Most liked posts in thread: Researching the TRS-80 Coco 1/2/3 repairs & upgrades and differences between them.

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

 

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.

 

I just discovered that there was a third design change version of the model 1, that did come stock with 64K, but was in a beige case with the "melted" keyboard just like the first version of the model 2. It just has the older OS and Basic roms.

 

I have a feeling this "powers up only" computer only needed it's socketed chips reseated and I felt several push in when I checked them all. I may have a perfectly new, perfectly working Coco 2 here that needs a simple case cleaning! I'll power it up later, but right now I have to go with my brother to get him a car.

By the way, as you can see, the Coco 2 had a very small board and half the case is empty below the keyboard. I do believe this mobo is even smaller than the 600XL's, I'll compare later...

 

Well, since I can't get connected via RF atm, I decided to start research on my specific model number. Mine is the very first U.S. and European Coco 2 model, the version I saw that was beige, but also in the larger Coco 1 style case were sold in Australia and Korea only. Apparently. It is 16K only and does need the second 8K OS chip for full Extended Basic OS, which is required if you want to use a disk drive with the system and be fully compatible with all old and new software.
So I need to buy the OS chip and install it, and they did say that even though the this model uses unusual 16K chips instead of the usual 4116's, the 64K upgrade still uses standard 4164's.

Luckily I have a ton of 4164's on hand pulled from my on hand from all my rambo memory upgrades! So I plug my 4164's in and solder across one spot marked W1 on the motherboard. I did notice it when looking for a 64K jumper that was labeled as such, but that's on Coco 1's only apparently. So I'll have a 64K Coco 2 in about five minutes here, and I can either order a OS chip for it, or wait until I get one of my Atari's running and I can burn the OS to one of my 8K eproms on my Atari eprom burner! Maybe a reason to motivate me to get at least my 800 fixed, since it can use the burner now in XL/XE mode.

I may have to go ahead with the video mod too, and might as well while I have it open, before I'll even be able to test it. So my first test will be after installing 9 IC's and a bit of soldering and after building a small video board.

 

By the way, from what I'ved learned, thought the Coco mouse is analog just like the joysticks, for some damned reason to use it you have to get this 'Color Max' module that plugs into the cart/expansion port and it has another analog port, exactly the same as the joystick ports on the back. And there is a built in GOS environment graphic art program in the module to use with the mouse. From what I've read, it is about the only software that uses a mouse (until the Coco 3), so I'm going ahead with plans to convert it for use with my Atari's. Better graphics and art progams are on the Atari anyway. I didn't get the Coco for that. It only has a 9 color palette and can use 4-9 colors depending on graphic mode.

 

It's all looking Coco sweet there, Matt.

Liking the Douglas Adam area with the Hitchhikers Guide to the Galaxy Infocom adventure bits too.

So much to interest the retro computer enthusiast and mine's filling fast too.

Just a shame we're so distant else a visit to view, chat & discuss would be a must!

Never mind, sending pics and talking on here is the next best thing.

Keep on enjoying your passion, fellas.

As ever, great to see the collection continue and the joy spread.

 

I decided to go ahead and move the 800 and move in the Coco 2. At the moment the 800 is disassembled inside the case anyway and if I finish the job, I'll just set it up temporarily where my 1200XL is and just use it's peripherals until the 800 is moved to the office trailer or the 1200XL is fixed.

So here is a proper Coco 2 setup, including a tape recorder with cable to the Coco, Coco mouse and Coco joystick, connected to a 14" CRT TV I dug out of storage (salvage from a customer junk-haul off job-I wasn't using it for my Atari's as they are PAL not NTSC) that is grey metallic color and will match the Coco 1 and peripherals when I get it. Unfortunately I don't have a remote for this CRT TV and it seems to be stuck in AV mode and I can't get it to change to RF channels, the channel buttons do noting unless I press the menu button and nothing in there to change channel off of AV mode! So I'm still going to have to do composite video mods to my Coco's before I can use this TV, unless I find a remote or some other way via the TV buttons!

All those cables I got with the Coco joysticks and mouse that I guessed were for MIDI, are actually 5 TRS-80 Coco tape drive cables! And one cable that had an Atari style 9-pin joystick plug on it and audio style mini jacks at the other end, like the Coco tape cable, is also a tape drive cable, I found out, but for a Texas Instruments TI-99/4A and another grey cable that looks like it has Coco style plugs on it, is in fact a monitor cable for a TI-99/4A!

 

Did I mention that the "melted" keyboard of my Coco 2 feels nearly identical to the touch and travel distance of the Atari XE computers "mushy" keyboards? Keyboard nostalgia without the XE!

But at least it will still be an upgrade to the chiclet keyboard of the Coco 1 when I get it, and I do think the look fits the Coco 1 better than using a Coco 2 for 3 full-travel keyboards on it.

Also, by the way, the cheap, wireless $10 PC keyboard I am using right now, with full-size chiclet keys, feels like the XE and Coco 2 melted keyboards in the "mushy" feel and travel distance too. I'm used to both mushy and fantastic feeling keyboards between my Coco/PC and 1200/800.

Of course I have better PC keyboards I could use, but they have cables and are less convenient atm.

 

The brand is Durabrand. I found out it's made in China, the rear sticker is all there with manufacture date of June 2005 (I thought they stopped selling CRT's before 2K5!?) and model number BH13040D.

I found and purchased a remote for it on eBay, with free shipping for less than $10. Actually, I need to go see about buying one for that 23" CRT I have now too, though I can change video modes without a remote with it. But if I can fine one for it for less than $10 I'll buy it too.

 

Excellent, Matt. Well sourced, mate.

I would have thought CRTs would have stopped being produced sometime late 90s/very early 2000s but there you go!

 

I found the remote for my other 23-25" Sanyo CRT too, for even less than the Durabrand.

While I was on eBay, I also bought a couple of Avalon Hill games, NIB, one for less than $20 and the other for $25. One is VC, a Vietnam strategy war game, and the other, Conflict 2500, a strategy game on a galactic war scale. As some may remember, I've been on a quest to collect strategy war games, and also any games from the companies that used the heavy cardboard boxes with similar construction to board games. As Avalon Hill and SSI and Epyx and Origin did.

I had remembered when looking through specifically Avalon Hill games for sale in the past, that many of them, especially the cassette tape versions, had versions of the program for several micros on the tape. I double-checked my Legionnaire and Telengard A.H. games, but they are Atari specific. But I made sure the games I bought this time, in light of my new TRS-80 Color Computer, that I bought A.H. games that included versions for both the Atari and TRS-80 Coco's. VC and Conflict 2500 do. That way I'll have a couple commercial games for the Coco to play soon, though I am learning to record Coco tape game .wav files back on to cassette in the mean time.

I've also ordered an upgrade board for the Coco 2 to allow 28-pin eprom to work through the Coco's 24-pin Extended Basic rom socket (24-pin versions of the rom are ultra rare)so I can burn that on a 2764 eprom using my Atari and the XL/XE eprom burner.

I also found out that there is a newer revision of the 6809E processor in the Coco that works better and has added abilities but still 100% pin-compatible.

Also a new MMU board that goes in the 6809's socket and the the 6809 plugs into it, and this new memory unit, along with upgraded ram (separate upgrade), allows Coco 1 & 2 to run the Coco 3's OS/9 multi-tasking OS! The only caveat is the Coco 1 or 2 with these upgrades will still not be able to run any Coco 3 OS/9 software that uses the Coco 3's new graphic modes they don't have. But lot's of Coco 3 software will run, except mostly games which is what uses the new graphics mostly.

Another new discovery is that with the last revision of the Coco 2, they put in a new VDC chip, the chip that handles Coco's graphic and text modes and this new chip has the lower case text abilities that the original didn't have. I can upgrade to it too.

And more...though not as much new hardware as we have for Atari 8-bits. There is an SD card drive, and something like SIO2PC/APE and adding additional new sound chips, like Pokeymax does, with YM and Covox and DAC, but on the Coco they are boards that plug into the cart/expansion port (basically the Coco's PBI/ECI port) instead of internally. And more...

 

What can I add, fella?

I'm a big big box wargame and strategy collector too as I just adore all that graphic art, bumpf and paperwork you get inside which helps to set the scene in the player's imagination.

The fact you're getting Atari and TRS versions on the same tape is indeed a double bonus, Matt.

Some great explorations you're enjoying with this new set-up, mate.

The sky's literally the only limit with some of this retro kit.

 

I haven't even loaded a program to my Coco 2 yet, though I have a cassette player for it and have recorded a couple of .wav files. In the spurts of free time that I've had over the past couple of months, I've only been doing upgrades to my Coco 2, and my 7800, and my 800, sort of rotating between them. Currently I'm in the middle of an S-video and audio out mod on my Coco 2 and one for my 7800 as well.

The Coco 2 mod I am going by somebody else's schematics and on the 7800 it's a combination of a couple different mods schematics by others and some of my own design where I felt I could improve over other's. And of course the 800, while mostly done mod and upgrade-wise, is undergoing the face-lift and make-over. A the moment I actually don't have any of my 8-bit systems up and running, all are in need of repair and/or in the middle of upgrades. Of course winter is approaching fast and I should have much more free time to see these projects and several other finished finally.

Though I mentioned them above in posts, here is what I've done to my TRS-80 Coco 2 thus far in list form:

-upgraded internal ram from 16 to 64K.
-upgraded OS with adapter board for larger pin eprom and added MS extended Basic
-upgraded Motorola HMOS 6809 MPU to newer, compatible Hitachi CMOS 63x09E MPU used in Coco 3's with the 1.78Mhz turbo mode and extended features.
-replaced all 74LS series IC's with newer 74HC or 74F series
-removed old RF box/board and am upgrading video with replacement video board
-upgraded the MC6847 VDG to the newer MC6847TI with lower case characters and true descenders.

I want to get the MOOH board as it has all the other upgrades I want to do included on it, but I may have to settle for the SDC board and do the 512K ram and OS-9 upgrades myself. I want to buy an original multi-pack device to plug in several modules at once, but I may have to build my own board and case for that as well as originals are expensive and rare and only a 2-port multi-pak is still available from home-brew dealers and I want at least a 4-port if not 6-port.

Once the video board upgrade is finished I will start investigating the TRS-80 tape and cartridge software library as well as the Dragon's and look more into what needs to be done for Dragon/Coco cross-compatibility.

Here is a link to hardware upgrades that are compatible with both Coco's and Dragon's.

https://thezippsterzone.com/hardware/

 

Yes, I'm aware of the VGA board. I decided against it myself because I think I will be perfectly satisfied with the quality of video outs I make along with the external video-to-VGA adapter/upscaler that I already have and use for all my video/S-video equipment, and in fact, I suspect works better as it does with other similar devices I've tried and would rather use an external font/character board where the VGA board rests.

External font/character board:




And that VGA board is ultimately no different than my external VGA adapter (except maybe works with color artifacting) but my external adapter has more advanced features for a better picture:
http://www.ambery.com/dvh4.html

 

It would give me 32KB of extra RAM accessible via Machine Code. The Dragon 64 has a slightly different ROM and an extra interface. So not a proper D64 but it would run OS9

 

I sent out another email to Tormod today, or yesterday. Anyway I did get a response this time, and he did say he had responded to my previous emails so it was an error on my end as to how I missed them.

He said he was working on a new batch of MOOH boards, interrupted by the holidays, but will be shipping them in January. So I've placed my order and am just awaiting a response as to if I can pay now, or need to wait until they are done. I want to pay now in case I forget to set aside money for it in January and end up being flat broke just for some reason just when he asks me to pay later.

I'm very happy though, as this board takes the place of the SDC board, plus extra ram and an SPI (replaces MPI controller) expansion header for other drives built in, which I think means I won't need a drive MPI controller pak for a disk drive or two. Though I need to find out exact differences between SPI and MPI, I may still need a DI special cable or adapter to connect MPI style disk drives to SPI. Plus 512K extended ram that I'd have had to buy another board on top of the SDC to have. The MOOH also has rom socket on-board for burning 64K eprom and using NitrOS-9 which is an updated version of OS-9 for the Coco model 3, for handling the extra memory. Or another new multi-platform OS called Fuzix based on UNIX. So my Coco 2 will have it's original OS and I can have two other ones that use the extra memory and make programs for the Coco 3 (only the ones that don't use the 3's new graphic modes, so no games)work and Unix based programs.

I'll probably 3D print my own case for it, there's probably a print for one I can download made by someone else, whether unique or a clone of a program pak case anyway.

From the site:



The MOOH is a cartridge board for the Dragon and CoCo 1/2 featuring:

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

The board is designed to allow Dragon and CoCo 1/2 computers to run multitasking operating system such as NitrOS-9 Level-2 and FUZIX, offering virtual address spaces for each process, as well as fast mass storage on SD cards. Other SPI devices can also be connected. The ROM socket acts like a standard cartridge ROM, additionally offering software selection of multiple ROM images. A boot ROM allows the MOOH to be used without the need for any other storage devices or MPI. The "SDBOOT" ROM loads a program or operating system from the SD card on power-on.

• Plugs into the cartridge port - without modification of the computer
• Dimensions 99 x 96 mm (fits inside FD-502 and CoCoSDC enclosures)
• Uses standard micro-SD cards

The board comes with a printed manual with programming details, schematics and internal logic code.


It would have ended up costing me more for the SDC and these other upgrades separately. The MOOH is probably the last upgrade I will need to do to my Coco 2, since I did all the other possible ones that don't require a separate board; newer, better CPU, 64K ram, better OS and Basic, video output upgrade, newer VDC chip with lower case text, and something else I replaced...but forget atm...I can't think of any other purchasable upgrades I'd want, except for a Multi-pak expansion so more things can be plugged in at once. But since the only modern alternative currently is a two-slot model, I think I'll just pay the premium eventually for an original 4 slot Tandy/RadioShack multi-pak with a case that matches my system.

So once I get the MOOH board, it's just software and original era peripherals I'll start collecting, just a disk drive and a couple expansion boards like Orchastra-90 or modern alternative, mainly. I'll have to look through all the first and third party peripherals and expansions to see what was and is available. But probably no more internal upgrades to the computer...well, I may eventually upgrade the keyboard if a reasonably priced one turns up, but since I don't plan on using this computer for a lot of typing, I think the "melted" keyboard I have will be fine. It's at least as good as the XE keyboard I lived with for 20 years...

MOOH page: http://tormod.me/mooh.html

 

Something else new and interesting I discovered for Dragon and Coco computers on eBay today, and then I did a search for more info on them. But basically an upgrade board giving the Dragon and Coco computers the advanced graphic capabilities of MSX 2+ machines! (much more advanced than original MSX computers or anything 8-bit including stock Atari graphics*) I may get one of these too, though it doesn't make them compatible with MSX software...so I'll look into it more...they do show a few screen shots of games apparently made for it already, on the site below.

The SuperSprite FM+ 6x09 (for either Motorola 6809 or the newer, faster 6309 by Toshiba?-which I already upgraded too) for Dragon and Coco 1/2 computers. It can be purchased in kit of built forms.



Even without a multi-pak device I can use this with the MOOH since this board has a pass-thru connector! But I'll wait until I have the MOOH first and look into the possibility of buying this next year.


https://www.dragonplus-electronics.co.uk/product/supersprite-fm-6x09-for-dragon-and-coco-computers/

Compared to Dragon and Coco, MSX and C64 and all other 8-bit stock computers graphics besides the MSX 2+, Atari 8-bit graphics are still more advanced overall, IMHO, but then I don't put nearly the stock others do in the number of sprites an 8-bit machine can display at once, and I know both the MSX and C64 have more than the Atari. But the number of graphic modes (bitmap and character), 16 times larger palette, ability to mix modes and far more colors on screen as a result, and faster non-sprite graphic abilities, like 3D and 2D scaling and smooth horizontal and vertical scrolling of the Atari put it head and shoulders above all other 8-bit computers IMHO.

Keep your sprites if that's what you like, to me it's just one small aspect of graphic capabilities, especially with Atari graphics. Besides, the Atari has enough P/M's (4 8x240 and 4 2x240 or 4 8x240 and 2 4x240 or 4 8x240 and1 2x240 and 1 6x240 or 5 8x240 or combinations to create multi-color sprites) if multi-plexing is used and changing the display list, with nearly double the speed processing of the MSX and C64, it can hold it's own then.

And no matter what the Atari 8-bit always has the advantage of "sprites" 240 pixels tall that allow many interesting things to be accomplished in games or for masking purposes, more colors on-screen, etc. So if one thinks about it the Atari's P/M graphics are more versatile, can be massively larger vertically and nearly "free" multi-plexing abilities with the use of DLI's alone, without a multi-plexing engine, even though there are less P/M's, aren't they still more advanced than C64 and MSX sprites? I believe so, at least in versatility if not amount.

Sorry, being artistically inclined and an eye for graphics, I tend to be a bit zealous about what I think is important in graphics and sprites aren't, except in one of the versatile uses the Atari can use them for; more colors on the screen like with Rastaconverter images and high-res multi-color using P/M's for more colors on screen. And that's also what makes me excited about the possibility of MSX 2+ quality graphics on my Coco 2!

*This is an Atari VBXE or Apple IIGS quality (actually I think this board and the VBXE are much more advanced graphically that the IIGS, but for sake of argument...)upgrade for the Dragon and Coco computers!

 

Just an update on the Coco/Dragon cards I spoke of above (links in the posts)

I did finally get in contact with Tormod and he says he's making more MOOH boards now and they will be ready in January, so he's aware I want one including the SD card and boot rom. So I should have it in a couple of months.

Regarding the SuperSprite FM+ 6x09 board, I just ordered it, along with an adapter board for the 6309 that provides what I need to use with this board and access it's turbo 1.78MHZ mode without need of upgrading to the later revision SAM chip in my machine which I have been unable to find anywhere anyway.

Also, since the MPI multipak expansion units are so expensive (over $150 on average) and the newer versions made by enthusiast like the Mega mini multi-pak or the mini multi-pak sold out and no sign of more being made, I'm resorting to a Gerber file of an older (from the 90's I think) multi-pak build-it-yourself PCB and I'll get one ordered and made for me from PCBway or someplace then build it and print a case for it. However, in the mean time I also purchased a two-spot multi-pak device from the same place as the SuperSprite board, and though it's just a bare board it was only $25 and will at least allow me tho have the SuperSprite FM+ and MOOH plugged in at the same time. And since I probably won't be buying a disk drive or other peripherals soon with the MOOH's SD card, I probably only need the two spots for a while.

But I just spent over $200 with shipping on the SuperSprite board and the extras for a computer I bought for $50...so I'm all in now, and with all the immediate upgrading and modding I've been doing I still haven't run a single program on it yet or played a game. But it will have all the top and latest upgrades opening up a lot more software and OS's for me to use when I do get around to it. And especially all the software that's starting to come out for the SuperSprite FM+ which is similar in many ways to the Atari's VBXE giving it graphic abilities that even far exceed the Amiga and and ST's and I think really more comparable with Atari Falcon graphics with these two boards. Apple IIGS eat your heart out!

 

well here we have my first attempt at 6809 assembler using the DASM/DEMON Cartridge. It should work on a CoCo2 if the Text screen starts at &H400 to &H600.

 

Pretty much 6502 with some funky extra label variations.

Does it have to have the @ to define it as a label?

 

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

 

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.

 

Very interesting research there, Matt.

I know diddly squit about these Coco machines so we learn something new every day - especially on here!

Good luck with all the upgrades and purchases ahead to make this a real rock n roll retro machine which fulfils all your ambitions for it.