Back in Fall 2021 we met in a small village near Dortmund to have our anually retro event called "DoReCo"! Which means "Dortmund Retro Computer Treff" in german - a place, where you can have a full featured 4 day retro computer convention in a conveniant and pleasant environment. Some guys introduced a little PCB called WiC64 to bring a old fashioned Commodore C64 into todays internet. Cool !

One year later - now in 2022 - I showed up with my adaption of WiC20 , which is a VIC20 port of this now famous WiC64 . This little rascal let's you do magical things like:

LOAD "HTTPS://STRAESSLE.EU/START.PRG"

Yep, you can load all of your favourite programs right from the internet. Which is cool anyway, but wait ... I wanted to have a one-of-a-kind VIC20, something realy special. So I came up with this idea:

OK, you might say this is an C64 C, and in a particular way you might be right, but ...

Looking at the colours of the case and of the F-keys you must admit that this is no regular C64! And what does the labels say?

Commodore Spirit? Never heard about it? Never ever? Look here, and you're a bit closer to the story behind this VIC20.

Sure, it is a VIC20! My adaption of a C64C case to hold a VIC20-CR board on its inside. I had to do some cuttings here a there, but I think it came out nicely:

OK, on its side it is telling the truth about the origin of this case:

But when people walked by, they had to look closer what's going on here:

And yes it's true:

This is a VIC20 as a Commodore Spirit with the famous WiC20 module on its back to load all the programs in no time !!!

Free - Stereo - SID ==> Freie Stereo SID - Bedeutung, Information und Aufbau

Nun, der SID mit seinem markanten Sound ist legendär für das Klangerlebnis vieler Spiele und Demos des Commodore C64. Dabei ist es streng genommen falsch, von DEM EINEN SID zu reden: es sind viele verschiedene originale Commodore-6581/8580 verbreitet, zunächst MOS-, später CSG-ICs, alle mit teilweise mehr oder minder stark hörbaren klanglichen Nuancen.

C64-Wiki oder Wikipedia

Darüber hinaus sind weitere Derivate im Umlauf; diese versuchen, mittels eines universellen Controller-ICs die klanglichen Eigenheiten und Eigenschaften eines SID per Software nachzubilden und den Klang dann analog als Audiosignal auszugeben. Von einem dieser Derivate soll hier die Rede sein, dem FreeStereoSID -FSS:

Hier ein paar Worte des Entwicklers:

Der "Free Stereo SID" besteht aus den folgenden beiden Komponenten:

 *SID Sockel Adapter-Platine mit Level-Shifter und Sockel für einen
 *Teensy 4.0

welche man dann in einen C64 SID Sockel stecken kann.
Der ganze "Free Stereo SID" ist Public Domain, komplett und "wirklich" frei.
Kein Open Source, keine Fussfessel ala "General Public License (GPL)" oder dergleichen.
Man kann also damit machen was man möchte ;-)
Die Software befindet sich noch in der Entwicklung (Beta).
(Matthias)

... und den Quellcode mit ein paar Informationen habe ich, nach Rücksprache mit dem Entwickler Matthias, auf meiner GitHub-Seite veröffentlich:

GitHub

Dort ist der -aktuell noch in der Beta-Phase befindliche- Quellcode in der Version 0.1 abgelegt, der jedoch seine klanglichen Leistungen bereits eindrucksvoll unter Beweis gestellt hat (Quelle: Youtube - Screen Shooters):

In diesem Video wird ebenfalls darauf hingewiesen, dass die Lautstärke DIESES SID noch sehr gering sei. Korrekt, zu Testzwecken wurde diese reduziert, wir ändern dieses:

Nun erfahren Sie, wie diese Änderung im Quellcode umgesetzt wird und wie der Aufbau nun im Einzelnen durchgeführt werden sollte:

Hardware

Wie bereits eingangs erwähnt besteht der FSS aus zwei Teilen:

• der Adapterplatine
• einem Teensy 4.0

Da der Teensy 4.0 nicht 5V-kompatibel ist, wird die Adapterplatine mit den Level-Shiftern benötigt.

Zur Vorbereitung des Teensy wird zuerst mittels eines scharfen Cutters die 5V-Verbindung des USB-Anschlusses unterbrochen:

Dies ist wichtig, damit später beim Programmieren des Teensy die Spannungsversorgung vom C64 kommt, und damit NICHT der programmierende PC / Laptop fälschlicherweise den gesamten C64 mit Strom versorgt!!!

Damit der Teensy montiert werden kann, werden hier sogenannte

• Präzisions-Sockelstreifen und passende
• Präzisions-Stiftleisten
  benutzt und auf die benötigte Länge von jeweils 14 Pins gekürzt:

Zum Löten ist nun eine ruhige Hand, ein Elektronik-Lötkolben -besser Lötstation- und eine gewisse Reihenfolge der Montage gefragt:

1. Beginnend mit dieser Stiftleiste (links unterhalb der Platine, hier bereits verlötet, beachte die Position INNEN):
   

2. Nun folgt diese Sockelleiste (oben rechts auf der Platine, beachte die Position INNEN):
   

3. Es folgt eine weitere Stiftleiste (auf der rechten Seite unterhalb der Platine, Position AUSSEN):
   

5. ... um dann eine letzte Sockelleisten zu montieren (oben links auf der Platine, Position AUSSEN):
   

Somit wäre die erste Hürde genommen, es folgt die Montage der beiden Stiftleisten am Teensy auf dessen Unterseite, und nachdem dann die beiden Leisten verlötet wurden, können die beiden Platinen zusammengesteckt werden:

Hardware -> check ☑️

Nun zur

Software / Firmware:

Es empfiehlt sich, bereits die Arduino GUI installiert zu haben. Nun benötigt man zur Programmierung des Teensy eine zum Betriebssystem des PCs passende Extension, die hier heruntergeladen werden kann:

PJRC, Download Teensyduino

Nachdem auch diese Software installiert wurde, kann nach dem Start von Teensyduino der Quellcode geladen werden:

und die Anpassung an den verwendeten Controller erfolgen:

Damit der FSS mit einer ausreichenden Lautstärke seinen Dienst verrichten kann, wird im Kartenreiter "FreeStereoSID" die Kommentarzeichen entspechend geändert:

float sidOutputVolume = 0.25f; // Do not use more than 0.3!
//float sidOutputVolume = 0.05f; // ...0.05f Headphones Level for "Developing"

Nun den FSS in den C64 SID-Sockel einsetzen, C64 einschalten, die Firmware kompilieren und die Übertragung mittels Druck auf den Taster am Teensy starten:

Software/Firmware -> check ☑️

Nun kann sofort der SID auf Herz und Nieren getestet werden, dieser ist sofort betriebsbereit. Viel Spaß und happy hacking ...

Have fun ;-)

Building up my brand-new Commodore C64, using the Tuning-Board!

<>

Ich weiß, was Sie jetzt denken, und Sie haben Recht ...

... ein Commodore C64 ist ein alter Hut, der war mal toll, heutzutage gibt es viel, viel bessere Computer mit besseren Grafiken und Sound, aber ...
... warum sind viele, auch teilweise Jüngere, wieder wie verrückt nach diesen Computern? Weil sie Kult sind? Weil die Spiele Kult sind? Weil man 6502-Assembler mit 8-Bit schneller erlernen kann, um die Maschinensprache zu verstehen? Weil man damit Basteln kann?
Die Wahrheit liegt irgendwo dazwischen, bei dem einen mehr hier, bei dem anderen eher dort.

Aber Programieren und Spielen sind die eine Sache (Software), aber mit und am Cevie zu Basteln, also Hardware-nah, dass ist für viele Neuland (<-sic, O-Ton Angie ;-) ). Früher wurde der C64 gemodded, da war dieser Ausdruck noch überhaupt nicht erfunden. Gehäuse über- und übervollgestopft mit Schaltern, Potis, LEDs, Drehknöpfen aller Art, das war in den 80er normal.
Quelle: pitsch.de
Unverbastelte Cevies sind heute selten und werden mit Gold aufgewogen. Zum Basteln eigentlich zu schade.

Aber wie wäre es, wenn man ein altes C64-Board hätte, die Bauteile auslötet und auf einem NEUEN Board wiederverwendet? Vielleicht sogar auf einem Board, welches explizit fürs Basteln und Modding entwickelt wurde? Eines, wo man SEINEN C64 so richtig TUNEN kann? Und somit kann sich jeder SEINEN C64 zusammenbauen, ganz gleich, wie er/sie ihn haben möchte. Und ich habe es auch getan:

Zunächst werden auf der alten Spenderplatine alle gesockelten ICs vorsichtig entnommen. Die anderen werden nun in einem zweiten Arbeitsschritt mit einem Entlötkolben "geerntet". Hierzu ein paar Tips:

• Entlöten von alten Platinen geht deutlich leichter, wenn man zunächst die Pins neu VERlötet, also frisches Lot und Flussmittel aufbringt. Wer dies noch nie gemacht hat, wird staunen, wie leicht dann die folgenden Schritte fallen.
• Entlötlitze ist für doppelseitige durchkontaktiert Platinen nicht zu empfehlen. Besser sind manuelle Lötpumpen oder eine Entlötstation. Vielleicht ist im Bekanntenkreis ja jemand mit einer solchen Ausstattung.
• Nach dem Auslöten dann die Pins vorsichtig ausrichten und mit dem Lötkolben die Zinnreste abstreifen. Dann passen die ICs nachher besser in die Sockel.

Nun kann die Bestückung der Platine erfolgen, beginnend mit den niedrigsten Bauteilen:

Dannach können auch die anderen Bauteile folgen. Dem Entwickler sei Dank passen auch die dicken ZIF-Sockel nebeneinander auf die Platine, gegebenfalls dreht man die Orientierung, falls der Knebel mit anderen Bauteilen kollidieren sollte.

Und irgendwann -ja, es dauert, nur Geduld- hat man dann alle Bauteile bestückt und nach einer, zwei Sichkontrollen fiebert man dann dem ersten Einschalten entgegen:

...und tatsächlich, der 64er ist wieder zum Leben erweckt worden. Brandneu, und doch so schön alt. BTW, die fehlenden Bytes oben im Screenshot sind darauf zurückzuführen, dass das passende RAM noch nicht geliefert war und ich mir testweise einen C32 aufgebaut hatte:

Und nun kann man jedem voller Stolz sagen, dass man seinen C64 selbst aufgebaut hat und sich nun ruhigen Gewissens ans TUNEN machen. Denn dafür ist das Tuning-Board ja da.

Falls jemand die Expansionsport-Abdeckung mit dem 3D-Drucker nachdrucken möchte, die Daten sind in meinem Github-Repo frei verfügbar.

Ebenfalls findet man dort auch eine gemoddete Version für den Kernal-Umschalter, der die deutlich günstigeren Winbond W27E257 als EEPROMs nutzt, einen Soft-Reset per Restore-Taste auslöst und auch mit den LEDs spielt.

Und wer möchte, kann eine Floppy 1541 gleich mit im Gehäuse einbauen, in Form einer PI1541. Auch dies hat der Entwickler bereits vorgesehen:

Have fun ;-)

cassy

Commodore PET 2001 series - breeding and care

Okay, we all know, what we're talking about, don't we?
A Personal Electronic Transactor, short a PET, introduced by Commodore in the late 1970s.
Up to now, I recently have been working on Commodore VC20 / VIC20 Home Computer. Last weekend I got a call from a good friend telling me that I could buy a PET-Computer in a reasonable condition. The only drawback is that it's not working. OK, we have something on the screen, which means, that it isn't completely gone.

Garbage Screen - something extremely typical for the PET, some people say, it's not a bug, it's a feature! If the CPU or the memory or the ROMs aren't working, you get this message. NO, there is now hidden message behind the letters on the screen! The fact that we can see this garbage is that the TTL-logic behind the discrete character generator is working, but the startup sequence isn't firing up. And as we have learned, this can have almost half a trillion of causes: Bad CPU, bad connections, bad power, bad CIA / VIA, bad ROMs -very common-, bad RAMs - even more common-, both latter especially in the very first series with the MOS 6550 RAM chips and the MOS 6540 ROMs. But I didn't want to buy the pig in the poke. Luckily, the guy selling the machine was really very nice, so I could take a look inside the cabinet. To my surprise, it had a different board than I expected. This particular one was populated with TMS4108 DRAM chips and the much more common 2316 / 2332 ROMs. So it must be a very first Dyn-PET 2001 series. These boards later were used in the CBM 30xx Commodore machines, when Commodore had to change the name PET to CBM for the European market (Philips had already taken the rights of this name for their own Programm-Entwicklungs-Terminal).
To make a long story short, I bought this machine and couldn't wait to see it working. But it was a long and winding road from the 'yes, it's mine' to the 'mission complete' of a great looking and superbly working piece of computer history. But one by one ...
As always you have to know your enemy. So studying the schematics is essential to succeed. An excellent point to start is zimmers.net. This sounds a bit unbelievable, but IMHO you can find almost everything regarding commodore on his FTP Server. And really, here you can see that commodore had produced this very exotic computer. The assy number 320351 is correct, and it is a version with 8K and an internal cassette drive. So it must be a 320351-06 or -12, great! So I studied the schematics and -as always- checked the voltages of the power supply. Touching the connector with the probes I heard a buzzing sound and the screen became blank. Oh no! I was sure I didn't made a mistake. OK, take a deep breath, turn it off, turn it on again - garbage screen - OK - blank screen - what?

It took me a while to understand, that this is not another issue but we are stepping ahead. The startup sequence became alive - so the CPU and at least the uppermost ROM - to clean the content of the screen RAM. But there was this buzzing sound, I have to checked the connector:

Bingo! Yes, I have bad eyes but even I can see the brownish part in the red plug. and the pin header speaks the same language. So after many years the connections became bad, this heated up the connector, the connections became worse and so on .... Luckily there is a spare part inside this plug. The key- pin on the header isn't populated, but the unused part in the plug is there. You can see both of them in the picture above, one shiny, the other one rotten. After this first step I checked the voltages again, this time everything is fine. But the screen stayed blank. I took my EEPROM programmer with the corresponding 2364 adapter and read all the ROMs. No issues, all were tested fine. Still the startup sequence - garbage - OK - blank - OK - but there was no message saying Commodore Basic.
Perhaps it's something wrong with the RAM? I checked the voltages -sic- voltages!!! These DRAM are powered with +5Volts, -5Volts, and -last but not least- +12Volts. And the latter was missing! I only measured 0.2Volts, almost nothing! OK, checking the voltage in front of the 7812 reads +18Volts - fine. On its output I had +0.27Volts. On the DRAMs I had +0.2Volts. OK, I had a drop of 0.07Volts on the copper wire of the circuit board. Something is blocking the +12Volts power rail, but what? The DRAMs? Nope, they didn't warm up at all! So I traced the copper wire from the 7812 almost to the front of the board where you can find a bank of capacitors, to the rail along the DRAMs. I measured again along the trace and - wait a minute - the drop stopped at the capacitors!!?? OK OK, I'm an older guy, once again: +0.27Volts output on 7812, check, +0.2Volts at the capacitors, check, and even 0.2Volts at the DRAMs. This means the short isn't caused by the DRAMs but by the capacitors? I had a foreboding: a long time ago I had a lot of trouble with a tantalum capacitor blocking the power of a small battery powered circuit. This capacitor was short! Could it be possible, that one or both cause the shorting of power? Without blowing or heating up? While heating up my rework station I calculated: the 7812 is limiting the current to 1Amps, and we are taking about 0.2Volts, which means 0.2Watts for the capacitor. That's almost nothing, at least not enough to blow up the tantalum. I removed both of the capacitors responsible for the +12Volts and replaced them with two regular capacitors.
Keeping the fingers crossed I switched on the power: - garbage screen - OK - blank screen - OK -

My heart skipped a beat when I saw this little innocent message on the screen. But it is true - system up'n'running. Checking the keyboard - fine! But I didn't wanted to have the other old tantalum capacitors on the board. If one fails, who's gonna assure the other working? I didn't want to wait until the next of these nasty little beasts ruins my day. So it's time to heat up the iron ...

I banned ALL of them, at the mentioned capacitor bank, at the end of the power rail and even the one at the NE555 controlling the reset circuit.

While removing the flux I noticed the stained edge connectors! After the cleaning they look like new. And there as another thing I became aware of: scratched traces located at the unpopulated DRAM section UJ7 - UJ9.
Well, I read the article in The PET Paper, Volume III, Issue 8/9/10, Feb/Mar 1981, where the author complained about Commodore's way to make even more profit:

Drilled holes in the PCB, big holes, half an inch! What I got here is a different way to prevent dealers or people with electronic skills to upgrade their computer.
But anyway, that's history! And I'm happy with my new old Commodore PET. It's a little beauty, and sure: Bill Gates came by giving Jack Tramiel this nice little easter egg with the WAIT6502,1 or even more, if you like

The story behind the Commodore VIC20 names, history and why it's "The Friendly Computer"

"We Will Become The Japanese!" -- Jack Tramiel, April 1980

In London, April 1980, at an international Commodore manager's meeting Jack Tramiel surprised everyone by announcing his intention to develop and market a "$300 personal computer". A debate ensued, with several groups breaking down into pro's and con's of a low cost computer. After a while, Tramiel stood up, pounding his fist once on the table and with his deep booming voice he explained: "The Japanese are coming, so we will become the Japanese! Japanese companies had already captured the TV, radio and small car markets, and personal computers were next on their list. We have to compete with ourselves by making computers that do more and cost less, and that means breaking the $300 price barrier."

But it is possible, economically and technologically, to build such a low cost machine? Or is it too limited? Using the MOS VIC chip allowed only 22 columns, although the 8/16 colors and the sound capabilities are a benefit for the whole system. But is this enough to compete on the forthcoming fight?

"Let's build a computer for the masses, not the classes" -- Jack Tramiel

At this time Michael Tomczyk was an assistant to Jack Tramiel, and it was Jack to leave most of the key decisions to Michael – for example the name of the computer, the type of the keyboard, the keys colors and the case, the decision to add function keys and a built-in RS-232 interface beside some other ergonomics.

Jack Tramiel (left) and Michael Tomczyk (right)

And it was one of the hardest challenges to give this new friendly computer its name.
Michael Tomczyk:
For example, my original name for the VIC-20 was “Commodore Spirit” which I thought had a nice cache – however, at the last minute, my Japanese colleagues informed me that the word “spirit” in Japan does not mean “wonderful energy” or “Casper the friendly ghost” – but rather would be associated with horrid, ghastly, ghoulish things. So I went to my second choice, which was VIC, and since VIC sounded to me like a truck driver, I arbitrarily added the number 20, because 20 is a friendly number.

Most of the engineers liked the name Vixen. But that name had undesirable connotations in German, but the word VIC in the German pronunciation makes it even worse. What to do?

Well, in the end the German models (and only the German models) were called VC20. And this was very smart: The VC was used in advertisings as "VolksComputer"(the People's Computer), just like VW i.e. Volkswagen.

The Friendly Computer

And how does it come that it was announced as "The Friendly Computer"? Well, once again it was a brilliant idea of Michael Tomczyk. Reading a computer magazine he stumbled upon an advertising of Atari with the markable slogan:

Atari - Computer For People

He asked his lawyers whether such a general wording could be protected. When they told him that this was possible, he immediately had the phrase "The Friendly Computer" protected.

P.S.
Please forgive me, but I couldn't resist to make a logo for the first of all names, the Commodore Spirit, which never came to life:

And so, the story of the VIC goes on ...

A What? Workbench? We are talking about classic computer, sure?

OK, OK, not a workbench in the true sense, but some sort of a sturdy place I can start to check all the magic chips made by M.O.S. like 6502, 6522, 6560, 6561 ...
As an electronics technician I don't want to stress out these little sockets underneath the microchips ( and the chips themselves ), and sometimes it drives me nuts to fiddle these centipedes out of their habitats.

Well, what inspired me was the sight of this technical marvel of a C64 Reloaded MK2, it's like a piece of art. And yes, I liked the idea of these wonderful easy to use ZIF sockets. I would be able to swap out all my 40-leged bugs within seconds.

Let's do this with a VC20 / VIC20, and with the genuine board:

Fortunately I had an old broken VC20-CR board handy. This is an ideal candidate for the upcoming process. But this poor little guy had some issues:

OK, this gives me a wonderful win-win game. Repairing this board and making it a platform to repair other VC20 / VIC20 and the corresponding microchips.

First of all, I recently desoldered all of main microchips from the PCB, because literally none were mounted in sockets. So, after that I decided to use ZIF sockets for all the bigger ICs (CPU, VIC, VIAs, ROMs). Sometimes it is necessary to mount the ZIFs in the opposite orientation to make some room for the lever.
Hereafter it became obvious, that NONE of these microchips were broken. I tested every single one of them in a different VIC, so far everything's fine. But the board itself didn't work.
I was in parallel doing some programming on my test cartridge for the expansions port, and this showed that the cartridges ROM code was read by the cpu and executed correctly, but there was no control over the memory (RAM).

Digging a little bit deeper into the VIC20's circuit diagram it became evident, that there's a difference between the CD(ata) lines an the corresponding VD(ata) lines. Some of these data bus signals are shared between the CPU and the VIC, especially the signals to the RAM. To make sure, that everyone of the CPU and the VIC are in sync, there are several clock signals, deriving from another. So checking these clock signals with an oscilloscope gave me many working signals, but one was missing:

On FB12, which is an ferrite bead, was NO signal at all. Bingo! The clock phi1 wasn't here. This board couldn't work.
So I replaced IC UC3, and - keeping the fingers crossed - switched on the power.

TADA!
Everything's fine now! Back alive. What did we learn in that short story? Sometimes there are small parts that can ruin the day.

And finally I have my workbench with all these fancy turquoise ZIF sockets, turquoise capacitors and green power LEDs mounted on the board.

You like to see this board in action? Playing the NEW cartirdge game Cheese And Onion? Take a look here at HomeCon 53 NuVie video:

My first V(I)C20 - passed away long, long ago ...

I was probably still a young boy, maybe eleven or twelve years old, when I was impressed by the computers, games and accessories in the shop window of SHOP64 in my hometown. Staring at all these fancy things for a long time, I knew what I wanted so much. But as always in live, I had to negotiate obstacles: the lack of money and my parents.
But finally, I got my Commodore VC20 (<- sic, that's how we call it in germany). Many years later, after hours and hours of programming ML and experimenting with the electronics inside, some sort of magic smoke arise suddenly, and this was the final scene of my first Commodore.
Afterwards I had another VC20, this time I promised myself to be more careful. And this piece survived till know, buried and forgotten for a long time, hidden in a storage box waiting to see the light again.

After some care and soap the VC20 looks still very good and is working like a charm. And how old is it? Glad you asked, it's a newer CR-Model with the SER NO WGA 135xxx

... and I'm pretty sure You know how that story goes ;-)