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Commodore 64: Datasette Maintenance

So, Double Dragon had issues loading on a Tape Drive I'd acquired. It had come in a mouldy box, so I had a hunch that the drive itself would need a thorough clean and alignment.

There are multiple alignment tools, downloadable as disk images or PRG files. I could copy these onto my SD2IEC, but there was an issue: the SD2IEC gained power from the Datasette port which was now in use by the Datasette drive itself!

Powering the SD2IEC from the Datasette Cable

Fortunately, the Datasette plug has a screw that makes accessing the internal pins very easy. I opened it up, taking note of the cracked, flimsy plastic, and inspected the contents.

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The green wire, pin 2, is the +5v that we're after. Bare back some plastic on the wire so we can solder to it. I found a male+female standard round DC power socket to use. Make sure the female is on the 'power' side, otherwise you'll have a potential for shorts if there is exposed bare metal with current flowing through it. Of course, the outer metal is ground, but still better to be safer than sorry.

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From here I soldered on the plug and grinded out some plastic from where the main cable feeds in. This allowed the plug to hang out the end. Not the cleanest job, but it worked quite well. I sorted wanted to feed it out the side where the ground wire is... but I hadn't left enough length.

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Next, on the SD2IEC end, bare some wire also. Grab the plug and solder it on, then use some form of insulator to tidy it all up. Nothing a little duct-tape can't fix.

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Everything was plugged in and good to go!

Cleaning the head

Everyone recommends alcohol (isopropyl) wipes for this. The wipes have the benefit of leaving little residue and drying cleanly. You'll find that KFC wipes are also usable.


Take the swab out of the packet and wipe the heads, specifically the central metal one. I didn't actually know which way to wipe, or how much pressure to apply. So just be gentle and attempt to remove any visible dirt. Don't put a tape back in until everything is try.

Aliging the head

There are a few options here. Download Cassette Azimuth, also known as 'Recorder Justage', and Minimal Head Align. Both do the same thing, the former is more complex.

I copied them both onto the SD2IEC and then loaded them via the file browser. Cassette Azimuth is easy to work with. Load it up and then hit play on your tape. If nothing is happening then you'll need to start adjusting the player already. If you see data, and it's erratic, then you'll also need to adjust. The goal is to have straight vertical lines.

To actually do the adjusting, there is a tiny screw-hole above the rewind button that a small jeweller's screw driver will fit through. When the tape drive is playing, the hole lines up with the head adjustment screw. Turn this screw all the way clockwise (not too much pressure!) and then turn back in small increments as required. Pause between turns to let the screen update with the new readings.

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You can hit F1 to get the guide-lines for the data. I couldn't work out if the data lines were meant to draw over the top, or in between, or where... but at least I got them vertical!

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Here's the same process with Minimal Head Align. The app is much more raw; it starts off with a screen full of garbage which starts refreshing once you start feeding it data from the tape drive.

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Back to Double Dragon

I had assumed that all the loading issues were from a dirty/misaligned head... so I thought I'd try the game again now that the tape was producing cleaner, more vertical lines on the test programs. I didn't have much faith... but it worked! It took just as long as last time, but this time I got to the first level!

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The graphics are intense... hah. Controlling the character was hard at the start... then I realised it was because my controller probably hadn't been used in a decade. I'd found a sega mastersystem controller at a second-hand shop over the weekend. Works perfectly.

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So as the game was loading, it got to the point right before the title and asked me to reset the counter to 0. Turns out this is so that, when you die, you know where to rewind the tape to.

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From there you rewind to zero, press play... wait for the load and then have another go. I might try source the game on floppies to see if the extra data capacity allowed for a different version. Hmm... then again if this review is anything to go by, then there's no hope.


Commodore 64C: An Introduction

I've had a hankering for an Amiga for a while now... I don't know why.. I think it has something to do with the accelerator that was made for the Amiga 600 that made it go faster than ever thought possible... sure they emulate the entire core in a much faster CPU and high-jack the motherboard... but it's still an awesome feat!

I also have a feeling that I missed out on a whole realm of computing in my childhood by following the Nintendo/IBM route. I'm pretty sure there was a-whole-nother world out there... Sega, Amiga, Atari, TI, etc... that I never got to sample. Actually, I lie... my neighbour had a TI-99/4A, followed by a Sega Master System... but I only ever got to play them briefly. Hunt the Wumpus was random, but fun at the time!

My first Commodore

Officially, this is my second. The first was purchased in the mid-90s at a fair at high school, but didn't work. It was the original breadbox style and was stone dead. Should've left it in the garage!

Anyway, this past weekend I spied a box of junk at the local Trash and Treasure and actually thought I saw an Amiga 500/1200. Instead it turned out to be the 'newer' C64. I was hooked.

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The guy wanted $100 for the box. It contained:

  • C64C (missing 3 keys) + Power Supply
  • Composite Video Cable with Stereo Audio
  • Two quickshot joysticks
  • One control pad (looks like a NES clone)
  • 3 odd cartridges
  • Another odd console named 'Tempest'
  • 1571 External Floppy Drive

Now that I list it, it could well be worth the AUD$100. I offered $50. He haggled back to $60... knew I had him. Asked if it worked... he had no idea... so I pulled change from my pocket and made a deal at AUD$52.


Does it work?

Worked first time... plugged it in and switched to A/V input... blue screen of dea... BASIC!

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Random 4s and 8s on the screen... and the cursor was stuck hard-left. This directly mapped to the keys that were missing. 4, 8 and HOME. Turns out that there is no spring when the keys are off, so these were all 'pressed'.

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Got some tape, placed along the shaft of the missing keys to hold them in the air. Restarted... it works! Quick search on eBay on my phone, from the couch, in front of the LCD TV that was happily displaying technology from 1987. Found replacement keys... ordered them on the spot.

Next google to a sample BASIC app... found a tone generator. Tedious data-entry thanks to taped-keys... but it worked beautifully through the surround system. Hah.

How much more powerful is my phone than this? No idea.

1541-II Floppy Disk Drive

This is external and has its own brick of a power supply. Turns on and hums away when I attempt to access a disk... so I assume it's in working order. There's disks on their way via eBay, so I'll test it out shortly.

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The innards

See below for the case opened. I was curious as to why it had a green LED. Turns out Commodore could never work out what colour the LED should be. The warranty seal was also very well voided. Seems to be some newish solder around the PAL/NTSC circuitry... maybe this was a conversion?!

Turns out I have an Assy 250469 Rev. B. Built in 1990 (assumed by the scratched out '91' on the RF Modulator.) This model was still being built in the '92, so I seem to have acquired one of the final models.

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What's next?

  1. Yes, that's a model railway under the C64C... I will control it. Turns out I bought a book when I was young that was all about robots and the Commodore 64. I need a VIC-REL or equivalent. Bugger that... let's find the header for the user port and make my own!
  2. Buy floppies (thanks eBay) and test out the drive.
  3. Buy some form of flash disk and play all the games I missed out on. I chose the SD2IEC... waiting for it to arrive.
  4. Serial port? Modem? Ethernet?
  5. What else?

This is fun!