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

#trs-80 #repair #coco
On today's video, we have a repair of a TRS-80 Color Computer 1 -- something never featured before on the basement. The computer has a checkerboard pattern, so let's figure out why!
--- Video Links
SMMC 0035 where I unbox and do initial testing of this Coco 1:
• 0035 We have a broken ...
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-- Tools
Deoxit D5:
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store.caig.com/s.nl/it.A/id.16...
O-Ring Pick Set: (I use these to lift chips off boards)
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Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
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Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
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TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
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www.aliexpress.com/item/33000...
TS100 Soldering Iron:
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EEVBlog 121GW Multimeter:
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DSLogic Basic Logic Analyzer:
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Magnetic Screw Holder:
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Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
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Heat Sinks:
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Little squeezy bottles: (available elsewhere too)
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--- Links
My GitHub repository:
github.com/misterblack1?tab=r...
Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino

[@joaomarreiros4906]

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.

[@paulstein6563]

Really appreciate the variety on this channel. Seems like some retro channels are Commodore-centric, nothing against that line of computers, but I like hearing about Atari, TRS-80, Apple II, and early hobbyist computers as well. Thank you Adrian.

[@Doug_in_NC]

I totally agree. It’s the variety that really makes this channel one of the best (as well as the presentation of course).

[@XolaresTiberius]

It’s not surprising. Commodore and apple was more prevalent. Don’t know about my homeland Australia but I was PC and Amiga

[@Doug_in_NC]

@@XolaresTiberius c64s are pretty unreliable compared to say Apple or Atari which helps when you do repair videos too :-)

[@robinsutcliffe-video_art]

@@Doug_in_NC the presentation is second to none. The enthusiasm alone is worth the watch!

[@SonicBoone56]

Agreed

[@brentboswell1294]

A bit of CoCo trivia: the CoCo is based on the Tandy AgTerminal. A competition was held in the late 1970's amongst colleges to design a computer terminal for US farmers in the Midwest. It was supposed to dial into a central computer and supply the farmers with commodity prices, futures market information, weather forecasts and a mail system. An ultra rare Tandy AgTerminal looks just like a CoCo, with different ports (like no cartridge port), and an internal modem. Tandy won the bid to produce the competition winner (which was heavily based on Motorola 8 bit parts).

[@jwhite5008]

Interesting tidbit of info, thanks.

[@mickster150arcade]

My dad (a farmer) had one of those tandy terminals. My brother and I hoped to be able to use it as a computer, but were never able to make it do anything other than what it was designed for.

[@johnglielmi6428]

I remember that, Thanks for telling the viewership that sweet little tidbit about the beloved CoCo!!!

[@JoelReesonmars]

@@mickster150arcade It would have taken quite a bit of expansion, and a different ROM. For programming the different ROM, you'd have wanted another working computer.

[@Bob-1802]

I always wondered why Tandy didn't pick the Z80 to build the CoCo. Maybe the AgTerminal is an explanation. It would've been cheaper for Tandy, striving to lower costs, to use the cheaper Z80 already used in its Model 1/3/4 series than the 6809. Don't get me wrong, the 6809 is a great cpu, easy to program. The CoCo was in competition with other popular low cost 8-bit computers. Using the same BASIC and some softwares from Model 1/3/4 would have saved even more money.

[@sa3270]

It's always satisfying to see these old computers come back to life.

[@wayland7150]

In technical terms they are prehistoric. In personal terms I have a lot of skills associated with these machines. Simply firing up XRoar Dragin 32 I can immediately do things I struggle with on my Linux Mint PC. I've got a physical Dragon 32 (based on the same Motorola design) ready to run once I have a PSU. It will restore some of my computer skills once this runs.

[@aaronk2242]

There's a technique to more safely pull vintage flatflex cables out of their connectors, like on the keyboard you had here. Often, due to age, the spring contacts stick to the fingers on the flatflex, and it can tear off the metal. What you do is get a bit of thin stiff plastic, like the clear stuff from a blister pack product packaging, and cut it to the width of the connector. Then, on the contact finger side, you carefully slide it into the connector, maybe using a bit of deoxit as lube. This separates the spring contacts from the fingers on the flatflex, and you pull the flatflex out along with the plastic shim. No friction on the fingers means lower chance of damage.

[@SpearM3064]

Very useful tip, if I ever have to deal with that situation again. Thank you!

[@TuxraGamer]

That's some cool advice, I hae a few vintage machines to work on and this will surely come handy :).

[@kasamialt]

Recently been working with something that's not quite vintage but old enough to worry about, and it has a very stiff ribbon connector that has to be removed every time I want to disassemble the device. I'll be sure to do this next time.

[@TuxraGamer]

@@kasamialt if you take it apart frequently, it shouldn't be a big deal, this mostly applies to the case where oxidization causes the socket contacts to stick to the flex pins, increasing the probability of tearing the flex cable and/or ripping off the pins.

[@kasamialt]

@@TuxraGamer The socket is very tight in this case, maybe due to cheap parts or whatever, so I still worry about damaging the contacts on the cable or even tearing it from the force required. It's a fairly standard type so I could replace it if necessary but it's soldered down at the other end so would be a pain.

[@interactii]

As I recall it was pretty common on all these (1,2 and 3) for the CPU to fail if you pulled out a cart while the unit was on because the CPU pins to the cart connector are not buffered. I've fixed at least 4 units with dead CPUs like this.

[@drozcompany4132]

The CPU and the LS783 chip could go bad doing that. Learned from experience.

[@naysmith5272]

as James Bond would say "Positively Shocking". but seriously as a kid I would have pulled the cartridge at some point no matter how careful I would want to be.

[@GregScavezze]

Crazy that the engineers didn't account for people having a brain fart or kids that didn't know better.

[@wayland7150]

On the Dragon the 6809 is right up against the cartridge slot.

[@chryoko]

Thanks you very much Adrian. Always a great relaxing pleasure to watch your trouble-shooting videos. That Radio-Shack one is reminding me about my first computer shared with a good kid friend, a TRS-80 that was baught used in the south of France. We were programming it in Basic, then quickly in Z80 using the supplied editor-assembler. That was fantastic ! We had to learn English on to of Basic and Z80 programming. Then i went color with a VIC20, the Atari 800 was so great a dream, but over budget, and the 400 too bad with its film keyboard aka a ZX81. Realy pushed the VIC to its limits with the Floppy drive and some multi-cartridges extensions allowing for dumping those onto the extended RAM. I was programming in in 6502 directly in Hexacodes from a notebook to calculate the jumps, also exchanging programs on tapes via post all over Europe including behind the curtain (Poland). Then went the Amstrads CPC464 and 664 and later jumped to my first PCs build using a super powerfull 386SX16 .... Thanks again for yor chanel , i am sure that many kids of the time are watching every of your videos ;-)

[@ouethojlkjn]

That was wonderful you had to learn English to understand the manuals ! When we bought The Hobbit game for the Sinclair ZX Spectrum we had to read The Hobbit novel that was supplied to figure out how to get through parts of the game ! I hope like me, you turned a passion into a career ?!

[@dottedrhino]

This was fun! The vanilla TRS-80 was my first machine on age of 12. Get well soon! 🙂

[@johnelectric933]

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.

[@MattEnwright]

A note about the availability of the service documentation: In most cases they were available at the stores that had the repair centers sometimes for purchase, however if not, they could be obtained by what was called "RSU" (Radio Shack Unlimited) order, which was shipped from a warehouse , or via "Fax back". Fax back was a bit more limited, and was available later on... and was only for certain sections of the manuals if I recall properly.

[@peternichols3267]

I can attest to how durable the Color Computer 2's and 3's are. I was a Repair Technician for a regional Radio Shack repair center from 88-89, and CoCo repairs (except for 3's needing the ASIC socket cleaned) were pretty uncommon. I could also confirm that the documentation was readily available at that time via the Service Manuals that could be ordered at the retail store. It's pretty clear that the mod to the cartridge port was what damaged the CPU and the SAM. While hot-plugging wasn't good for a CoCo, it was tough to kill them that way. I'm looking forward to your Dragon64 repair video, as I am building one out from a bare PCB (yes, I have 4 "spares" if anyone is interested). It's a step in my project to clone a CoCo2 board. Eventually I'd like to see if I can add the bank switching and additional RAM that the CoCo3 does via a 6829MMU (the CoCo does that all in one custom chip). I'm capturing this via a personal website, which I won't post unless Adrian agrees.

[@johnhansen4794]

Thank you for drawing attention to the scammers.

[@benjaminvanderjagt]

Downland has a very fun-to-exploit bug. Some levels had jagged side walls, and it was possible to jump outside of the level through the jagged wall and progressively jump higher and higher until our hero is standing on top of the level. Jumping above the top of the screen sometimes caused our hero to become a "maker", where he left various random bits of reality behind him everywhere he went, even creating his own ropes to climb around on.

[@ouethojlkjn]

Sounds like Tron making an illegal exit from the game grid!!!

[@dbadilotti]

Thanks, this video was a walk down memory lane. Dad bought the Coco 1 (16k version/chiclet keyboard) as our first computer, back when it was pretty much brand new. Until you brought it up, I didn't remember Downland, but I recognized it when I saw it. I suspect that's because Dungeons of Daggorath and Quasar Commander occupied so much more of my time. Dad eventually did do the upgrade our to 64k (quite successfully), but never upgraded the keyboard. He was a hunt and peck typist and couldn't see what was wrong with it.

[@melanierhianna]

On some early CPUs it’s not good to leave them powered without a clock when not halted. Some early 6502s were like that. So may be the SAM failed which left the 6809 locked up and it failed because of the clock issues.

[@fedoralexandersteeman6672]

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.

[@antonnym214]

Nice investigation. I coded in Z-80 and 8080 Assembly back in the day, and as robust an instruction set as the Z-80 had, I was still envious of the 6809 16-bit multiply in hardware. Well done! Glad you're feeling better.

[@parrottm76262]

Wow, never expected those two chips to fail. AFAIK, they have a history of being long lived. So, "live" and learn. Great diag session. Loved it!

[@ftorresgamez]

My dad bought us a CoCo2 back in 1983 or 1984 (I don't remember exactly when) which had the melted keyboard. The first computer my dad bought for us kids was a VIC-20 which I loved to bits, but my dad didn't like it because the game cartridges were very expensive and the memory capacity was too low, so he sold the VIC-20 and bought us a CoCo2 with 64K memory from the local Radio Shack in Douglas AZ. At that time we were living in Agua Prieta, Mexico, which is a city just south of the border from Douglas AZ - I now live in Houston TX, so Howdy! I remember that the SAM (Synchronous Address Multiplexer) which coordinated so many things in the computer (DRAM refresh, video, etc.) got REALLY hot very fast and was a source of frustration for many CoCo owners because the SAM had the propensity of going bad. I am not sure because we're talking about 30 years now, but I believe some owners placed a heat sink (or two or three in a row) on top of the SAM to keep it reasonably cool.

[@Sashazur]

In college I had an original silver CoCo with the chiclet keys. It had the metal joysticks that tingled when touched! I replaced it with a CoCo 2 and did some assembly programming on it, wrote some utilities like a BASIC extension to display real lowercase, etc. It was a fun machine to learn on. I was a 6809 snob because it had more/better addressing modes than the 6502 and even the PDP-11 we were learning in class (though what did it really matter when all you had was 64K!)

[@psanangelo7326]

Our first computer was a CoCo 2, my dad bought it on sale. I think the 3's were coming out and he got the 2 for a good price. Thanks for bringing back memories for Father's Day weekend.

[@johnpetruna8888]

I got the Coco2 when I was a kid with the Chiclet keyboard, and imMEEDiately wanted to replace it. Kept an eye on the Coco press (Hot Coco & Rainbow magazines) and sure enough, the melted keyboard became a Radio Shack part number that could be ordered. I remember installing it myself, with no chip swap or bodges required. And yes, it was vastly better than the original for touch typing. Incidentally, the wear pattern suggests to me a two-finger-hunt-and-peck typist, resting their hands out of the way so they can find which key to strike.

[@Markus0021]

I was thinking the wear pattern might be indicative of someone resting their hands where the arrow keys could be accessed easily (far left and far right of the keyboard).

[@johnpetruna8888]

@@Markus0021 I saw a comment to that effect below. Not much of a gamer here, but that might be the better answer.

[@josephaltman460]

Grandma was using her TRS-80 to make '80s Rock Videos!!!

[@kjtroj]

Great basic diagnostic info! As for the keyboards, even if that melted keyboard isn't ideal, anything is better than the chiclet keyboard the original model has. Those things were stiff and awful to use, and made me strongly dislike the Coco when it was new.

[@wayland7150]

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.

[@deathproofpony]

This looks exactly like the TRS-80 we had when I was a kid. My dad installed the new keyboard, which made all the difference in the world compared to the horrible Chiclet keyboard. We also had an external floppy drive and a tape recorder. Great machine - we kept using it up to the late 80's.

[@jurgenreissing8209]

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.

[@wayneaaron5818]

Really like seeing the COCO getting some love.

[@MartinAlejandroLiguori]

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

[@timbald]

Adrian, a fabulous walk down memory lane. I had a UK PAL CoCo 1 in my teens - my first computer. Using the EDTASM+ cartridge and a 6809 book, and the excellent Tandy technical documentation, I taught myself 6809 Assembler. I used to poke a RAM location that switched the video page to &H0000 so I could watch what the machine was doing 'visually' on the screen in running the computer. I started writing 6809 code to produce a 7x5 pixel character set on the 256x192 resolution mode. I also wrote a 6809 program that listened to the tape port and basically listed on the screen what it found in each sound block from a CSAVE. I also (failed) to try and build a 8k RAM expansion for the cartridge port as the R/W line extends to the cartridge port - Tandy sold blank cartridge PCBs that you could mount your own chips on. I still have some Tandy reference material here somewhere. I recall a yellow manual called The Engineer's Handbook or similar that taught me so many of the TTL era digital electronic basics. Thanks so much. Really enjoyed this one.

[@ouethojlkjn]

You’ve just reminded me about creating my own character set ! It was for a Southwest technical products Corporation (SWTP) computer we had at work. I did not have the knowledge for machine code and wrote in basic various line drawing commands to create the characters.. it had the added effect of looking like a terminal running at around 300 baud. Ah, the miracle of youth!

[@topsyturvyy4558]

This is like operating on a living being, very interesting work you do Sir.

[@djdublo]

Another excellent video Adrian, thank you!

[@wintermute740]

My first home computer that I paid for myself was a Tandy CoCo 2, so the CoCo line holds a special place in my heart. Glad to see this one saved. I had two of these grey case ones back in the day, and they were in a box of computer stuff which went missing during a move.

[@mr.mrs.witowski29]

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

[@hoofie2002]

A great video that proves just how useful just a single channel scope is for troubleshooting.

[@snakefriesia6808]

i have a friend who's dad used to own a TRS-80 , gave that to my friend when he moved to the Commodore 64, and then gave my friend the commodore 64 when he moved to Atari St .. that kept the machines in the family for many many years, my friend became an Amiga Fan while i became an Atari St fan 🙂

[@Inadvisablescience]

I love this channel! I learn so many things I didn't know about these old computers. I feel so much smarter and if I ever get any of these computers again, I may just be able to fix them thanks to your channel. Hope to see the 4 cartridge selector up and running too. Thank you for your vids!

[@MickeyMousePark]

Working at Tandy Computer Repair center in the 1980s i think the Tech Ref was available for current models (models currently on the sales floor) in a softcover version (available in Tandy Computer Centers not regular Radio Shack Stores)..if my memory serves me they were very expensive around $30 ($80 2021 dollars) ..In my shop we had a 8 foot long shelf over the workbench with the Service Manuals (which would be different than a Tech Ref manual) 3 ring binders for every model..the unique thing about these manuals was on the schematics for every test point there was an image of what the o-scope signal looks like for that point..The manual also contained Tandy part numbers for every single part including screws etc..These were marked CONFIDENTIAL on each page so these would not have been available to the public.. A common user mod done on CoCo 1 in the 1980's was to remove the RAM badge on the case..under it there is a hole that perfectly fits a LED to work as a power indicator..

[@anotheruser9876]

The wear pattern on the case would suggest the previous user placed their hands to reach the cursor keys, probably a gamer.

[@granitepenguin]

I mentioned this on the second channel video, too. We also see clear evidence at 47:11 on this one :-)

[@HAGSLAB]

Great video, troubleshooting and result Adrian! I really enjoyed that.

[@MrLukealbanese]

What a fab fixing session. Thanks Adrian!!! 👍👍👍

[@AlanGrassia]

This was a good video and I really do enjoy learning about these computers while you are fixing them. Thank you.

[@8bitrocketstudios]

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

[@adamv242]

Thanks for some TRS-80 content! Really enjoyed this thorough diagnostic and repair session...

[@CyranoJones509]

To answer your question on service manuals, the manual you pictured on your computer was actually sold in store - as was the manual for the Mod I. Service manuals for the other computers and most other items in the store were available through special order from National Parts. Salesmakers might not have been aware of this. I found out through one of my customers at the time.

[@jstinn123]

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

[@JESUSCHRYSLER5512]

RIGHT SURE 🤡🤡🤡🤡. HE HAD ""TROUBLE"" PUTTING A BATTERY COVER BACK ON A SONY WATCHMAN. HIS VIDEOS ARE USELESS.

[@devttyUSB0]

Stay healthy, stay safe, Adrian! Really great fixing video!!

[@marekgorka894]

Hell yeah man good work

[@finished_it]

Really enjoyed the methodical approach to this fix, great video cheers!

[@blackterminal]

Interesting. Thank you.

[@50shadesofbeige88]

That was a very satisfying repair.

[@adriansdigitalbasement]

Thanks!

[@briannebeker2119]

The documentation for the Radio Shack computer where easily obtained from any Radio Shack for very reasonable price. I paid $19.95 for the model 1000 manual which was over a inch think and contained full schematics and theory of operation. A regular Radio Shack might have to special order it but the Computer Center stores typically had the manuals in stock. Radio Shack also carried data books for the TTL / CMOS logic chips. Back in the day Radio Shack was a great resource, that changed over the years as it slowly faded into obscurity.

[@adriansdigitalbasement]

This is just amazing. What an amazing company! I loved my local radio shack but I never even looked at the computers they had on offer.

[@briannebeker2119]

@@adriansdigitalbasement I never could afford to buy a computer in those days but I certainly wanted to learn everything I could about them. I ended acquiring a TRS-80 Model I & III years after they were outdated but I spent a lot of time building hardware to extend their capabilities. Watching your videos takes be back to my teens when computers where so simple and you could actually change things with moderately priced tools.

[@shadimurwi7170]

Wow you know something good job Sir

[@atlanticx100]

I had one of them. A great little machine .

[@brianlhughes]

It friggin works!

[@zepo82]

ribbon cables were the bane of my existence for a short time around 2000 . I stuffed up twice on my first day :P...I was used to normal pc's and was given laptops to fix..little did young me know how many ribbon cables could be possible back then - whoever thought they were a good idea needs binning :P

[@wazzym290]

Thank you for the information on scammers: I almost fell for it but stopped myself from reaching out

[@Wenlocktvdx]

I noticed the blue bean behind the cassette socket. It’s the cassette relay and this one is a reed type which was notorious for welding closed. Some replaced it with a regular relay. My sister and her boyfriend managed to kill my CPU, SAM and the 7404 in the disk controller by hot loading the disk controller. It can happen alright. The 6 bit DAC can generate 4 voices but no so much during gameplay as it took a lot of CPU work due to no hardware to assist it.

[@foogod4237]

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.

[@rod370]

Hi, Adrian. I liked the video. Thank you for making it.

[@MattOGormanSmith]

The model 1 Tech ref was certainly in the shops, but I didn't realise I could have had one for the Model 4 too. That must have been a special order.

[@KarlBate]

Get well Adrian.

[@grantfryer1]

It freak'n works! Good job.

[@RonHelton]

Nice work, Tech Lord!

[@charlesjmouse]

Another excellent video. Thanks. Yep, the CoCo 1 and Dragon are very similar machines indeed - both being based almost entirely off Motorola's reference design and both using the same M$ Basic - although why M$ supplied the exact same Basic to both companies but used different addressing is beyond me! Tips: 1) Most people would say the Dragon is a better made made machine, certainly a nicer keyboard. The Dragon 32 can be upgraded / modded to a 64. 2) The only practicable difference between the machines is the addressing of the M$ basic (why M$???) and the keyboard mapping. (Ok, I/O too) 3) While a lot of software and hardware will run with either machine it's a fairly straightforward job to mod either to be 100% compatible with both: a) Replace the ROM with a larger one containing both versions of Basic. b) A bit of wiring to allow the keyboard to behave like both machines. c) A switch to, um, switch between modes. So... Got a Dragon 32/64? Mod it to be CoCo 1 compatible - the CoCo does have a larger software library. Got a CoCo 1? Possibly modding one for D32/64 compatibility is less compelling, but I'd say fun anyway.

[@markevans2294]

Rumour is that Dragon Data made things like the keyboard mapping, BASIC tokenisation and addresses of various ROM routines different to avoid the lawyers. The Dragon 32 has a parallel printer port. Additionally, the Dragon 64 has a serial port. Allegedly some of the last Dragon 32s to be produced are the 64 in a 32 case. Possibly with the serial port unpopulated and/or the memory jumpered to 32k. (There are similar rumours that some ZX Spectrums shipped with fully working 4164 DRAMS.) There is a US version of the Dragon 64 called the "Tano Dragon".

[@rastislavzima]

Right on time, I wanted to watch something on youtube during saturday evening "siesta" but saw everything on all my followes channels, but here comes the Adrian, so lets go right to it!

[@orangeActiondotcom]

Downland colors toggled between blue and red (over RF, anyway), blue seems to be the desired color as things looked wrong in red. I hope you give it a shot with the Tandy deluxe joystick, it's definitely one of the better CoCo games!

[@fireball0762]

in middle school we had a trs-80 in one of the 8th grade math classrooms. The teacher showed me how to load in programs with a cassette player. Now days 8th graders wouldn't know how to use one of those computers

[@CarnorJast1138]

This was my first computer. I had the 4k version with the chiclet keyboard! I had it upgraded to 32k, but unfortunately there was no option at the time to switch out that horrible keyboard! I so loved that computer, and it led me to become a PC tech later in life. I did a lot of Basic programming on it as well as some really decent games! Dungeons of Daggorath was my favorite game on this system, and it was the precursor to 3D games we see now. This system led me to getting an Atari 800XL, then later the Atari 520ST. From there I went to the PC, building it myself, and was rocking a 286/12 with a VGA graphics card! Wooohoo!

[@therealjammit]

Radio Shack also had great documentation and schematics for pretty much all of the things they sold.

[@esra_erimez]

It amazes me how a 50 minute video can go so fast

[@RetroHackShack]

My first computer! I still use that model today to test my RGBTOHDMI boards.

[@frankowalker4662]

Nice fix.

[@horusfalcon]

NTSC = Never Twice Same Color! Good job on getting this old girl running. Hope you can find some more SAMs and CPUs.

[@jimparr01Utube]

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

[@naysmith5272]

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.

[@davefarquhar8230]

The first computer I ever used in school was a CoCo but I'm not sure if it was a Model 1 or 2. It was 1983 so either one was possible. So it was nice to see an early CoCo coming back to life here.

[@dougc314]

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.

[@alexgayer85]

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!

[@michaelturner4457]

47:15 Besides the Tandy CoCo and Dragon 32, the Acorn Atom and Vtech Laser 200 also have the same garish colours in graphics, as those computers have the Motorola MC6847 VDC chip.

[@ronostrenski8359]

Nice work. Very well presented. Regards Ron. Australia

[@williamharris8367]

The green @ symbol is ASCII 0, and the orange block is ASCII 255.

[@borgmoon]

I love your channel. I saw it in my TV using an Android TV Box, so is impossible to do comments to your video. While watching this video on my tv, I'm writing this on my PC. I had one of this CoCo, with chiclet keyboard and 16K RAM. First that CoCo had all chips in sockets. The 6809E CPU was a fairly easy chip to get. The Williams arcade games of the era used that chip. So if you new someone who repair those arcade games, could give you some used chips. The 6883 SAM Chip is another story. Is a custom made chip for these computers. And is almost impossible to find one in those days. I checked Jameco and other sellers of the era and no one had it. The 6821 is a regular chip and could be obtained easily. The 6822 is another custom made chip to handle the keyboard. The ROMs are the Color Basic and The Extended Color Basic. As you stated, both 6809 and 6883 chips are almost indestructible, but things happen. Specially because even with the computer turned off, there were power running in the board. So any mishap with all those cables could shorted both chips.

[@ItsaRomethingeveryday]

I had one of these as a teenager and it is not an easy system to navigate at all, the programming was long and had to save it onto a cassette tape, that was connected to trs80, as far as it's gaming capabilities the joysticks that were designed for it were fairly decent especially for the era

[@chrisschanneloftechnology4743]

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

[@TheStraycat74]

the TRS-80 Color Computer with tape deck was my first computer back when they model 3 was first introduced. I had an idea about a month ago to convert a TRS-CoCo to modern 2022 computer internals.

[@Dennis-mq6or]

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.

[@johnglielmi6428]

Finally a video for us CoCo lovers and supporters! next to my IBM PC Jr. the CoCo was my first home computer.

[@theJohnnyPinball]

A+ job

[@peteregan9750]

I did work experience at a TANDY store in the mid 80's - their list of technical books avaliable to buy was impressive .....

[@MattPlachecki]

Great video! I hope to see more CoCo content sometime soon! I have a CoCo 2 and would like to put it to use :)

[@Wenlocktvdx]

Thinking back my sisters boyfriend took out my 6809E and SAM (6883) by plugging in the disk controller with power on. She wouldn’t accept liability but said exactly what they did. I got the chips replaced but the disk controller wouldn’t boot. Yup, the 7404 used as an address decoder was dead. Never hotload a cartridge or anything else.

[@NEEC1]

Great stuff. Two chips down. Well done :)

[@tigheklory]

Great video! Looking forward to you doing a restoration on a Colecovm Adam computer! The forefather of the MSX!

[@Rx7man]

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

[@GameTechRefuge]

Take care Adrian. Hope your feeling better soon. Have to admit, I kinda like the video out, warts and all.

[@johanlaurasia]

the red/blue color inconsistency is related to how the sync happens, sometimes it locks to the rising ramp, sometimes the falling ramp. This was (finally) address in the CoCo 3, it always boots one way, and if you hold (F1) I believe, it boots the other. The color oddity there may have something to do with that composite mod.

[@chadhartsees]

Half the fun is just watching you talk with your hands. Never stop!

[@bairfamilyfarm1336]

Check out “Action Retro”, only recently has he shown himself. The joke going around in the comments was that all Action Retro was just a talking hand!

[@JohnJones-oy3md]

18:40 - I bought this exact manual right off the rack at my local Radio Shack. The more in depth service/repair manuals were a little harder to acquire, IIRC.

[@adriansdigitalbasement]

That is so cool. That is a perfect of example of right to repair done right. Companies like Apple should be ashamed of themselves, even if the contemporary Apple back in the 80s.

[@RobertWCrouch]

“While I’m desoldering these, I’ll do a bit of chatting”… I’d expect nothing less.