1. Not old. Vintage. :)

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

Discussion in 'SIG: 8-Bit Hardware' started by M.D.Baker, Sep 18, 2021.

  1. by M.D.Baker

    M.D.Baker Chief Officer

    Blog Posts:
    Just read your post @Vyper68 , but I'm off to work so I'll reply more later...
    Vyper68 likes this.
  2. by Vyper68

    Vyper68 Chief Officer

    Blog Posts:
    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 ;-) )
    Andy Barr and nysavant like this.
  3. by M.D.Baker

    M.D.Baker Chief Officer

    Blog Posts:
    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)

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