selgus

For availability, I'm not sure yet how I wish to distribute it. It's a lot of work to make one unit. It does require for me to salvage all the custom chips from a working 7800 console (plus the crystal). All the passives are smd parts, plus the glue logic are done in smd, instead of salvaging them from the donor board. So just need to figure out how I wish to do this, and keep it as a hobby. Price? Gosh, I really have no idea.. though the way I like to do my projects is to just charge what the cost of materials were. Like I said, it is a hobby. I know some folks like to make back the cost of the R&D to make the first unit (and that is totally reasonable imho), but I do this for fun and the love of ATARI and electronics. Sorry, I couldn't give you a more direct answer, but stay tuned.

Okay, I lied.. I did one more revision and waiting on the pcbs right now. I modified the video circuit to have a much better quality for the composite signal fed into the lcd. Instead of the simple transistor amp I'm using a video amp, like in the uav enhancer boards, and an isolated voltage regulator for this sub-system. I needed to rework some of the board and removed the original 7800 circuitry while at it. I did a few other tweaks for better assembly and fit into the enclosure and hopefully I'm not lying this time when I say this is it.

Assembled one up.. still need to deal with the cpld programming. Pay no attention to the 18-pin socket being used for a 16-pin ic. I couldn't find an ultra-low profile machine socket in 16-pin configuration at my normal suppliers, so I just popped out the two top pins and magic.. 16-pin version.

I did not know this.. thanks for this info!

I'm not a fan of this choice. Using some SMD parts allows for smaller designs, better dealing with heat, using modern parts, etc, etc, etc. If you can solder TH, you can learn, very easily SMD soldering (imho). I belong to the R2 Builders Club and at a previous DroidCON, I did a session teaching SMD soldering with a small project. In a short amount of time, I had a con fun of builders, all different skill levels, being able to successfully build pcbs. It seems to be more of a mental block than lack of skill. Practice goes a long way, too.

...And assembly is now completed.. Outside of installing the ATARI chips and flashing my own bios..

As I was assembling the portable, I was trying to organize all the parts from multiple portables I have been building (the xe, sega genesis and this 7800). All these parts have been sitting in their Mouser boxes and bags and every time I build one of these things, I need to sift through the boxes to find the correct parts. I use those Harbor Freight storage cases in my shop, so I sorted all of these projects into these.. While doing so, I was sorting some capacitor networks/arrays and when labelling I saw an odd value.. 100pF. Part of building these portables is you become very aware of every component and where they live in the pcb. I was confused because I didn't remember where this part would be placed. That's when I realized my capacitor math mojo was off, and I had ordered a part an order of mag off. 1nF != 100pF, but 1000pF. So I had already installed the cap arrays onto the pcb, therefore I needed to remove those components and install the new ones (which just arrived today). Good thing I hadn't started installing the ic sockets, as they go over lots of the surface mounted parts, including these caps. Though the boards is far along in assembling, just some of the large parts are left..

Got my boards today, will build one up after I finish assembling the 7800 Portable pcb first (since it is currently on the workbench electronics table)..

Some more progress.. all the passives now completed, surface mounted ics, usb, and misc other components.. still need to do the transistors, some inductors, leds, connectors and all the custom chip sockets.

I feel like a human pick-n-place machine, though with just some tweezers, magnifiers, my soldering and hot air stations. There are hundreds of parts, so this can be tedious.. as I do it in just my spare time. Most of the passives are assembled, many of the diodes and then on to the power ics and such..

Got some pcbs back now, though I did a couple of modifications before submitting this board design (I added proper connectors for the controllers and video, instead of the pin headers) and now I can start assembling..

I found a pre-made cable with built-in pogo pins, plus registration pins, so I did make a slight change to my pcb. I made a footprint for said cable connector and reworked that area to make it fit. I'm going to make some test boards for this one instead of the previous design.

Okay, really my last revision of this pcb! 😀 I made the via pads on my jtag connector too big for the pogo pins I wish to use for programming (I don't want to have an actual jtag connector on the board, that would be used just once). So while adjusting that, I decided since I already modified the board to support 8K banks, instead of 16K ones.. I have extra i/o pins, let me add support for 4K banks. This allowed me to clean up some traces too, so win-win.

I took one more revision of this pcb, this time changing the cpld to the atf1504as, which has around 3x i/o pins. This now allows me to remove a few ics, the inverter and flip-flop now being implemented in the logic. I also now have all the data lines as input and can handle 8K rom banks, instead of 16K ones.

Worked on this pcb a bit more. I want to thank @Eagle and @rj1307 for sharing information and support from their implementation of the SN76489 on their flash cartridge. I needed to add support for locking the data lines while writing to the SN. I tried to get this logic into the cpld, but I didn't have enough i/o pins to create the flip-flop, so I added a flip-flop to the pcb, driven by the cpld. I needed to move things around and re-layout parts of the pcb, but that is completed now.