Tandy Color Computer 3 - Triad 512K - Coco-SDC - SCART - OS9 Fun

[I am sorry that I haven't posted a video in a long time. I have had serious health issues and real-life problems.]
In this video, we do some retro-computing with an 1987 Tandy Color Computer 3, computer affectionately known as a CoCo 3.
The machine is upgraded to 512k, with a Triad Memory Upgrade:
www.frontiernet.net/~mmarlett...
If at some point get a Hakko Desoldering gun, I would risk a cap replacement, but for now, I will run it. Though, I should have checked for ripple.
The CocoSDC is shown:
Coco SDC www.cocowares.com/item.php?nom...
thezippsterzone.com/2020/06/2...
A custom FD-502 style case, which is 3D printable:
BrendaEM's FD-502 Case for Coco SDC: www.thingiverse.com/thing:488...
Xnaron's Case for CoCo SDC, which is easier to print: www.thingiverse.com/thing:159...
A SCART Cable is shown and tested, based Barry Nelson's article on Hackaday: hackaday.io/project/7366-coco...
A cable could be purchased from: Switcharoo Cable: www.cocowares.com/search.php?P...
Lastly, we have some Microware OS9 fun.
Some other helpful links:
Facebook NitrOS9 forum: / 1929079184021683
Color Computer Software/Info Archive: colorcomputerarchive.com/
NitrOS9: sourceforge.net/projects/nitr...
Peter Boyle's Ease of Use OS9 distribution: www.lcurtisboyle.com/nitros9/n...
CoCo 3 Stress Test: github.com/richard42/cocostress
Color Computer 3 Emulators: www.cocopedia.com/wiki/index....
Please support my projects by Patreon: / brendaem
And please watch some videos, to get this channel monetized.

[@CurtisBoyle]

Oh, forgot to mention about BASIC09 assigning 22 bytes for data when you have no DIM statements yet. That's a 22 byte block that every procedure gets to hold special flags, etc. for each procedure (this includes things like whether ON ERROR GOTO is enabled (and what line to go to), whether the program will be BASE 0 or 1, whether you are using Radians or Degrees, and a bunch of pointers local to the process (it's own stack, it's string stack, where it is in the program, etc.)

[@CarsandCats]

I am drinking hot cocoa while watch your CoCo video lol. I learned to program machine code on a OG silver CoCo that I piggybacked the RAM to 32k. Using a hex editor, I wrote some pretty cool stuff. I guess this was 1982 or so and was my beginning into computers.

[@BrendaEM]

I remember people piggybacking RAM. Oddly, I have only seen perhaps one silver CoCo in person. I had and want to get a CoCo 2, late model Korean (south, I hope)

[@CarsandCats]

@@BrendaEM After the 32k upgrade, I would type in games from Dragon User magazine for the 64k and trim them down until they would run. Great fun and challenging!

[@moviestudioland]

We need MORE Brenda videos 🙂

[@WalterGreenIII]

I have thought of putting +5vdc on the RGB connector of the CoCo3, you could also disconnect pin 2 from ground to make another usable pin on the connector. You could possibly send composite and +5vdc through the RGB connector, and have a switch hidden in back to switch it back to pin 2 as ground, pin 10 disconnected. Personally I would use pin 2 as +5vdc so that both power pins are together, and composite video on pin 10 since the horizontal sync and vertical sync are already a part of the composite signal and might have less cross-talk issues. After a short section of ribbon, the rest of the cable would be a with multiple shielded conductors, although ground and +5vdc don't need shielding, the rest should in my opinion be shielded from each other and the outside world for the cleanest signal.

[@BrendaEM]

I have seen a mod where some added a pin for 5V. I am of it. Yet, I need 5V to run the SCART box.

[@CoCoNutBob]

@@BrendaEM pin 6 is unused, as long as it doesn't need much current. Maybe something from the monitor end is better for power?

[@smtwo7047]

Thanks Brenda for a very informative video. I think your SDC case is brilliant! Since the SDC is a drive emulator, it only makes sense that the case should look like a classic drive controller. And the ease of access to get the SDC in or out with your vent plate is terrific - it completely negates the need for the ugly DIP switch hole I've seen in other 'sealed' cases (seriously, how often do people need to reset those switches?). I'll certainly be using your design for my SDC when I get one!

[@WalterGreenIII]

There is no replacement for the GIME chip. In fact no one knows exactly what is IN a GIME chip but someone is working to duplicate the functions of the GIME in a project called "GIME X" or maybe "X GIME", not sure of the exact name. However, if you are going to put 2 megabytes in a CoCo3 you need the "Protector". The purpose of the Protector if to supply protection to our aging 6809 / 6309 CPUs so that power and level fluctuations can not overload and damage the CPU. The second benefit is that the Protector sits in the CPU Socket and provides access to the signals needed for the 2 Meg upgrade. Since the CPU must be plucked from the CoCo to install the Protector, might as well add a 6309 to replace the 6809. The 6309 runs ALL 6809 code, but also can run in either 6809 or 6309 more. When using the full capabilities of the 6309, 6809 code still runs, but now you have access to additional machine language commands, and the machine can perform some functions in fewer clock cycles. Fewer clock cycles can mess some things up like if the software has to access hardware ports, and decreased clock cycles changes the speed the computer access hardware. The hardware might not be ready when the software is, as the software finished and is trying for another hardware access before the hardware can provide it. All of these new 6309 features speed up the machine even without changing the clock speed. Also if you do not mind readjusting and tweaking your monitor, you can run the 6309 at speeds closer to 3 megahertz, but again since this throws off the video timing signals you need a monitor that can handle that. Not sure the SCART adapter can. I have seen people speed up a CoCo3 clock speed to 4 megahertz, however this will stain the 6809 (but it has been done) and makes the 6309 work harder, which in the long run will also strain the 6309 more than running at 1 or 2 megahertz. Again speed increases to the CPU speed up all timing signals, and do strain the other chips as well. Changing speeds means the video signals are sped up and no longer work with an unmodified monitor. It is all possible, but it is a lot of work.

[@BrendaEM]

It seems that everyone has a GIME-X, but me. LOL! I had not thought about the monitor timing and the SCART box. Hmmm.

[@andynarain672]

Can you do a video showing how you build the RGB to SCART cable?

[@picturesalbum4532]

No you do not replace the gime chip to use 2 megs there is just a bit of extra circuits added around the CPU to extend the gime's original MMU from 6 to 8 bits the current way of doing this is with a special version of the Protector. I am not sure if this is needed if it is a GIME-X .

[@CurtisBoyle]

The original 128K RAM chips are 4464's - these are the chips (used in pairs) to upgrade later Coco 2's to 64K. So you now have two sets of those. :) Also, would love to have you download and install NitrOS-9/EOU, and see what you think of it.

[@BrendaEM]

I have used it. Thank you. I like the idea of EOU, but with only 512k, memory is a little tight. Before I bought the Triad, I looked for one of those 2MB upgrades, but didn't find any physical hardware for sale. You have some cool dynamic setup stuff in EoU, which I need to study more. Your Ease-of-Use project is great for the CoCo community! I included a link to it. I am aiming for a large-volume boot that's more minimal, and MV capable (all 15 window descripers.) that's still modern with DriveWire and SDC. [I remember that old Frank Hogg advertisement with 2 of Teac 1.2mb floppies. Someday I will afford them. I had 2 3-1/2 720's on the end of my old FD502.] BTW, commandgen rocks. A good addition for an OS9 system. You probably are aware of it, but it embeds a OS9 (assembly macro?) shell statement into an executable, and adds a CRC, so that one-line shell commands can be loaded into memory.

[@CurtisBoyle]

@@BrendaEM - You still have a fair bit of memory free in an EOU boot (300+K with 3 80 column windows running)... and you can modify the startup file to shrink it down a bit if you want (not preloading all the fonts, etc.). I do remember the shell command "wrapper", although I don't think we currently have it preinstalled on EOU. I still have a 3.5" on one of my Coco's, although I use the special FORMAT command (20 sectors per track vs. the normal 18) so that it has 800K or more per disk. Although I use the SDC in hard drive mode with two 128 MB VHD hard drives running by default.

[@BrendaEM]

@@CurtisBoyle , I will look at it again. Commandgen is on colorcomputerarchive.com, in one of the utility packages. When I next have the CoCo 3 on the table, I will find out which. There are some other great OS9 Utility packages on there. I also grabbed Scred from the development tools, to use as a text editor. It seems that everyone has a 2MB RAM upgrade but me. LOL! It's like they made a few of them and then stopped.

[@CurtisBoyle]

@@BrendaEM - Yes please - let me know which utility package CMDGEN is in, and I will add it to EOU. Was that originally part of the one of the Shellplus packages from back in the day? I can't remember. Also, SCRED is definitely pre-installed in EOU; I use it in 106 column mode all the time when editing wider line source code listings. (My other favourite is VED because it is quite powerful, small and fast). But we have lots of editors to choose from!

[@moviestudioland]

Hey Brenda - I sent a wifi router to you at Campbell Coffee Shop on April 10th 2023 to simply plug in and use at Campbell coffee shop. Hope you are doing OK

[@BrendaEM]

Sorry, but its out if my hands.

[@DonaldRichards-mr3lz]

Gently rub that smog with a pencil eraser , I have a Co-Co 3 and that is how I know a pencil eraser works .

[@CoCoNutBob]

That unused power cord knockout is apparently for 50Hz models, fyi. ✌️

[@BrendaEM]

After 35 years, I have my answer : ) Thanks!