Pi1541 IO Adapter

Posted on May 20, 2018 by Bigby

Update 2018-05-25: Now that revision 1 is confirmed to be working despite a couple of minor issues, here’s the rev.1 Gerber files for download. Bear in mind though that the improved 2nd revision is under development and will be available soon!

Two weeks ago, there were exciting retro-news on the Lemon64 board: Gorack – aka. Steve White – released the first version of his Pi1541 that he had been working on for quite some time. “Pi1541 is a real-time, cycle exact, Commodore 1541 disk drive emulator that can run on a Raspberry Pi 3B (or 3B+).”

I was curious and wanted to give this a try, but I also wanted proper wiring. So I created my own version of an extension board for the Raspberry Pi. (Not a proper “HAT”, that would require an eeprom and other things.) I then ordered a small prototype batch because others were eager to try our new retro toy, too.

I received the PCBs on Friday after some unfortunate delay at the German customs and by now the first board is assembled and seems to be working fine!

There are two minor issues in revision 1 that I will address in revision 2: Continue reading →

Retro Repair, Addendum I

Posted on April 29, 2018 by Bigby

In my last post I repaired the mainboard of an old Commodore 64 I had retrieved from the attic. After replacing quite a few components, the board was working again for most practical purposes. One issue remained to be investigated though: under certain circumstances, some characters on the screen would change their color seemingly at random.

Random characters changing their color.

This was already visible in the diagnostics output but turned up again later in a graphics adventure I tried. Besides the VIC chip itself, the static color RAM U6 or the 4066 quad switch logic IC U16 seem likely causes for this problem. Continue reading →

First Retro Repair

Posted on April 15, 2018 by Bigby

Commodore 64 “breadbox”.

Recently, I retrieved a Commodore 64 “breadbox” version from my parent’s attic that was given to me by a friend in the early 90s. As I recall, it wasn’t fully functional even back then. It would halt as soon as a program tried to play any sound. But when I connected it now and powered it up, all I got was a black screen.

The broken ASSY NO. 250407.

I took it apart completely, even the keyboard, in order to give the case and all the mechanical parts a good cleaning. Then I went on to see what I could do to fix the “ASSY NO. 250407 REV.B” motherboard that I found inside. Continue reading →

SyncFix64 v1.1

Posted on January 19, 2018 by Bigby

Following the first prototype of the LM1881 based SyncFix64 I made a few minor changes, improving the schematics and layout. Then I was ready to order the first batch of properly manufactured PCBs. The boards took a little over two weeks for production and shipping.

Continue reading →

Fixing WifiModem64 Version 1.0

Posted on January 11, 2018 by Bigby

As hinted at earlier, I made a couple of mistakes when designing version 1.0 of the WifiModem64 and they will be fixed in version 1.1.

Still, with some minor manual modifications, those first boards are still usable. In short, RTS must be connected to WeMos D7 instead of D8 for the ESP8266 to boot reliably and the WS2812 LED must be connected to WeMos D5 instead of D0 if you intend to use it.

These are the step-by-step instructions to get WifiModem64 V1.0 on line: Continue reading →

SyncFix64 Prototype

Posted on December 30, 2017 by Bigby

After the encouraging results of my first attempt to fix the composite signal from a C64, so that the cheap TFT monitor could display it, I shared the idea on Forum64 to double-check and get some feedback. Consensus seems to be that the circuit at least won’t hurt the video source. Since, in addition to that, it seems to be working for me, I decided to design a board for it in KiCAD.

The goal was to make it so small that it would fit inside the display’s case alongside the display controller, so I went for all surface mount components. To get immediate results, I created a single sided layout and etched the board myself using the toner transfer method. Continue reading →

Cheap Displays for Old Hardware

Posted on December 28, 2017 by Bigby

A couple of months ago I dug out my old Commodore hardware again and started tinkering with it – the goal being to finally try out a bunch of mods, hacks, and builds that I missed back in the day. To start with, I bought a cheap TFT display (~~new link on eBay~~, ~~even newer link on eBay~~, a little harder to get on eBay these days) for around 13€ to connect to the C64 and C128.

It was meant to sit on my work bench to e.g. quickly test a naked C64 board. It wouldn’t matter if the video quality wasn’t great. But after I made the necessary adapter cable and hooked everything up, I was a little disappointed to find out that the display wouldn’t show anything other than a black screen interrupted by an occasional flicker. I verified that the display itself was working by connecting it to a Raspberry Pi and I double-checked the cable I had made. Continue reading →

The Modular WifiModem64

Posted on December 23, 2017 by Bigby

I’ve been playing with the ESP8266 since late 2014 and it was love on first sight: so many possible uses for such a small device at such a low price tag. And very early on I thought: wouldn’t it be great to build a WiFi “modem” from this? That shouldn’t be too hard. But I didn’t find the time to pursue the idea then. When I remembered again this summer, I was not surprised but still excited to find that others had had the same idea and hadn’t been as lazy as me.

Alwyz’s instructions on how to build such a device couldn’t be easier! I followed them and it worked like a charm. For the next months, my setup then looked like variations of this:

Continue reading →

SD2IEC Revisited

Posted on December 10, 2017 by Bigby

When I discovered the MMC2IEC / SD2IEC project by chance back in 2009, it made me dig up again my soldering iron and electronic components after many years of disuse. I built myself one of those devices on a prototyping board and had a lot of fun doing so. It was the first time that I got involved with micro controllers and I learned a lot in the process.

Now, many years and projects later, I was looking for an excuse to try out KiCAD and to learn how to design my own boards using it. I had already ordered a small PCB I found on the net as a proof-of-concept to see if the Gerber files I produce would result in working boards. When they turned out just as expected I was eager to create something myself. This was the perfect opportunity to revisit the subject and make myself a brand new SD2IEC.

I wanted the design to be based on Shadowolf’s latest version but also make my own additions and changes:

The board should be able to tap into the cassette port of the C64 for power supply.
It should be board for external use with proper connectors just like my first build.
All components should be cheap to buy from Chinese suppliers.

So, this is the first prototype of what I came up with. I call it the “SD2IEC pluggable”:

Continue reading →

Project excavation: SD2IEC on Perfboard

Posted on December 7, 2017 by Bigby

The discovery of the SD2IEC back in 2009 rekindled my interest in electronics. I started this blog after I built myself one of those devices but I never got around to documenting it. At least I’d like to share the images I took during the assembly process now.