The 1200XL-1mb SRAM upgrade was just released last week, which was very much a personal project as well as the RAMBO XL-II which is also seeing an official release at this time.

The RAMBO XL-II initially had only been discussed and talked about on AtariAge, and also saw an initial release on that platform back in 2022. At the time I needed a way to increase my 1200XL's RAM up to 256K so as to run some applications with a higher memory requirement. The original ICD RAMBO board looked like a good way to do that, but was no longer available, thus the reason I cloned their 1980's era product.

A few years later I encountered some noise issues in the analog video output on that same 1200XL, which after some investigation appeared to be originating from the DRAM and it's support circuitry. Thinking that swapping the DRAM out for SRAM might be a good way to eliminate the noise issue, the 1200XL-1mb board was born. And after installing one, I'm glad to say the noise is no longer present.

So manufacturing files for both upgrades is now downloadable at the RAM tab in my website's navigation bar.

Enjoy,
Michael

After the integration of a MIDI Player to the former FujiNet only plug-in module, I decided it was finally time to release all the changes I had been working on for the last several months. This included fixed firmware for both PS/2 sub-processors, a corrected pad hole size for the CR2032 Battery Holder on the main NUCplus4 PCB, a new combo FujiNet/MIDIplay PCB, new improved Version 2 firmware for the TK-II controller on the 576NUC+, and a new updated datasheet covering many of the changes. These downloads are all provided at the NUCplus4 webpage on this site.

The image below shows a completed board assembly with the new FujiNet/MIDIplay module, as well as the Cooling Fan and Shroud that got introduced a while back. So what you see is a fully packed system with all the bells and whistles.

1. 1088K RAM
2. A8PicoCart
3. Choice of SDrive or FujiNet (selected one at a time via keyboard control)
4. R-Time 8 Battery backed Real Time Clock and Calendar
5. Dream SAM2695 MIDI Synth for MIDI playback

Items shown in RED are the original "4" aspects incorporated into the NUCplus4 name, and a standard part of the Main daughter board.

And this complements the 576NUC+'s Multi OS and Language Slots, PS/2 Keyboard input, and high quality Composite and S-Video Output with VGATE technology.

And even though there's a lot of stuff that's been added via the NUCplus4 daughter board on top of the 576NUC+ base system motherboard, it all still squeezes into a fairly small case that easily fits in the palm of your hand.

Case Dimensions:    5.38" wide x 5.25" deep x 2.25" tall
                                      (147 mm x 133 mm x 57 mm)
Assembled Weight: 17 ounces
                                      (482 grams)

In its present form, this has become my preferred Atari computer system, and as close as it comes to a daily driver for me.

I think what I like best is not only the small size, but also the incredible versatility of having multiple solid state drive possibilities as well as wireless network access. And at least for me, incorporating the A8PicoCart was the optimal way to have cartridge based software that would run at full speed, without the bulk associated with hauling around a bunch of real physical carts. After all this was first and foremost meant to be an extremely portable system that could be tossed in a bag and taken to a meet-up.

This journey first began back in 2020, and after 5 years has matured into what I consider not only one of the smallest Atari computers out there, but also an extremely powerful one. And aside from the rare and somewhat hard to get Atari VSLI chips, is practically built with off-the-shelf parts and based upon open source designs (thank you Atari community).

I think the journey that began so long ago has finally arrived at its intended destination.

- Michael

I got the final boards about a week and half ago, assembled one, and gave it a test. Everything worked as it should.

So my plan now is to build up a 2nd one and drop that off with someone I consider to be the utmost authority on the 1200XL, and who has gotta have the largest collection in the known world, and perhaps the entire universe - Bob Woolley.

Currently I'm waiting for some SRAM chips to show up from China (both the 512K and 64K chips). I'm hoping that I get a good batch, although if not and they turn out to be fakes I won't be out much in $$$.

The 512K chips are in current production and readily available from the likes of Digi-Key and Mouser, but I'm looking for a deal so I thought what the heck I'd give AliExpress a try to see if I get lucky.

The 64K SRAM is a different story, having been out of production for years. However I've bought these in the past from multiple electronics surplus electronics sellers without even one failure, so I'm hoping for the same on this go around from an eBay seller

The great thing about switching from DRAM to SRAM, was that I got rid of the last remnant of video noise producing hardware on my 1200XL, and the results were fantastic!

New Project

So as the 1200XL-1mb project gets wrapped up, I'm off on another. This time I've decided to integrate a MIDI Player aspect into the NUCplus4's FujiNet module.

Since the NUCplus4's FujiNet module already plugs into the entire SIO bus, it has audio input capabilities via the SIO's Audio Input pin. This was already taken advantage of by FujiNet with the Disk Rotate being called out by the emulated S.A.M. voice in the ESP-32's firmware. And it's a simple matter of mixing in additional audio devices through this same pin (e.g.; MIDI Synthesizer).

Now it just so happens that there is a very inexpensive encased module that incorporates the SAM2695 MIDI Synthesizer chip that goes for cheap, and is manufactured for M5STACK in China.

• M5STACK P/N: U178
• Digi-Key P/N: 2221-U178-ND
• Mouser P/N: 170-U178

For our purposes the SAM2695 carrier PCB will get extracted from the plastic case it comes in, and with a small modification be incorporated into a brand new NUCplus4 FujiNet/MIDIplay board.

The original miniature 8 ohm speaker will get dispensed with and I'll be routing the Class D amplifier's mono output directly into the SIO Audio Input pin via a resistor mixing circuit.

At first I wasn't sure that this would work and actually provide good quality audio output, but after connecting it up to my LG 55" HDTV and Sony Sound Bar via a RetroScaler-2X video converter I was soon won over by the sheer clarity of the highs and the dynamic bass that this system combination was producing.

Luckily there was still a small fragment of real estate left inside the 576NUC+/NUCplus4 system that allowed the MIDI player to be added as an extension of the original FujiNet Module PCB.

PCB TOP VIEW






At the same time, an independent 3.3V regulated supply was added for the FujiNet side of things in order to correct some drop-out issues in FujiNet's operation that had been seen with the previous version.

Using the MI-PIC chip (PIC12F1572) incorporating the MIDI-CNTRL firmware to interface with the M5STACK MIDI-Synth module, adds a full MIDIMATE compatible connection scheme, as well as the ability to play an embedded start-up MIDI sound file if so desired.

1. 31,250 Hz Synchronized MIDI-CLK tied into the SIO-CLK-IN pin.
2. SIO-MOTOR enables the MIDI device to be on the SIO bus.
3. Power-Up MIDI Intro tune is possible, same as other Mytek SIO2MIDI devices.

On item 3, currently three modes are offered in the firmware download, Silent, Atari, and MULE. I'll be experimenting down the road with the possibility of adding a more traditional computer start-up sound, to be both short in duration and subtle (with a low volume level).

New FujiNet/MIDIplay module schematic:

EDIT (2/1/2025): Until such time that the official online FujiNet firmware has been updated past v1.4, the zipped file: fujinet-ATARI-v1.4.1_CKI-TEST.zip which is available in the NUCplus4 downloads section needs to be flashed for proper MIDIMATE usage. This file is part of the total firmware download file: NUCplus4_firmware_all.zip


Well that wraps it up for this post.

- Michael

Well lot's of things happened over the past 3 months.

• The NUCplus4 Project got released
• The UGV got a new, better, revised version released called the UGV-II
• I was in the hospital for 3 days because of massive blood clots in my lungs
• The 1200XL-1MB Project (a 1088K SRAM upgrade) got started

NUCplus4
This got released on September 21st 2024 nearly 3 months ago, and there have been several people that jumped right on it and are building their own (Marek, LarryL, remowilliams, Panther, Jfcatari).

There were a few small issues that popped up, such as the solder pad holes for the battery holder being too small, and the FujiNet module's 3.3V supply needing a larger capacitor. But all in all things went pretty smoothly. I also introduced a new beta version of the TKNUC1MB firmware on November 15th, with a download at AtariAge in the World's Smallest Atari 8-bit forum thread (LINK).

EDIT: The new firmware now works very similar to the 576NUC+ original firmware, and only brings up the A8PicoCart aspect when you specifically want it via the F6 key. The 576K vs 1088K RAM selection is still automatic, being wholly dependent upon whether one of the internal Language/Game Slots is active. Yes I'll need to update the operating manual datasheet, and that will happen eventually.

I haven't updated the files yet on this website, but that'll hopefully be happening soon.

And probably worth mentioning, the SD Push-Push Socket P/N: RSMT-2-MQ-WF went obsolete soon after the project's release. Unfortunately there is no drop-in substitute that I've been able to find, and when it went obsolete it completely disappeared from the likes of Digi-key, Mouser, and Newark. So for those contemplating this build, you'll need to source this as a surplus item from eBay or AliExpress, with the cost being higher.


UGV-II
I wasn't 100% happy with the original UGV, and finally decided to do something about that. Thus the UGV-II was born.

Improvements...

1. Better quality video than even the 576NUC+, being on par with the latest UAV.
2. Non-interference with stock video outputs.
3. No modifications to Atari motherboard, other than the GTIA needs to be in a socket (W2 jumper is a non-issue).
4. Simpler and easier build for a DIY person than the previous original UGV, being mostly THT components this go around.

This got pre-released at AtariAge only 3 days ago (LINK), and will eventually make it's way over here (I gotta lot of changes to the UGV webpage in mind).


I Was in the Hospital for 3 Days
Yep you heard that right, due to a genetic deficiency my blood began clotting at an unrestricted rate and got to my lungs making it very difficult to breathe. My brother has a similar condition and went through this 23 years ago. For some unexplained reason my susceptibility to this took much longer to kick in. Anyway I got on top of it in the nick of time, and I'm doing fairly well now without any permanent damage.


1200XL-1MB Project
During my recovery I was getting a little bored, so I started a new Atari upgrade project for my 1200XL. That being to replace the noisy DRAM and its associated glue logic with SRAM instead. I called upon Juergen van Radecke (AtariAge: tf-hh) to help me out with this, utilizing a variant of his NUCplus4 1MB EMMU jed.

The new memory upgrade will piggyback 4 chips on the 1200XL: PIA, SALLY, MMU, and the 74LS138. From these it will get all the required connection points, and thus be a totally solder-less design. The prototype layout is complete, and sample boards are on their way from JLCPCB in China.

Oh did I forget to mention that this is a switchable 64K, 576K, 1088K upgrade. It's based on a RAMBO banking scheme, so the only downside is that it doesn't have true 130XE compatibility like the CompyShop banking alternative (more info on that HERE). However most programs, demos, and games never supported the separate Antic access of a 130XE, with the only examples being counted on one hand.

So that wraps it up for now.

Hopefully see all of you in the New Year.

- Michael

NUCplus4 Brief Description...

This daughter board is meant to expand the basic 576NUC+ miniature Atari computer system with a multitude of new abilities. Four at any given time to be exact. Go here for more INFO.

Assembly...

This is pretty much a through-hole board in most regards, with the only exceptions being the the Push-Push SD Card socket and the optional FujiNet Module's ESP-32 which has a castellated surface mount configuration.

So just like most such boards, it's normal to start out with the low profile components first such as the resistors followed by the capacitors, and then move into the larger ones. I'm not going to go into a lot of detail regarding this, since I'll be assuming that whoever undertakes this project from a DIY aspect already knows how to assemble and solder a PCB.

Let's get into the more critical stuff, with the first being the installation of the pin-to-pin male headers for piggybacking the PLDs on the 576NUC+ board.

In order for the NUCplus4 daughter board to sit parallel to the 576NUC+ board, these pin-to-pin headers need to be absolutely flush as possible with the underside of the NUCplus4 PCB and perpendicular to it (specifically the shoulder on the pins should be flush with the PCB). To insure perpendicularity, temporarily plugging in one machine pin socket will maintain proper alignment. These will get removed after the pin headers have been soldered in place on the top side of the PCB.

Here's what that'll look like.

After soldering the male pin headers, trim all the protruding pins inside the IC socket footprints as flush as you can with the top of the board (good quality side cutters should be used for this).

Now insert the sockets for the PLDs, and after removing the temporary alignment socket on the bottom side, solder those in as well. This will be a bit tricky, and a soldering iron with a long skinny conical tip really helps.

Now you will be ready to solder in all the remaining sockets and headers. I suggest doing it in this order, so that you don't block your access.

1. Machine Pin socket for U1 (make sure U1 is pushed all the way in with its shoulder slightly protruding from the bottom of the board).
   
2. Now insert and solder all the rest of the sockets.
   
3. Insert SIO extended male pin header (P1) from the bottom side of the board and solder it from the top.
   
4. Insert remaining headers and components and solder in place. Wherever possible insert devices (Pico Module and FujiNet Module) with their male pin headers in place to hold alignment of female headers before soldering.
   

With all the soldering done, it's now time to install the necessary number of piggyback machine pin sockets for the PLDs (2 sockets each) and U1 (3 sockets). The final stack up should look like this.

The completed assembled board should look like this when you are done.

Three chips will need to get moved (U3 SRAM, U4 MMU, U5 EMMU) from the 576NUC+ to the NUCplus4. The EMMU will need to be re-flashed with the 1024K jed.

Mods...

There's a modification that needs to happen before plugging the NUCplus4 into the 576NUC+, and that has to do with the top clearance of the 576NUC+'s 8-Pin DIN A/V jack. It needs to have some of the plastic filed off (mainly the bump towards the rear).

It'll also help to trim off the pins on the rear most row of the PLD socket with side cutters after soldering.

Plug in all the required chips after flashing any that require it, and be sure to re-flash the embedded TK-II chip in the 576NUC+ with the NUCplus4 specific firmware (consult the Datasheet for more information about this)

You should now be good to go.

- Michael

I got side tracked once again the other day, and found myself studying some posts on various websites about MIDI-CAR and it's player. I had seen some things about this a couple years back, but at the time it appeared to be focused on a PBI based hardware device only. And because my focus had been centered around SIO based MIDIMATE devices, I wasn't all that interested. However when I was having a discussion with AtariAge member flashjazzcat and the subject came up about how it would be nice if there were a new and better MIDI player on the Atari 8-bit, AtariAge member PeBe popped in and said MIDI-CAR now had an SIO driver designed for MIDIMATE and its clones, and that I should check it out.

Well long story short, I did check it out and I was quite impressed at what I saw. So much so, that I decided to package it in an ATR and put it on my MIDI page as a download to take the place of that less than desirable MIDIPLAY program.

MIDI-CAR is a full featured player. It accommodates multiple drives, and works very well with SpartaDos and SDX, as well as other DOS'es. The interface is very intuitive to use, and it has an easily accessible help screen that can be viewed anytime for specific command shortcuts, and brief descriptions of what they do.

This player also fully supports the MIDI-CLK output as generated by MIDIMATE and compatible SIO2MIDI devices for proper syncing and timing, something that MIDIPLAY did not do.

However in my testing I ran across a problem with that last aspect when trying to launch the player from FujiNet. It seems that an issue has existed with FujiNet's firmware which has been pulling the SIO CLK-IN line low during its idle state, and holding it there. This defeated the MIDIMATE's MIDI-CLK output which also shared that same SIO pin. The end result was that MIDI-CAR was not able to actually send MIDI data to the end device, thus there was no music being heard from a connected synthesizer. Luckily AtariAge member mozzwald got right on the problem and very quickly provided a test version containing a fix. Since that worked, we'll be seeing an update coming soon in the next FujiNet firmware build to come (V1.4 and before will exhibit this problem). Until that update occurs, here's a link to the patched version of the firmware.

---------------------

This MIDI player diversion gave me renewed interest in MIDIMATE devices, and I finally found time to upload some of the MIDI related stuff from previous contributors like AtariAge members Montezuma and Fierodoug5 in the form of new firmware and a new 3D printed case. Montezuma provided a SILENT "no intro" and MULE theme music version for the PIC MIDI Controller, and Fierodoug5 customized one of Mr Robot's 3D case designs for the SIO2MIDI-S2 system. Check out the MIDI page for these updates.

That covers the MIDI changes and related innovations for now.

- Michael

The original 576NUC+ case design was created by Steve Boswell (AtariAge: Mr Robot) who later released the STLs to the open source community, which I was able to modify to suit this new incarnation. This was also made possible through the use of a free online 3D CAD application called TinkerCad, a simple to use but very powerful 3D design tool.
 

New 3D Printer

I recently graduated to the Bambu Lab A1 mini 3D printer, and can now do some seriously good prints.

Previously I had been using an AnyCubic Kobra Plus that I picked up for ultra cheap as a customer return via eBay. It was good for getting my feet wet in 3D printing, but I got tired of constantly having to tweak all the settings in order to get good prints, and quite frankly the Bambu blows it away. And now I can do multi-color printing the easy way.

So the cases you see above are of my final design made on the Bambu printer.


3D Printing Station Update

I had to do some rearranging to make things fit into the allocated 3D printing station space in my shop, but in the end I think it came out quite well. And I also got serious with my filament storage, opting to use sealed containers with desiccant packs inside.

HeatSets are Out

In the previous 576NUC+ case design, the upper and lower halves depended upon heat set threaded brass inserts for the screws to screw into. However I wasn't thrilled about using these since they are very dependent upon correct insertion to avoid cross-threading issues. So in this new case design I've gone with screws and nuts, with both being recessed into the case halves, and black in color to make them virtually invisible.

I sourced these from McMaster-Carr, but probably something equivalent could be gotten at your local hardware store, not requiring a minimum purchase of 100.

P/N 91249A618  Black-Oxide 18-8 Stainless Steel Pan Head Phillips Screw, 4-40 thread, 1-3/4" long, pack of 100

P/N 90328A101  Black-Oxide Zinc-Plated Steel Locknut, 4-40 thread, pack of 100


Got Feet?

On the bottom of the case there are 4 circles showing the location of the rubber feet (Clear Vinyl actually). These reference circles were sized at exactly the same diameter as the feet produced by EverBilt which can be purchased either from Amazon or Home Depot.

P/N 158 724 1/2 in. Self-Adhesive Vinyl Surface Bumpers, 16-Pack


- Michael

Previous Post

C64-VGATE for Short Board
Today I finally had a chance to test a PAL version set-up in a 250469 Short Board that I converted from an NTSC 8562R4 VIC-II over to a PAL 8565R2.

It works!!!  Including using the same VGATE firmware and the same component values as the NTSC version.

I was able to boot up and play the game Turricon in all of its PAL glory, and it looked quite good. 

Initially when attempting the installation of the RF Modulator Replacement Interface PCB into the Short Board I encountered a couple of issues involving physical fit.

Update: May 2nd, 2024  Good news! I took a different approach to assembling the PCB and discovered that it could be made to fit without issues.

After mounting the motherboard with one mounting screw between the two existing DIN jacks in the C64C case... you can then set the RF Modulator Replacement PCB in place with the two bottom 4-pin and the single 2-pin support headers. Then adjust it to fit flush with the inside back of the case. After making sure that the board is pressed down and even, solder at least one pin on each header to lock in this alignment.

Note: the other 2-pin support headers on the left and right side are not required and should be left out.

When you remove the PCB you'll see that the support headers are slightly angled - this is perfectly fine.  Note: an extra piece of header insulator block is used on all the support headers as an additional spacer. I'll probably make an adjustment on the final gerbers to allow these to be straight up and perpendicular with the PCB.

With the motherboard out of the case, use a stepped-drill to enlarge the RF output hole to 9/16" diameter. Then with a round file, create a U-shaped slot in the rectangular channel switch hole which will allow clearance for the 3.5 mm jack. This is a very minimal modification to the case, and could be reverted to the original RF modulator with hardly anyone noticing the case changes.

If everything is correct, then you should see the result below.

Assemble all of the required components into the PCB, and then mount and solder it to the motherboard.

When I mounted the MAIN C64-VGATE PCB into the VIC-II socket, it was friggin tight as hell !!!  So I de-soldered it and replaced it with a 40-pin machine pin socket instead, which worked much better.

I didn't encounter this difficulty in my Long Board installation, so it appears that my Short Board used a different socket having very tiny holes.

This could be problematic for other people wishing to install one of these C64-VGATE boards in their machine, assuming it too has the same socket issue.

Since I'm feeling pretty good about the MAIN schematic, here's version 1.1 for download...

Nice to see this work without having two different versions of the firmware, and with the same values that work for both the NTSC and PAL HMOS VIC-II chips. personally I've experienced less issues with sourcing the HMOS vs. NMOS VIC-II chips, and found them to produce a very clean picture, while giving off considerably less heat. Since my C64-VGATE MAIN board can also serve as an HMOS to NMOS adapter, I'll be sticking with HMOS chips for all of my video upgrades.

- Michael

Previous Post

I have a few projects in various states of completion that have all been put on hold, or that have experienced limited progress over the last couple of months. This has a lot to do with needing to shift gears and applying most all my time towards my 'real' job which makes me money. I don't foresee this changing over the next month or so.

Here's a list of unfinished projects that are in the queue...

1. C64-VGATE: 90% completed, presently undergoing NTSC testing and final component selection. Also awaiting PAL testing. Not sure if this will see a public release, but if it does, then I need to possibly create a BOM and update the schematics to reflect any changes.
   
2. 576NUCplus4: 80% completed, need to correct boot-up behavior issue with the FujiNet module, and finish up BOM and schematics needed for release.
   
3. Heat Load Controller: 50% completed, cost of the custom aluminum front and rear panels is holding things up, as well as the actual need for this device which is predicated by my real job requirements.

I try to squeeze in project time for items 1 and 2 wherever I can, but it's very limited at the moment. And item 3 is not aimed at general consumption, being something that might prove handy for my real job as a specialized test instrument, so currently its priority is set very low.

- Michael

It's been a busy few weeks for me, so I wasn't able to post an update on this project until now.

About 2 weeks ago I was able to assemble one board set with an HMOS 8562R4 VIC-II chip and installed it in my 250407 Long Board, using it's built-in NMOS-to-HMOS configuration jumper and special piggyback socket.

After some initial experimentation, I settled on what appeared to be the best component values, including figuring out a way to boost the video output all the way up to 1 V P/P without causing any shadowing when bright colors were being displayed, something that I had previously seen during earlier attempts to increase the video to that same level.

EDIT 4/26/2024: I discovered that my scope wasn't accurate with the probes set to x1, but was when set to x10. So because of this I ended up pretty much reverting to my original values to achieve a 1 volt video signal. However I did do a few other adjustments to better standardize the chroma level.

I was also able to compensate for some thermal drift issues that caused misalignment of the VGATE black level with the one generated by the VIC-II chip by changing out several resistors from 5% Carbon Film types over to 1% Metal Film types instead. Metal Film resistors have a much better temperature coefficient of resistance than carbon film types.

Overall the video output of the C64-VGATE video board is quite excellent, and the VGATE technology eliminates the white line that's usually seen on the left side of the image when viewed on newer HD monitors. However in order to achieve the best results it did require some additional timing adjustments in the VGATE firmware.

A nice side effect of eliminating the white line was that my cheap S-Video to HDMI converter was able to properly do the conversion without weird color and contrast issues it previously suffered from. I believe the reason for this improved behavior had to do with the white line causing confusion as to what the black level really was, because it occurred so soon after the color burst signal. With VGATE active, there now exists both a proper breezeway and back porch in the video output, something that was lacking in the original VIC-II output. And apparently my HDMI converter likes it much better.

Keep in mind that this upgrade is much more than just the elimination of the white line. It's also meant to improve the video output quality utilizing triple shielding, a higher quality video output buffer, and by breaking out the S-video into a more standardized connection scheme. At the same time, there is also provision for stereo audio output, or composite video, or LumaCode video assuming the proper upgrades are also present. These last signals are broken out to a separate 3.5 mm jack, and with the addition of a simple RCA 'Y' adapter can be connected to standard RCA inputs.

Soon I'll be updating both the schematics and a download for the firmware reflecting these changes.

I also got some HMOS PAL VIC-II chips, so I should be able to see how this improved video system works for PAL as well.

Hopefully my next blog post will cover much more detail... stay tuned.

-Michael

Previous Post (Next Post)

Complete C64-Vgate Video Board Set Installed in Long Board 250407