Silent Q

Azog's little slice of the world. Whee.

Atari 2600 composite video mod

Posted By on July 19, 2014

This has been sitting in my “to-do” list for a while, so I figured I’ll get off my lazy ass and take care of it.

This is an Atari 2600 video mod to display composite video, rather than the RF video. There is plenty of information on these mods, but I opted to pick up a kit from ebay. Other than the PCB, chances are I had everything in my junk pile, and I could have dead-bugged this but what the heck… I won’t link the ebay auction here, but if you’re interested, it was auction #300592126324.

Installation was fairly easy, if you’re comfortable with a soldering iron, but I decided to make a day job out of it, so this took me about 4 hours from start to finish. Here is what the 2600 board looked like before I started to work on it.


If you’ve never disassembled a 2600 before, they’re pretty simple. The first step for this mod is to remove or disable the RF modulator, which is the silver box in the lower right. There is a transistor which also needs to be removed or disabled, but it’s hard to tell from this picture where it is.

The installation instructions just mention breaking off the pins, but I wanted the RF modulator out, so I desoldered it and the transistor.


If you look at the zoomed picture, there is a missing transistor above the coil/choke to the right of the middle chip. As far as I understand the mod circuit, all we are doing is removing the RF modulator and adding a new transistor to amplify the original video, making it suitable to feed to a composite video input.

The mod kit is just a handful of parts. This is one of the easiest mods; there are other mods out there. I even think I recall an S-Video mod, but I opted for composite. It’s technically just a minor improvement over RF. So why composite over S-Video? The mod was obviously easier, and did not make a radical alteration to the Atari 2600.


Follow the easy directions and in a short while, ready for testing. I’m very pleased with myself. This is one of those projects which required drilling holes and I actually made them uniform in spacing and alignment. The testing requires tweaking the color output, which is done via the large pot to the left of the middle chip. I used Pitfall.


Fixing a cold solder joint later, button everything back up, and all looks well.


I did have presence of mind to take a picture of Pitfall before the mod:


And after:


It might be hard to tell in the picture, but there is a noticeable improvement in video quality. Mostly is the lack of noise.

I had a moment of melancholia during this process. Not in the typical “old man” way of “Back in my day!”. I wonder what the Atari designers and engineers would think today, knowing that over 30 years later, there are still people who play these systems. While I’m sure none of them thought they’d crash-n-burn as hard and fast as they did, did they think they’d still be around 30 years after; did they think people would still be playing the venerable Atari 2600?

I’m still a gamer, even at my age, so I was thinking, what about systems like the Wii U, etc, which are so dependent upon an online infrastructure? If the companies stopped supporting these systems and games, would they still be playable 30 years from now? Not talking about MMOs, I’ve seem my fair share of MMO deaths. What about EA, as horrid as they are? Do they think beyond the next quarter shares reports? I doubt it. When it’s no longer profitable for them to maintain their games servers, they’ll shut them down, and the games will die. If a person engineers a private/pirate server to keep playing those games, the company would undoubtedly bring full legal action against them, if it were known.

Of course, the NES and SNES are still popular systems, with playable games, even now. Where will the games of today be 30 years from now? Will something like the original Xbox ever achieve the state of retro? I doubt it. Much of the online infrastructure was terminated years ago. Perhaps some of the games are still playable, but there is sure to be a lack of functionality without the backend support. Oh, and for the record, I don’t count “virtual console” games, even tho I own quite a few on my Wii U and 3DS. And that opinion is definitely the “old man” in me.

Not all progress is good.

“Building” Grant’s multicomp FPGA computer

Posted By on April 13, 2014

Somewhere, probably via Hack-A-Day, I ran into Grant’s multicomp pick and mix computer. It is basically a pick-n-choose 8-bit computer implemented in an FPGA. Select a variety of system options, from a 6502 or a Z80, memory and so forth. Build and run. I put the word “building” in quotes here, since the build is pretty basic.

What the hell, it looked interesting and easy. My first foray into programmable logic stalled and failed.

First thing was to acquire the FPGA board, a EP2C5T144C8N Cyclone II FPGA mini board for about $20. Once I had that in hand, I realized I needed a programmer, so it was back to eBay to pick up a USB Blaster clone for $10. Since this was two separate orders, each from a (different) vendor in China, it took over a month for them to arrive…

Once I finally had the hardware, I downloaded the free version of Altera Quartus, and stepped thru Grant’s document one at a time. I selected on of his suggestions: a Z80 with 4k RAM and serial interface. Copy-paste the relevant selections into the FPGA project, with the only change being for 9600 baud (the code is at 115k baud).

With little confidence in myself, I wired everything up as documented. The USB Blaster is connected to the (a?) JTAG port; the serial port is connected to a 3.3v USB serial adapter. And I also hijacked 5v VCC from the USB adapter. Connected the USB serial port to my computer and open a terminal window on the correct serial port at the selected speed, and because it was getting power from the USB port, the FPGA board started its demo project, blinky LEDs.


In Quartus, I hit “Start Compilation”, and the only error was due to a missed semi-colon during copy-paste, but once I fixed that, it said the compile was successful. Well, now comes the acid test, and I opened the programmer and off it goes. Before I could blink my eye, the term window gave me the sign on screen!


In all seriousness, I did not expect it to work the first time. Now it’s time to mess around, maybe try some of the other configurations, IO devices, or even external RAM and try CP/M. It looks also relatively easy to add VGA and keyboard. At the moment, I can’t figure out how to permanently program the FPGA. When it loses power, it goes back to the default blinky LED demo.

I tried to mess with programmable logic a couple of years ago, but it is still a mystery to me. Getting documentation is an exercise in your search skills, as I really haven’t found one “clearing house”.

I was going to bitch, but I decided not to.

Atari Mega STe

Posted By on February 8, 2014

This is something that has been sitting in my background queue for a while, and now I’ve finally decided to tackle it. I might have mentioned this machine in passing before. Insert the warning that there are Lots of Images Ahead.



Atari Falcon030 & NetUSBee Ethernet

Posted By on February 1, 2014

Lotharek, from whom I purchased his MiST computer, has started shipping his version of the NetUSBee and I finally got my hands on one. I’ve been waiting/wanting an Atari Ethernet adapter for some time, but finding one was not easy. There were several options but most of them have been out of production for several years. The designs for the NetUSBee were released for free, but getting those designs to finished project would have been cost-prohibitive for a single-shot run.

If you’re not familiar with the NetUSBee, it’s an Ethernet and USB adapter for the Atari ST class of computers. The Lotharek version was shipped with a nice enclosure:


The front jack is the Ethernet port and behind that are two USB ports. The USB is secondary to my goals, so I have not downloaded the drivers yet but the USB ports will will be useful for using a USB mouse, as the Atari brick mouse is hideous.


So first I’ll plug the cart into the Atari Falcon and attach an Ethernet cable to my router. Pay no attention to the flat ribbon cable that runs underneath; that is the cable to attach to the ScreenBlaster video enhancer. But you can see the Ethernet link light is active, which is always a good start.


For starters, I am going to play with the TOS version of things. Later I’ll try setting up the MiNT/MultiTOS version.

Software installation was marginally straight-forward. Download the STING archive from Lotharek’s site, which contains a number of files and folders (the screenshot is from 7ZIP on my PC but the files can be transferred directly to a PC formatted floppy and read on the Falcon):


For anyone familiar with TOS, the folder structure should be familiar:

  • The AUTO folder contains the TOS driver for the NetUSBee
  • CPX contains the X-Control panel applets used to configure the driver
  • STING contains the configuration files

There are other files but are not of immediate need. Once the files are copied to their proper location and the Falcon has been rebooted, the X-Control panel has several new applets.


Configuration is done with the STinG Port Setup. The others provide drivers for UDP, ICMP, etc, but should be OK as default. Opening STinG Port Setup let’s you choose the IP address and netmask. This screen shows a dropdown list of the other options STinG provides (Modem and LAN) which would be useful for using over a modem, such as SLIP (Serial Line IP) or PPP (Point to Point Protocol), which are the protocols we used back before Ethernet became ubiquitous. Behind the dropdown, but still visible, is the IP and netmask, It is important to make sure the Active box is enabled and the configuration is saved in the STING directory as STING.PRT.


In the same applet, select the General downdown for Ethernet, and it should show you the MAC address, which indicates everything is working. Again make sure the Active box is checked. If no MAC address appears, then something else is wrong. The NetUSBee does have the MAC on-board, so there’s no need to fudge a MAC address, but rather to stop and make sure the cart is inserted properly and the driver is loaded.


If your network IP scheme differs, you’ll probably have to edit the ROUTE.TAB file in the STING directory.

Once that is done, I rebooted the Falcon, but was not able to ping it. I don’t know why, but at this point, it was getting late, so I powered everything off and picked it up the next day. When I powered it back on, ping was working as expected. The ping times are not the best, especially considering I am on the same local Ethernet, but I guess that should be expected, all things considered.


Now that I know the basic IP transport is working, it’s time to try a web browser, in this case, the CAB browser. You need an overlay for CAB, which I found here. Even tho it says STiK, it’ll work for STinG. Going back 20 years in memory, I think STiK is the predecessor to STinG. Once I downloaded and extracted the CAB archive, and copied the OVL, I had to create a cache folder in the CAB directory. When you first start CAB, it asks for this, so create the cache dir first. Otherwise if you try to browse something, it won’t work.

So open a URL, here I chose the “retro” edition on Hack-A-Day. I don’t know if they’re still accepting submissions for this, but it was appropriate, and I’ll send it to them anyways.


There’s other software to be found, like mail or ftp clients which should be useful to download stuff directly to the Falcon, rather than using floppy disks.

Commodore Flyer modem enclosure

Posted By on December 26, 2013

Stumbled across this one day on comp.sys.cbm. Yes, usenet isn’t dead.


It is a very nicely machined enclosure for the Commodore Flyer modem, which until now, had been living inside the anti-stat bag it was shipped in. Apparently a one-off project by a group/person called MarchLabs. I love projects like this, and even more so when it’s something of high usefulness. I wish I could fabricate enclosures, but I lack pretty much everything necessary: the CNC for starters, and the skill to draw in a CAD program. You can see how it’s been milled.


The Flyer sits nicely inside, and a rubber boot for the reset switch:


Everything lines up:


Four rubber feet to hide the screw-holes; I doubt I’ll need access to the internals. And a transfer sticker of the Commodore chicken-lips.


Unfortunately, sold out…

Commodore PET web . . . server?

Posted By on August 16, 2013

So is this the first web server running on a Commodore PET 4032?


Retroswitch released a new firmware for the Commodore PET Flyer Internet Modem which allows for inbound connections. So, of course, the first thing to do was was to whip up a crude web server.


The BASIC code is simplicity itself:

First, listen for a connection on port 80. A loop between lines 30 thru 60 reads the connection status (stored in variable D). When D=1, a connection is made.

Next, grab out the IP address, so I can display it both on the console and on the web page, and then spew out the raw HTML. Close the socket, and start all over again.

   10 open2,7,2,"listen:80"
   20 open7,7,15
   30 print#7,"n-s:2"
   40 input#7,a,b$,c,d
   60 if d=0 goto 30
   70 print#7,"c-i:2"
   80 input#7,a,b$,c,d
   90 printb$
  100 print#2,"<html>"
  110 print#2,"<head>"
  120 print#2,"welcome to a commodore pet 4032 web server!"
  130 print#2,"</head>"
  140 print#2,"<p><b>welcome to the"
  150 print#2,"world's first"
  160 print#2,"web server running"
  170 print#2,"on a commodore pet 4032!"
  175 print#2,"</b>"
  180 print#2,"<p>your ip address is ";b$
  190 print#2,"<p>"
  200 print#2,"thank you for visiting"
  205 print#2,"</html>"
  210 close2
  220 close7
  230 goto10

Unfortunately, I cannot run this “live” for a few reasons… One, is because the PET is set up in my general work-area, which I use for a variety of purposes, and can’t really dedicate this to run full-time. Second, I’d be concerned about screen burn, but I guess I could put a cut-off switch on whatever line provides the CRT high voltage, but that’s kinda nasty.

Dialight 704-1549 based display

Posted By on June 9, 2013

Some time ago, I picked up an interesting display module based around a Dialight driver:


There are five modules, each with a Dialight driver and 7-segment LED display. Each module is separate, and you can remove the endcaps to remove the modules. I guess you could remove modules and cut the chassis down to a smaller size, or even theoretically add modules but you’d have to embiggen the chassis. Either way, it looks like a quick/cheap method for a production house to provide a product for various customers who might require different quantities of displays.

It was easy to find the datasheet, and just as easy to match up the pins with the card edge connectors, which you can see via my handwriting on the sheet under the display module.


Not sure what, if anything, I’ll do with them. Standard TTL logic, consistent pin ordering, and what appears to be 0.156″ card edge would make it fairly simple to interface to something.


But the question is, what? I’m kinda short on ideas. The whole thing is vaguely reminiscent to the TIL311 displays I played with in the past, but I don’t know if I wanna do another clock.

1541 write protect mod

Posted By on June 7, 2013

This is a why-not project. I felt like installing Ray Carlsen’s 1541 write protect mod, a switch to enable/disable the write protect on a 1541. It’s pretty easy, but since I have the 1541C, I got a little creative. The original photos detail a non-C version of the 1541, but it was still simple enough, taking less than 30 minutes from start to testing:


P112 and GIDE (revisit)

Posted By on May 29, 2013

This is a project that’s been kicking around for some time, and I finally got up the gumption to have another crack at it.

I built a P112 some time ago, and then added the GIDE. This was before the Kickstarter campaign.

After building everything, I got it mounted in an enclosure that was originally an HP drive module. The GIDE mounting orientation is not going to remain as in this photograph. I have ordered some 90 degree headers so I could mount it horizontally, and be able to (hopefully) put the cover back on the whole thing.



Commodore 64 cartridge proto board

Posted By on April 22, 2013

I wanted to experiment with the Commodore 64 cartridge slot, but not having a “proper” edge connector, or proto board, I broke down and drew up a simple board that I sent off to BatchPCB.


What you can’t see here (and neither can I, because I drew the traces too narrow at 6 mils) is that every row of three vias are connected. There is a power rail going down the left side, quote noticeable (gnd and vcc), but the grid layout didn’t work like I hoped… So I manually drew a marker down to visually separate the grid.

Each edge is connected to a row of two vias directly above the edge connector. They’re labeled, but again, I used too small of a font to really read them. But the upper edge connects to the closest two rows, and the lower edge connects to the third and fourth row.

This should make it easy to layout a variety of parts. For which I have an idea, being the whole point of this project, but which I’ll defer for a later post, as I strive to overcome the disappointment in myself for not thinking clearly enough while laying out the visual markings.

Given that the specs for the C64 edge connector is well know, this is nothing stupendous, but I’ve not really come across anything in this specific configuration. I’ve picked up socketed cartridge carriers, but nothing quite generic like this. I drew it in EaglePCB, so if anyone is interested, I can post the project here. Perhaps after I widen the traces and embiggen the font…