Digital Signals FAQ Version: 5.3

Missing Content

A major pet peeve of mine is when something on the interweb disappears.  This is especially true when lots of other sites link to said content.  I was perusing the /r/RTLSDR wiki entry for Digital Modes and Signals Identification resources when I ran across a link for the Worldwide Utility News (WUN) Digital Signals FAQ. I was excited to read its contents when, low and behold, I got the dreaded 404 – Site Not Found error.

The WUN is Defunct

According to HFUnderground.com, (aka the HFU),

“The Worldwide Utility News or WUN club was an internet based radio listeners club for Utility Signals under 30 MHz, which operated for over a decade, from January 1995 to March 2006…”
“…WUN survived until March 2006, when it folded as many key columnists of the newsletter and support stuff (Day Watson, Jason Berri and Ary Boender) retired and could not be replaced. It was succeeded by the Utility DXers Forum (UDXF) which is involved mainly in the exchange of utility logs via a mailing list and does not publish a bulletin.”

A Saved Copy of the Digital Signals FAQ Version 5.3

I dug around for a while and finally found a copy of the Digital Signals FAQ on archive.org.  To save the next person the trouble of tracking it down, I saved a local copy here:

Digital Signals FAQ Version: 5.3

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Reverse Engineering the Final Cartridge III – Part 4

Final Cartridge III Working Screenshot 1 Success!  The final component arrived and the cartridge is working as expected!

One thing that I am still curious about though is that the date is listed as 1991.  The latest ROM image that I have found has been from 1988.  I’m not sure if the date was modified by someone along the way or if this is a much later revision of the Final Cartridge III ROM.

Final Cartridge III Working Screen Shot 2Final Cartridge III Working Screen Shot 2Final Cartridge III Working Screen Shot 4

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Reverse Engineering the Final Cartridge III – Part 3

Final Cartridge III PCB Back from FabThe printed circuit boards for the Final Cartridge III have come back from the fab.  Turnaround time was much better than expected and the quality of the boards overall is excellent.

I am still waiting on one part to arrive before I can complete a working prototype (the 74163 IC).

I programmed one of the 27C512 EPROMS that I ordered and quickly assembled a unit with the parts that I had on-hand.  Hopefully the 74163 will arrive this week so that I can test the unit.  I would also like to see if I can somehow get the board to fit into as Commodore cartridge housing.  I think that the electrolytic capacitors probably stand too tall to fit but I may be able to bend them out of the way and come up with a work-around.

Final Cartridge III Partially Assembled

Final Cartridge III Partially Assembled

You can see that IC2 (74163) is missing from the first-run prototype and how tall the electrolytic capacitors are.

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Reverse Engineering the Final Cartridge III – Part 2

Final Cartridge III PC Board Layout by e5frogI sent e5frog’s PCB layout for the updated Final Cartridge III to OSH Park and for $42.95 USD I was able to order three printed circuit boards.  I was rather surprised at how quickly the boards went to fab (same day) but at this point I don’t know just how long it will take for the completed boards to be shipped to me.  I ordered the necessary components from China hoping that everything might arrive in the next couple of weeks.

There are a few of the components specified in the BOM that are now considered obsolete and were slightly difficult to track down.  Fortunately, as they say, “eBay is your friend” and I managed to find all of the components.  Now the waiting game begins.

 

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Reverse Engineering the Final Cartridge III – Part 1

Final Cartridge III Schematic v1.3.1

The Final Cartridge III was an amazing piece of hardware when it was introduced in the late 80s.  It provided over 60 new functions to the C64-user including additional BASIC commands, an incredibly fast Fastloader, a Freezer, a Monitor and a snazzy graphical user interface with windows.  I had one way back then and I had been eyeing used ones on eBay for a while.

This project came to life from a discussion on Lemon64.  Hyvax had run across this website (in Czech) where the author (Ondřej) had reverse engineered the original Final Cartridge III and decided to make some improvements.  He built his own version of the original cartridge with support for a much larger ROM, the idea being that it could hold additional software.

e5frog joined the discussion and provided a link to a schematic of the original FC3 on Zimmers that was produced some time ago by an unknown author.  Hyvax began work on building the clone cartridge as it was laid out by Ondřej while e5frog recreated the board layout so that would fit inside a standard Commodore cartridge shell and used a more “sane” layout with fewer vias.  After some modifications, he released the schematic and board layout in EAGLE format.  Stay tuned…

Original Final Cartridge III

Original Final Cartridge III

Final Cartridge Advert Run Magazine (Nov 1987)

Final Cartridge Advert Run Magazine (Nov 1987)

Final Cartridge Advert

Final Cartridge Advert

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Adding a Parallel Connection to the 1541 Floppy Drive

1541 Parallel Connection

1541 Parallel Connection

The Commodore 1541 floppy disk drive communicates via a serial connection (the so called IEC bus).  Due to the way that this was implemented, the bus is very slow.  As another blog put it, “this bus…has wasted literally billions of hours of users.”

It is possible to attach a parallel interface to the 1541. This not only speeds up transmission time, it also makes it possible dump raw data from the drive as a continuous stream.  This allows some copy protected disks to be copied.  The ZoomFloppy supports a parallel connection as well – allowing rapid conversion of physical floppy disks to D64 images using OpenCBM.  (It is also possible to create D64 images of protected disks using another application – NibTools)

Adding a parallel connection to the 1541 is relatively easy.  Nearly all of the Commodore drives have their 6522 VIA socketed.  Peter Schepers has been making parallel cables since at least 2009 and I decided to purchase one of his pre-made cables rather than making my own.

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Commodore 64 & 64C Board Identification

Sometimes it’s helpful to recognize which Commodore 64 board you are working on.  The following information comes from the C64/C64C Service Manual published March, 1992.

C64 BOARD IDENTIFICATION

To date there are 4 versions of 64 PCB assemblies in use.

VERSION    IDENTIFYING FACTORS          PCB ASSY#       SCHEMATIC#
Original   5 pin board                  326298-01       326106
           (CN5-Video port has 5 pins)
A (CR)     8 pin board                  250407-01       251138
           (CN5-Video port has 8 pins)
B          8 pin board                  250425          251469
           (Reduced oscillator circuit)
B-2        8 pin board                  250441-01*      251469
           (Reduced Osc. w/component changes)

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JiffyDOS for the Commodore 1571

jiffyDOS Logo

Having recently installed JiffyDOS in the Commodore 128, it was time to move on to an actually floppy drive and install JiffyDOS for the Commodore 1571.  In all honesty, I mainly interact with an SD2IEC with D64 images (and at this point I have made D64 images of all of my floppies) but I do occasionally use an old floppy or two.  I ordered the 1571 JiffyDOS ROM from Jim Brain at Retro Innovations at the same time I ordered my Commodore 128 JiffyDOS ROM.

Installation is pretty straightforward – remove the bottom of the case, flip the case over, remove the top cover, remove the power supply, identify the stock 1571 ROM, replace it with JiffyDOS ROM and reverse steps to reassemble. Continue reading

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Atari CX40 Joystick Rebuild

Atari_CX40_Rebuild_001

Back in the 80s I used an old Atari 2600 joystick to play all of my games – both on the Atari 2600 and later on various Commodore computer systems.  I recently found one of these old Atari CX40 joysticks at a secondhand store for $2 and immediately purchased it.

Cosmetically the joystick was in pretty good shape.  Some of the paint was worn on top and the dust boot was dirty but intact.  The biggest problem with the joystick was that the contacts has become “dulled” and were not nearly as responsive as they should have been.

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Covox Voice Master

Covox Voice Master Disk Label

I have always been fascinated with the Covox Voice Master – an early voice digitizer that records and stores words and sounds for later playback.  An important feature of the Covox Voice Master is that pre-recorded speech and sounds can be played back without any additional hardware.  That is, you can create a program that features digitized speech using the Voice Master and someone without a Voice Master can run the program and hear the recorded sounds.

Back in the 80s I borrowed a Voice Master from my friend Matt for several weeks and created a few applications that used digitized speech.  When I ran across one on eBay for $13.27 I couldn’t resist picking it up for sheer nostalgia’s sake.

The device itself arrived in excellent condition and much to my surprise, the 5.25″ floppy disk was still readable.  (The cardboard box was in bad shape but I didn’t care about the packaging all that much anyway)  I immediately used my ZoomFloppy to make a D64 image of the Covox software to ensure that the software could be properly archived.  Over the years I’ve seen a few posts on various forums from people looking to obtain a copy of the software for use with their own Voice Master units.  I have made a copy of the D64 image available here (175k) should anyone need a copy.

Covox Voice Master Unit Covox Voice Master Manuals Covox Voice Master Box Covox Voice Master 5.25 Floppy Disk

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