Researching the TRS-80 Coco 1/2/3 repairs & upgrades and differences between them.

Just read your post @Vyper68 , but I'm off to work so I'll reply more later...

 

Well I’ve been beavering away on my PAL CoCo the last couple of weeks and it’s been interesting. I removed the RF Modulator and fitted a Composite mod, the output wasn’t great in Alphanumeric and very poor in High-Res. So I found a video on YouTube from Australia ( for some reason Tandy CoCo’s were popular down under ) The video showed how to do a S-Video mod with just 4 components ( 2 Video and 2 Audio ) The output was vastly improved in both types of display.
There seems to be a large amount of games that use the artefacts to create the additional colours in High-Res displays. The PAL CoCo cannot render these correctly so we have a weird display of vertical gaps where the artefact colour would be. I did find some games from a chap in Australia who wrote a game with artefacts for a PAL machine so they are capable of it, it’s just the games haven’t been ported to PAL displays just sold as is. The CoCoSDC works a lot better with a CoCo as well. You can use all the features whereas with the old Dragon you’re constrained to some of the more basic features.
The six cartridges that came with it all work now the edge connectors are cleaned and the two Tandy Joysticks work fine two. I even had a tinker with OS9 Level 1 for a bit.
I have started to build a Symphony 12 clone which gives you 4 AY-3-8910 PSG chips for a total of 12 voices. I have 4 spare PCB’s if anyone wants one ( Matt I’m looking at you ;-) )
L8rs

 

So like an Atari 8-bit NTSC vs. PAL with it's numerous (if not as high per-capita as Coco) high-res games.

I'll think about it, but right now I have two MPI ports with the OojiFlip and the SuperSprite FM+ has sound generator chips on board which can also give a lot of voices/channels if used together and there are already plenty of apps and music players for different formats.

• Yamaha YM2149 Programmable Sound Generator (licensed variant of General Instruments’ AY-3-8910).
• Yamaha YM2413 FM Sound Generation

Not to mention my already having a Pokeymax Quad + COVOX and a Pokeymax 3 on my Atari 8-bits, with all the features below.

• Quad Pokey
• Dual SID
• Dual PSG
• Four channel Covox, with Paula style DMA
• GTIA audio digital pass though

As well as the Dragonfly device for my Atari 7800 which has Dual Pokey's and Covox and Yamaha YM2151 onboard, so really, between those three systems and my Coco 2 & SSFM+ I have all I want and definitely more than need in sound generation possibilities and access to libraries of music for all these different formats.

I doubt I'll want more in the sound department from my Coco 2. For a long while anyway, maybe someday, but the fact is I've been working on hardware for the better part of 2 years, maybe longer, and am on the cusp of finishing some of the backlog and additions I've picked up in the meantime, that in all that time I haven't even explored all the new upgrades and software I've gotten in that time on any of my vintage machines. I've overloaded as it is atm with stuff to explore, and probably next winter before I'll have time to give it all the time and attention it deserves!

I appreciate the offer of the board, but I have to draw the line somewhere of stuff I drop onto this mountain of unused goodies before I bury myself alive and never get to try any of it out. The last item I'm getting for any of my systems for a long while will be the MOOH board for my Coco 2 to fill my one additional MPI/SPI port, which does include the following features, so I will have room for "slave" devices like floppy drives, etc., in the future too, that will use the same MOOH board as the controller. A big reason I chose it over the CocoSDC . Extra memory was another, but I got that with the SSFM+ board. But also compatibility for both MPI and SPI standard peripherals! (just a matter of a jumper or no jumper on two pins and can hot-swap it too!) The OojiFlip also supports both SPI/MPI of course, but only one or the other, SPI with resistors and MPI without, so I leave it as MPI compatible and then can switch to SPI if need be through the MOOH.

• 512 KB RAM, handled by a DAT (dynamic address translator) mostly software compatible with the DAT in the Tandy CoCo 3
• SPI/MPI interface with 4 slaves, one connected to the micro-SD card slot
• ROM socket for 27C512 type EPROMs (64KB)

 

Been a while since I added anything to the CoCo thread but I thought this would be worth adding. The CoCo's while pretty robust it seems the Achilles heel was the keyboard membrane. Similarly to the Atari membranes they were never really designed to work for 40 years and depending on use in the intervening years are failing.
My CoCo2 was one such machine, when I bought it a couple keys didn't work. I stripped the keyboard and tried to examine and clean it. This actually made things worse! so I bought conductive paint and tried that, that didn't help. So I ended up using the CoCo technical repair manual for the keyboard matrix to determine which tracks were failing. So I ended up using stripped Kynar wire held in place with very thin strips of copper tape. This enable me to get a working keyboard. It's not pretty but getting a new replacement mylar is impossible.
This is where a guy called Mike Rojas in the States comes in. He has designed a PCB with low profile SMD tactile switches, 3D printer spacer and a flexible PCB connector and new screws. He has produced kits for the CoCo1, 2 and CoCo3. He is on the Tandy CoCo Facebook group if you are looking for him. Needless to say my kit left the USA yesterday for only $25 plus shipping it was a no-brainer to try and keep this bodged membrane as a reserve for any other CoCo I find. This is one area that the Dragon improves on the Tandy machines as they have Stackpole keyboards like the Oric Atmos.
Anyway it's worth sharing with the group.

 

That sounds like a great deal! My keyboard works perfectly fine, no Mylar problems, but it seemed to be a barely-used mint computer once I cleaned it up, so maybe the mylar is still good because it hasn't been used much. Although, my Coco 2 was one of the early models with only 16K, standard Basic and the "melted" keyboard, so you may be referring to the newer, better keyboard. I've thought about upgrading mine, but since it does work, and heck, it actually feels like an Atari XE style keyboard that I managed to use for about 15 years before upgrading to XL and 800 quality ones.

And I don't plan on extensive keyboard use with this machine, intended mostly for gaming, music and graphic arts (with my new SuperSprite FM+ graphic/sound card) since I use my Atari's with their great keyboards for utilities like Word processing, and of course I have 80 column word processors for it and as you know, the Coco only has 32 column text without it's own hardware upgrades, whereas the Atari can generate 80 column software as well as hardware options, but with my video upgrades I find the software 80 column very legible and I've no need for hardware 80 IMHO. I can also choose to program in 65 or 80 columns through SDX's software text modes too.

The bottom line anyway is I think my current Coco 2 keyboard will do the job fine for me and even though it's feel isn't as good as the later keyboard, I do think it's lower profile keys suit the Coco 2 better for aesthetics.

 

Yeah my CoCo2 is the last 64K PAL model made with the parallelogram badge, T1 VDG and the later model keyboard. It will be interesting to see if the tactile keys work compared to a membrane, when it arrives from the USA.

 

Any news on any US COCO arrivals as yet, Rich? Keep us updated, bud, as this is another machine I know nothing whatsoever about so always good to see what the other machines were capable of.

 

If you are familiar with Dragon computers at all, then you know as much about Coco's too. Graphically on a par with a BBC or Oric I think, sound is minimal without external sound carts. The CPU being a 6809 is a bit harder to compare, but it was a contemporary of the Z80 and 6502 and fits snuggly around them somewhere. But there are tons of new and old upgrades for it. I've got mine upgraded to be on a par with an Atari with VBXE and Pokeymax 3 and extended memory...and about as much software available to make use of the upgrades as the Atari has...