plastic cartridge slot off and take a picture.

I also picked up a logic probe. Are there any tests I could do with that that might help troubleshoot the issue? First time using one, for me.

I tested with the back of the board facing me and tested the 7805. I got ~4.96v in the left pin and ~7.66v on the right pin. Are you sure those values are supposed to be reversed?

Here's a picture of the complete board. There is a resistor connected to one of the Sony chip's legs