Make your own ColecoVision

[fieroluke]

Inspired by Leako’s excellent home brew CV I went ahead and made a DIY of my own. 
some key features I wanted to incorporate were:

 

• only use standard components: makes it possible for everyone to build it
• using SMDs but avoiding super small footprints wherever possible
• no FPGA or GALs: no special programmer required (except for EPROM)
• ColecoVision board dimensions make it a useful as a replacement for dead CV boards in the original case
• joystick port ICs socketed, added protection diodes
• 32K RAM, up to 64K ROM mappable in cart space: “built in game” possible
• BIOS disable bit and RAM mirroring enable bit registers
• optional AY 3-8910
• support 9918/9928 PAL/NTSC
• LM318 Video buffer
• TMSRGB on board, Genesis II Mini DIN connector
• chinch A/V jacks
• USB port for game download/development from PC
• switching power supply (buck converter) with 9-18V single supply voltage on standard barrel connector 
• spare sockets support adding more ICs for tinkering and registers

I’m 95% done, need to add the spare sockets and clean up layout.
 

I’m curious if there are any comments or suggestions!

 

 

[Nateo]

Damn, this is nice! Can't wait to see the first prototype build!

[youki]

it would be wonderful if you could add a speech synthesizer. ? 

 

 

[fieroluke]

3 hours ago, Nateo said:

Damn, this is nice! Can't wait to see the first prototype build!

Wait no more, check this out:

 

 

[fieroluke]

29 minutes ago, youki said:

it would be wonderful if you could add a speech synthesizer. ? 

 

 

You can’t really get those anymore…

the SP0256-AL2 was nice and is somewhat still available, but a DMA channel would be nicer for digital sound. Or an MP3 decoder to play CD quality sound with moderate memory requirements…

 

[Pixelboy]

Since you asked for comments, I'd say this is a good opportunity to voice my own.

 

I've monitored your project from the sidelines, and I generally like it, although the purist in me is a little put off by having to drill holes into the console casing to accommodate the video output and/or USB connectors.

 

Could I interest you in one of two different challenges?  

 

Challenge #1: I'd like to see an NTSC version of your motherboard that is a closer "reproduction" of the original, with no extra features, but with more modern parts: 1K of RAM mirrored (I see that Digikey still sells 1K chips, although I'm not sure if they're technically compatible with this proposed project), no AY-3-8910, no USB port, or anything of the sort. The front expansion port would be fully compatible with the Expansion Module #1 and the Super Game Module (Expansion Module #3 support would be nice, but personally I wouldn't require it). The A/V video output would be done via a unified adaptor cable such as one of these:

https://www.ebay.com/itm/233917082078?hash=item36768b69de:g:puIAAOSw7AxgQppL
https://www.ebay.com/itm/193838792824?hash=item2d21b14078:g:S6IAAOSwqLlf9kWs
https://www.ebay.com/itm/351284418398?hash=item51ca2ed75e:g:bcMAAOSw9hdaAGZd
https://www.ebay.com/itm/293136143758?hash=item444046958e:g:FMgAAOSwztddFm43

 

Power input would be so designed as to be able to power the Expansion Module #1 or SGM via the front expansion port just like the original motherboard, and that may increase the complexity of the power supply. Some homebrew game cartridges seem to require a little bit more power than usual, so that would have to be fully tested as well.

 

Challenge #2: Same as challenge #1 above, but with HDMI output: The power plug would be located in the "RF video hole" on the console casing, and the HDMI female connector would be located in the rectangular "power connector hole". In other words, the power and video cable positions would be swapped. CollectorVision implemented HDMI output on their Phoenix console, so I see no reason to dismiss the possibility here, although I realize that it may make the fully-built board more expensive. I think it would be very much worth it.

 

With either challenges, drilling holes into the enclosure would not be required, and I believe this would make it much more desirable as a drop-in replacement for the aging original motherboard.

 

Do you think either challenges are doable? I'd be willing to discuss the finer details if you are interested.

 

[SiLic0ne t0aD]

HDMI, RGB or even VGA output is pretty much a must nowadays (at least for me anyway), as many of us already have modded ColecoVision's with those output types, plus the Phoenix with HDMI. There's absolutely no way in hell I'd ever go back to composite. ?

 

A Genesis 2 or 8-pin mini DIN jack would be perfect! That's what I use with my Rgb modded consoles, so that's one less cable to buy.

 

Anyways, really promising looking project so far though! Exciting stuff, keep up the great work. ? Been wishing for a drop-in replacement for many years now, so I'm definitely interested in a couple of these PCBs whenever they're ready.

Edited November 17, 2021 by SiLic0ne t0aD

[fieroluke]

4 hours ago, SiLic0ne t0aD said:

HDMI, RGB or even VGA output is pretty much a must nowadays (at least for me anyway), as many of us already have modded ColecoVision's with those output types, plus the Phoenix with HDMI. There's absolutely no way in hell I'd ever go back to composite. ?

 

A Genesis 2 or 8-pin mini DIN jack would be perfect! That's what I use with my Rgb modded consoles, so that's one less cable to buy.

 

Anyways, really promising looking project so far though! Exciting stuff, keep up the great work. ? Been wishing for a drop-in replacement for many years now, so I'm definitely interested in a couple of these PCBs whenever they're ready.

If you look closely, there is a Genesis 2 Mini-DIN jack on board, the TMSRGB is also on board. The Chinch jacks are only for those who prefer those. Composite video can be jumpered to Mini DIN as well instead of pure sync. Audio on Mini DIN is stereo with the AY but can be switched to mono if desired. Soldering the Rev.A board right now with more features. I’ll keep you posted.

[fieroluke]

7 hours ago, Pixelboy said:

I've monitored your project from the sidelines, and I generally like it, although the purist in me is a little put off by having to drill holes into the console casing to accommodate the video output and/or USB connectors.

 

Could I interest you in one of two different challenges?  

 

Challenge #1: I'd like to see an NTSC version of your motherboard that is a closer "reproduction" of the original, with no extra features, but with more modern parts: 1K of RAM mirrored (I see that Digikey still sells 1K chips, although I'm not sure if they're technically compatible with this proposed project), no AY-3-8910, no USB port, or anything of the sort. The front expansion port would be fully compatible with the Expansion Module #1 and the Super Game Module (Expansion Module #3 support would be nice, but personally I wouldn't require it). The A/V video output would be done via a unified adaptor cable such as one of these:

 

Power input would be so designed as to be able to power the Expansion Module #1 or SGM via the front expansion port just like the original motherboard, and that may increase the complexity of the power supply. Some homebrew game cartridges seem to require a little bit more power than usual, so that would have to be fully tested as well.

 

Challenge #2: Same as challenge #1 above, but with HDMI output: The power plug would be located in the "RF video hole" on the console casing, and the HDMI female connector would be located in the rectangular "power connector hole". In other words, the power and video cable positions would be swapped. CollectorVision implemented HDMI output on their Phoenix console, so I see no reason to dismiss the possibility here, although I realize that it may make the fully-built board more expensive. I think it would be very much worth it.

 

With either challenges, drilling holes into the enclosure would not be required, and I believe this would make it much more desirable as a drop-in replacement for the aging original motherboard.

 

Do you think either challenges are doable? I'd be willing to discuss the finer details if you are interested.

 

First of all, I appreciate your comments, thanks!

 

Ok, I don’t like drilling holes either, owning a PAL console I don’t have to. The Chinch jacks are absolutely optional for those who want them. Composite can be routed to the Genesis 2 connector (instead of pure sync).

Stereo audio is also on the Gen2 jack, but can be switched to mono if you don’t like it. Pretty much all the extra stuff is optional, you can build it as a “real” CV, with limited RAM, mirroring and all and yet no USB, AY, pause key, RGB, etc. And the hole in the PAL console nicely fits power, Mini-DIN and USB jacks.

The expansion bus is compatible with the Atari VCS Expansion module, I just have to test it. Basically I don’t have a TV with composite in anymore, so that’s a challenge. I can only check if the power supply can handle it (it should), else I’ll beef it up.

 

SGM compatibility has never been a goal since RAM and ROM banking logic are on board, as well as the AY. 
 

The analog A/V video is on the Mini-DIN jack, again, the Chinch can be left off the board.

The HDMI would be a great addition, I agree, but I have no idea how to pull that off. 
 

This started out as “let’s see if I can do it” kinda project, and now I want to get it to work, and I agree, it’s goal is a drop in replacement for dead CVs. The new board  revision even supports the original power and reset switches if you have them, else it’s modern equivalents with 3D printed adapters to the original plastic parts.

 

Next I want to mod the BIOS to map the upper 32K of ROM in case no cart is detected to allow a built-in game.

 

I am not sure the USB was a great idea, because there is no upper 32K RAM to load to (yet) and there not enough space for another RAM chip. But it would be usable to test stuff on real hardware with the upper ROM with data in place and the lower 32K RAM available for quick downloads via USB. Again, it’s optional, and only takes up half a square inch of board space…

 

 

 

[SiLic0ne t0aD]

51 minutes ago, fieroluke said:

If you look closely, there is a Genesis 2 Mini-DIN jack on board, the TMSRGB is also on board. The Chinch jacks are only for those who prefer those. Composite video can be jumpered to Mini DIN as well instead of pure sync. Audio on Mini DIN is stereo with the AY but can be switched to mono if desired. Soldering the Rev.A board right now with more features. I’ll keep you posted.

Yes, I saw that under your bullet points/list as well. That's great news!

I run stereo/dual mono audio through my Scart cables, so that'll work out perfect.  Sounds like you got it covered. ?

[Pixelboy]

4 hours ago, fieroluke said:

Ok, I don’t like drilling holes either, owning a PAL console I don’t have to. The Chinch jacks are absolutely optional for those who want them. Composite can be routed to the Genesis 2 connector (instead of pure sync).

Stereo audio is also on the Gen2 jack, but can be switched to mono if you don’t like it. Pretty much all the extra stuff is optional, you can build it as a “real” CV, with limited RAM, mirroring and all and yet no USB, AY, pause key, RGB, etc. And the hole in the PAL console nicely fits power, Mini-DIN and USB jacks.

Sure, I understand where you're coming from, but given that the ColecoVision is a mainly North-American system and that the US console enclosure doesn't have the large rectangular hole on the back that facilitates the placement of a mini-DIN connector, I thought you'd maybe be open to an alternate version of your motherboard that caters to the majority of ColecoVision fans (living in the US and Canada) who would like a drop-in replacement motherboard without having to punch holes into the console casing.

 

There are a lot of broken ColecoVisions out there, the majority of which are in North-America, so I definitely see a niche market here which you could cater to, and the point of my "challenges" was to outline the preferred requirements of North-American ColecoVision fans, the majority of whom already own a Super Game Module and would probably like to continue using it.

 

But if the point of your project is simply to demonstrate a technical achievement, that's perfectly fine. I was just putting some ideas on the table to take it a step further.  

 

[fieroluke]

1 hour ago, Pixelboy said:

Sure, I understand where you're coming from, but given that the ColecoVision is a mainly North-American system and that the US console enclosure doesn't have the large rectangular hole on the back that facilitates the placement of a mini-DIN connector, I thought you'd maybe be open to an alternate version of your motherboard that caters to the majority of ColecoVision fans (living in the US and Canada) who would like a drop-in replacement motherboard without having to punch holes into the console casing.

 

There are a lot of broken ColecoVisions out there, the majority of which are in North-America, so I definitely see a niche market here which you could cater to, and the point of my "challenges" was to outline the preferred requirements of North-American ColecoVision fans, the majority of whom already own a Super Game Module and would probably like to continue using it.

 

But if the point of your project is simply to demonstrate a technical achievement, that's perfectly fine. I was just putting some ideas on the table to take it a step further.  

 

I'd certainly be open to move connectors around... I don't have access to a NTSC Colecovision enclosure.

Maybe someone can work with me and provide closeup pictures and measurements...?

[Pixelboy]

31 minutes ago, fieroluke said:

I'd certainly be open to move connectors around... I don't have access to a NTSC Colecovision enclosure.

Maybe someone can work with me and provide closeup pictures and measurements...?

I believe I still have a broken US ColecoVision console here, or even if it's not quite broken, I could still send it to you for study, if you want. Send me a PM and we'll work it out. 

 

[fieroluke]

I thought I’d just share what I did today…  

 

Since the new reset switch is slightly smaller than the original CV switch, the old button’s plunger does not work with the new switch. So I 3D printed a tiny washer and it works great.

 

While I was at it I recreated the entire button to see how that would come out - I like the result (printed in grey because it photographs better):

 

 

[fieroluke]

On 11/16/2021 at 7:59 PM, fieroluke said:

You can’t really get those anymore…

the SP0256-AL2 was nice and is somewhat still available, but a DMA channel would be nicer for digital sound. Or an MP3 decoder to play CD quality sound with moderate memory requirements…

 

Rereading the old thread, I did add expansion connectors along the AY-sound chip, including an audio input, so a piggyback board could be created that carries the SP0256 speech synth if desired.

[fieroluke]

On 11/16/2021 at 7:27 PM, youki said:

it would be wonderful if you could add a speech synthesizer. ? 

 

 

I actually made an add-on board with a speech synth, going to try that in the next weeks…

[fieroluke]

The speech add-on boards also showed up today!

 

Follow the project at DIY-ColecoVision