This TRS-80 Color Computer is dead, so let's fix it

Earlier this summer I acquired one of these. Mine appears to be in fairly decent condition but I have not tested it. I have however uploaded a video about it but you don't have to watch it. In fact I have a lot of vintage computer stuff on my channel but my channel basically just sucks. Anyway it's always fun to try to get the stuff to work

The mod is a bad job, all those wires and extra components should be neatly under the board.

I'm about a year late to the party here, but got a second hand Coco yesterday - have you done a video on making the composite mod?

says pin 36 is NC....... sooooo

FYI, a less-risky way to remove those delicate flat-flex ribbon cables from their sockets is to cut a piece of thin flat plastic (such as from one of those overhead projector overlay sheets) to the same width as the cable, and then insert it between the cable and the socket pins before pulling the whole thing out. The same procedure can be done in reverse to re-insert the cable later while putting a minimum amount of stress on the contacts.

Hitachi makes a CMOS replacement Chip pin compatible with 6809e that are much better than the original they also make a chip for the coco3

Adrian... Where is the clip of the CoCo 1 running Popeye? I really wanted to see that.

Ram chip: Gonna process some data today... but then I went high.

Nothing better than starting a new series with Adrian with a cup of coffee and a chocolate cake.

What a great video! I’ve been catching up on your content and am really enjoying it! This video encouraged me to dig my old CoCo3 out of storage and hook it up again. So many fond memories! Sadly, I discovered we have a no video situation. I wish I had your troubleshooting skills. Greetings from Indiana!

Hi Adrian, can you tell me the model of your desoldering gun you are using because i would like to get my self one?

I used the color computers as machine very inexpensive controllers.
You could write a program in basic, do a few peaks and pokes, and gosub to transfer control to a plug in like a cartridge, that would run at full machine speed while in the subroutine. It wasn't hard to put a few 6522's and isolators on the external board to make it do whatever you wanted it to, and the pass the resultant data back to the basic program before you executed the return from subroutine and use basic to do all the graphs and calculations needed for the next gosub.
My friends all had Kaypros at work and would laugh at me for using the color computer, but they had no idea of the difference between REAL TIME DATA CAPTURES, AND SOFTWARE DATA CAPTURES, and were never able to get them to do much outside of the Kaypro box.
My only regret was that Radio Shack never came out with an 80 column version of it, and I had no access to enough information to make the changes to the basic roms that were in the machine to make that happen. I think that if they would have done that it might have cut into their TRS 80 sales, so it was probably a marketing decision.
Dennis O.

A common warning with using the CoCo was to turn it off before inserting or removing a cartridge, because there's a high risk of frying the CPU. It looks like that that's what happened.

There is too much PSU components on the motherboard. In the Dragon this is a separate board. Also has an external AC output PSU. You don't want mains inside your computer. APC ATX do do this but the PSU is s sealed unit.

Expensive looking ceramic DRAM chips.

So this is quite a heavily modified CoCo. It's actually pretty cool, I'd like to see the mods retained rather than returned to standard.

I'm still waiting for the prize you told me I won. Let me know if you need more giftcards to cover shipping.

Thanks!






JK

Bought a COCO when it first came out and took it back 2 days later. It was IMHO junk.

Awesome video! Being able to follow you and follow your logic is a great learning experience. Thanks for the content!

This is a good video, I really enjoy all your videos. I want to buy another Commodore, but man, they cost way too much one eBay. I am wheelchair bound, and therefore, not too much funds.

These videos are so cathartic, Adrian. It's like calming electronics ASMR.

Anyway you could do a video where you network TRS 80 commodore 64 Atari 400 and a Macintosh computer

You could buy the tech manuals at the stores. I had one for my Model I.

Standard, off-the-shelf, 7400 chip is bespoke? that doesn't make sense to me.

who the creator btw, are you impersonating the Lord

The two people that got me into electronics and computing were the one's that designed and made that keyboard upgrade kit for the COCO I. They gave me their old stuff once they moved on so I had tons to play with.

That 6809 was probably the most powerful 8 bit processor around, being 16 bits for a lot of the internals, but the 8086 came out about the same time which was a real 16 bit. All of the instruction set features, especially the 5 (?) addressing modes went directly into the 68000 line.

I also got an operating system called OS9 that was virtually a clone of UNIX. I later did some programming on a real mainframe UNIX system and really couldn't find a difference. It was a Multiuser/multitasking system. I once used a PC as a terminal operating a 80 char wide word processor at the same time I used a 64 char wide setting of the same program at the same time on the COCO II. The operating system actually used a single copy of the program in memory with the users totally isolated.

Because of UNIX's ability to load drivers (windows stole the idea) I was able to hook up a SCSI hard drive.

I loved my COCO.

Nice!
Just a small critique, it's a bit hard to follow which video is next in a "series", it requires some archaeology and clicking on different videos to get the next one.
I'm still uncertain as to which one is the next in this "series".
Maybe i'm just dumb, but i'm usually not.

They used the 6809 in the Space Shuttle, so they were deemed rather dependable.

I never realized how much of a tech nerd I was until I started seeing these videos and knowing what you were talking about and understanding the repairs/problems, reminds me of repairing my pre-historic IBM 386 at 9 years old with an instruction manual in German.

"Human Malware" I haven't heard that yet 😀

Back in the early 70’s I helped my dad build SWTP computer, from there we did mods on the COCOs. Eventually he built his own machines based on the 6800/68000 called ACORN. Let me know it you have run across one. I might be able to share on. I have the ML AC, logic, board designs and schematics!

Hell yeah man good work

I can remember back in the day I had an IBM PC, and a friend at work had a CoCo. Many of the young EE's at my employer had 'PC's because it had implemented a very generous loan program to buy them. We used to sneer at the Radio Shack computers. I had brought mine into work to do spread sheet and word processor work on it, but was showing off some game that played the William Tell Overture. "That's nothing" one of my office mates said, I'll bring in my CoCo tomorrow and show you what real computer sound is like. He did and blew my stock PC sound away.

How is the composite video being displayed in a window on Windows?

I love your SepTandy. Please keep it up. I worked for Radio shack back in the 80's. My first computer was the TRS-80 Model 1. I still have it. I also have an original Coco, a Model 4P, various pocket computers, etc. Love your channel.

I'm surprised you didn't do some simple voltage checks to verify everything needed was there.

The games looked better than I expected. The cave game "Download" looked pretty good. Will be interesting to see the Dragon. In the UK I knew a couple of people who had a Dragon back in the mid 80's (one being a school teacher). I think the graphics chip in the coco and the dragon are the same as in the Acorn Atom computer.

"Human Malware" LOL... very good side stepping Adrian... Get well soon mate...

Adrian's videos are like a master class. nice job.

Please try to remember, this was before the internet. You had to pay Radio Shock an extortionist amount of mullah for those technicians books.

I just found your channel and have been binge watching, I just got over the "Human malware" myself

I wonder if that cartridge expander could have killed those chips.

I like your rigorous diagnostic technique Sir. Interesting that the two main engines in the machine were faulty.

Trash-80!! Used to have one these. Awesome! 😃

May I recommend trying Moon Cresta, Rommel 3D, Phantom Slayer, Grabber, Color Car Action, Lunar Rover Patrol, Qiks, Ice Castles, Galagon, Tut's Tomb, and Time Bandit? Some of those require 32K of RAM, and you've got 64K so you're good. Hmmm.... Marble Maze and Gantelet will run on there too.

In old times I had the impression that some chips tend to destroy each other. But with today's knowledge I'd rather question that. Does somebody have better information?