Tandy / TRS-80 Coco 3 Quick Review and Teardown

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7 жыл бұрын

I managed to pick up a working Radio Shack Color Computer that has never been opened up. In this video I give a bit of a rundown on the machine and then open it up to take a look inside.
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Пікірлер: 44

@danadams1030 4 жыл бұрын

I learned to program on a CoCo 2. I loved that little machine.

@JamesJones-zt2yx 4 жыл бұрын

The serial port is just one example of the way Tandy burdened the 6809 everywhere possible to make the computer as cheap as possible. It's a tribute to the excellence of the 6809 that it performed as well as it did despite such abuse. One notorious example: the mouse and joysticks, as you mentioned, use a resistor to feed the six-bit A/D converter, so that as is they could only give x and y coordinates from 0 to 63. The "high-res joystick adapter" used a capacitor so that in combination, one could get high enough resolution to specify coordinates on the CoCo 3's higher-resolution screens. You learned *very* quickly to keep your joystick or mouse at the top left-hand corner of the screen whenever possible because the higher the coordinate value, the more CPU cycles it took to read the bargain basement hardware. If you want to see decent 6809 computers, check out: the Commodore SuperPET, which had a 6809 in addition to the 6502 on other (pre-Amiga) Commodore computers the Fujitsu FM-77AV, which had two 6809 processors the SS-50C bus computers like Gimix or Smoke Signal Broadcasting. Gimix offered I/O hardware that was the opposite of the CoCo, supporting interrupts and DMA.

@derek8564 6 жыл бұрын

I used to have one of these...thanks for the walk down memory lane

@MickeyMousePark 6 жыл бұрын

Piece of trivia for you about the warranty stickers...if the sticker is black with white lettering it is from the factory..if it is white sticker with black lettering it is from a TRS service center..sometimes on the white stickers we would write a 4 digit number which was the service center that last repaired it.. I was a manager at a TRS computer service center in the 1980's

@RetroLogicLaboratory 6 жыл бұрын

Hey I didn't know that! Thanks for sharing. I decided to check my Model 4 but unfortunately no warranty stickers left on it. There is an "Upgraded to 26-1069" black text on white sticker over the nameplate. I also used to work at RS, but on the retail side.... and I missed the TRS-80 era of course by the time I was old enough to work there.

@MickeyMousePark 6 жыл бұрын

WOW a dual disk drive 64K Model 4 ..somebody splashed out $1000 to upgrade it..very posh hehehe

@Lilithe 5 жыл бұрын

Good condition CoCo3: - Bangs it around - Doesn't steam off the flawless warranty label, just stabs it Is this what the opposite of ASMR is?

@TC-uy8ng 6 жыл бұрын

I still have one of these in my closet, with both a floppy disk drive and the cassette in perfect condition. I just need a monitor. Spent many hours on this back in the day.

@RetroLogicLaboratory 6 жыл бұрын

Awesome. You might find if you get it running you'll have a lot of fun with it. If it's a Coco3 a friend of mine picked up a device called a "switch-a-roo" recently which is a pretty inexpensive way to hook a Coco 3 to a modern monitor. I don't have one myself, but he seems to be happy with it.

@TC-uy8ng 6 жыл бұрын

Thanks for that info. I could probably use the composite video/audio outputs to my tv's external composite inputs. Fortunately my tv has them for vintage connections. The coco's rgb output would be nice but I doubt today's flat screen monitors would support that format. It would be fun to play with it again. I did a lot of 6809 assembly language programming back then. My Coco3 is in perfect shape, if I recall.

@johnsmith-xw4ez 4 жыл бұрын

I have a Tandy CM-8.

@gregferguson7737 4 жыл бұрын

Floppy drive is especially rare. Hang onto it :)

@WalterGreenIII Жыл бұрын

Tandy CM-8 and Magnavox 8CM515 were basically variants of the same monitor, the difference being the 8CM515 can input RGBHV and TTL-RGB as well as composite and Chroma/Luminance inputs. The 8CM515 does not have the appropriate plug for the Color Computer 3, but a simple cable with the CoCo3 10pin plug on one end and the DB-9 for the monitor on the other works fine *if wired correctly). The cable is available on Ebay. The 8CM515 has a distinct advantage, since it accepts composite and RGB, you can do artifact colors by switching to composite. On the RGB only CM-8 you see Artifact colors as black and white. Or you could hook up both your coco2 (with composite mod) and CoCo3 via RGB to the 8CM515 at the same time. Switching from RGB to Composite would allow you to switch between computers without needing to plug and unplug your monitor.

@PotholesInMyLawn 4 жыл бұрын

I started with a CoCo2 then CoCo3 Then Amiga 500... still have my Amiga.. love that machine.. but my CoCo3 was my Hero!!

@alhartman66 6 жыл бұрын

The Coco had licensed games like FS1 Flight Simulator, Zaxxon, and Arkanoid among others. And many of us who were serious about accessing BBS systems had the RS-232 Paks. They were not rare at all.

@jimb032 4 жыл бұрын

Don't forget Kings Quest by Sierra

@8bitsinthebasement 3 жыл бұрын

Great video man. I don't think that I'll ever be able to have a working CoCo 3 myself though. Very few PAL ones were made and the US ones are incompatable electrically even with a voltage converter. The 50HZ rate of European current will cause the CoCo's PSU to drastically overheat even if converted from 220V to 110V. Or, at least thats what I've heard. ;)

@doctorx0079 6 жыл бұрын

Cool intro

@peberdah 5 жыл бұрын

Can this Coco system been implemeted as a daughter board that plug on a Raspberry board, to make modern version where only specific functionality is to be developed. thanks

@MrAntimomontesano 5 жыл бұрын

Hey I got a Coco 3 tonight; it's my first Tandy computer ; I've been a Commodore guy up until now ; does a regular RCA component cable work in a Coco 3 to Commodore 1702 or 1701? The colours at the back are red for video and white for audio, but I see people on KZfaq plugging white into red and red into white; I'm used to video being yellow? Or which cables can I get for RGB? I have monitors 1701, 1702, 1902A, & 1802-CM-141 all by Commodore & I also have Sony monitors PVM-2530 & PVM-5041Q

@RetroLogicLaboratory 5 жыл бұрын

Hey that's great - welcome to the world of the Coco! Getting a monitor hooked up might be a little work but there's a bunch of options. The Coco 3 video out is "NTSC Composite" which still is on a lot of TV sets - at least in North America. The video won't look great though as the colors get blended together. I think the 1702 and 1701 monitors might not work and if they did they will be black and white- as the chroma signal seems to be separate... but I don't know enough about Commodore hardware to say for sure. On 1802, there appears to be a Video input, that should work as well, but like the TV composite inputs, the colors will blend together You will need to set the COMP/SET/MONO switch on the front of the monitor to get the best results (either COMP or MONO). One popular option is to use a community built project called the "Switch-a-roo"which converts Coco RGB to SCART, which you can then connect to the Sony PVM monitors with this: www.retrogamingcables.co.uk/sony-av-accessories/sony-pvm/sony-pvm-scart-converter The Switch-a-roo is here: cocomanbiz.wordpress.com/ You will need *both* the Switch-a-roo and the SCART to Sony PVM adapters to make this work. If you are really adventurous you could build your own cables for the RGB output that is at the bottom of the coco- it uses a "standard" (for 1985) 15kHz RGB output. But that's going to be quite a bit of work. I think the Amiga monitors *might* support this interface but I'm not sure.

@twistedyogert 3 жыл бұрын

I have a question, I just got a Co Co 1 from a friend. I've used it before so I know it works but should I "pop the hood" and see if any parts are close to failing?

@RetroLogicLaboratory 3 жыл бұрын

Typically in electronics this old, capacitors can go bad, but the Coco's in general seem to have used pretty good components and I've never seen any with leaking or badly failing capacitors. I'd just go ahead and try it out. Mind you, taking it apart to look inside is always fun so you might want to do that anyway.

@WalterGreenIII Жыл бұрын

In the CoCo3 the RS-232C was improved, it can communicate at 19,200 baud. CoCo2 could not.

@StarsManny 3 жыл бұрын

If I bought one of these, would I be able to run it on a modern flat screen monitor? I realise I'd need some sort of adapter if that was indeed possible.

@RetroLogicLaboratory 3 жыл бұрын

Hi, sorry for the slow reply. Yes you can run these on a modern flat screen. There is something called a "Switch-a-roo" that is a Coco to SCART adapter. Then you need to buy a SCART to HDMI adapter and you are set. Works really well.

@panographic 4 жыл бұрын

but you didn't talk about the 6809 processor (which was one of the first CPUs with a multiply instruction)

@ms-ex8em 4 жыл бұрын

Hello I typed in write on from dragon user magazine 1985 it won’t work but can you help me out? Thanks.

@tenminutetokyo2643 Жыл бұрын

Them power regulators on TRS-80s sure are weird.

@gregoryroscow5846 5 ай бұрын

Not all CoCo 3s were made in Korea. I've got one made in the USA.

@AndrewKarpyszyn 5 жыл бұрын

Has anyone ever come out with a "CoCo 4" ? Something up-to-date for 1990; 2 or 4 6309s running at 4Mhz, 2 or 4 megs of RAM, running NitrOS-9, that would be a great machine to play with....

@drewlsy 5 жыл бұрын

I own a Coco 2 TRS-80 but doesn't work, and I don't know where to start as far as what to look at to determine why. What would you say would be a good place to start to trouble-shoot it. Is there anything notorious about faulty parts or what not with respect to the circuit board. TY.

@RetroLogicLaboratory 5 жыл бұрын

Hi, thanks for watching my video. Did you check out the Coco 2 teardown kzfaq.info/get/bejne/iZadl6mXsr6vqIE.html I posted yesterday? That will at least give you a description of each of the chips. The "reset button" test is a good starting point. When you plug it in, and press the reset switch at at the back of the machine can you hear the relay click? If not, check is the power supply fuse as a starting point. Next thing to try is to re-seat all the chips- sometimes they come a little loose. These are really reliable machines and are pretty easy to fix as none of the critical parts are custom. Probably the biggest chance of failure would be due to someone plugging in something bad into the cartridge slot (like sticking a butter knife in there). That will often kill the CPU - but they are cheap to buy online. Let me know if any of this helps or if you have any more questions. Good luck!

@drewlsy 5 жыл бұрын

@@RetroLogicLaboratory THANK YOU. I've had some life changes in the new year, sorry for not replying when you replied initially. I have yet to implement your list of things-to troubleshoot, but when I do you will be the first to know the results. Again, thanks. Oh, and to let you know, there is no power that seems to go into the unit. The TRS is non responsive; no screen or anything.

@drewlsy 5 жыл бұрын

@@ericklirios4141 Thanks for the referral, Will do! Sounds like a group specific to the model and brand that i own. I have a couple cool games that it came with (a dungeon one) that I am looking forward to playing once I get it up and running. Thanks!

@310McQueen 5 жыл бұрын

Pretty sure theere's no warranty anymore after thirty years anyway.

@ms-ex8em 4 жыл бұрын

Write on is a program for the dragon 32 and 64 thanks. I can send you the file via email?

@andrewdupuis1151 5 жыл бұрын

I still have Tandy Color Computer 2 why do they call it TRS-80 Coco ?

@gregferguson7737 4 жыл бұрын

Tandy Radio Shack COlor COmputer (see the capital letters). The 80 came from the Z80 in the original TRS-80 (this used a 6809E but Radio Shack wanted to build on their legacy of the TRS-80)

@emrek99205 4 жыл бұрын

@@gregferguson7737 I thought the 80 had to do with the year their first processor came out. 1980.

@gregferguson7737 4 жыл бұрын

@@emrek99205 smart but incorrect. The TRS-80 (later renamed TRS-80 Model I) came out in 1977. Tandy wanted to encourage adoption and use brand recognitio of the completely different and incompatible CoCo using Motorola 6809. I am getting old - I lived through all that stuff LOL In those days I used to pore over the Radio Shack ads that came.in the newspaper and dream of having one so I remember a bunch of dumb trivia about them

@8bitsinthebasement 3 жыл бұрын

You know they toyed with the idea of calling it the TRS-90. Due to the use of a 6809 instead of the Z-80.😀