Website of Jan Derogee

What is it:

A home computer of the 80's needed to store it's data somewhere and since disk storage was expensive, many starting users used audio cassettes. Although most systems allowed for the use of an ordinary shoe-box audio cassette recorder, this wasn't really a good sollution as there were many things that could go wrong. Sure if you knew what you were doping things were all fine, but most user didn't have a clue. Fortunately many brands of home computers offered a dedicated cassette recorder of some kind, a system in which all settings were fixed, so there were less variables to mess with. This improved the user experience greatly. The 1980's were also the point in time where double deck audio cassette systems started to emerge and it didn't take long before the general public used these Hifi-systems to copy audio tapes "mostly" for "personal use". Although these systems were also used for copying audio cassettes that were to be sold for profit. Computer users started to realize that this could also be done with game cassettes, so software piracy on a greater scale started to happen. Cheap copies with cheaply looking black and white labels (the color copier wasn't really invented yet) were sold for bargain prices. But... many of these copies were of dubious quality. And many of the copies some kids made at home on the big brothers Hifi-system were completely useless. The problem was that tapes copied on Hifi-systems suffered for signal degradation that caused the computer to misread some of the tapes under certain conditions or sometimes all of the tapes to be completely impossible to read at all.

What it does:

The 1560 is a device that consists of two 1530 datasettes, by combining two datasettes into one device making a tape copy is less complicated. Besides... it looks really cool and this is perhaps the only one of it's kind. Although I wouldn't be surprised if somebody else has already done this decades ago.

How it all started:

Unlike the scene in the video I wasn't hit with a datasette, but there was a moment in my life where the idea suddenly hit me. I thought it was cool, started to experiment and came to the conclusion it could be done. It took quite some time to get the project finished as I found all sorts of reasons to keep postponing the project. Then finally all things came together and I made the project video, which is the last piece of the project and a way to go through all the required steps of such a project, finding all sorts of flaws in the process and fixing them as I go. Then when the video is finished, the project is finished.

Why Hifi-stereo-systems aren't really suited for copying computer game tapes:

For those of you who wonder why dubbing tapes on your double-deck stereo cassette Hi-Fi audio system doesn't/didn't always work, the text below might shed some light onto the situation. To prevent confusion about the term double-deck, I mean a hifi stereo system that allowed two audio cassettes (in many cases labelled: tape-A and tape-B) to be used at the same time. One deck played the tape, while the other recorded. Some systems even had a special function, name high-speed dubbing, this allowed a tape to be played back a twice the speed, cutting the tape duplication time in halve. Below a short list of things that might/will cause problems when copying a cassette that holds a computer program or game:
Mono vs stereo:
Computer tapes are recorded as mono while Hifi-systems are stereo. Meaning that the computer tape uses one wide "mono" track where the Hifi-system uses two narrow "stereo" (Left and Right) tracks. Although the stereo track are located at the same location as an mono track and mono tracks (allowing for mono tapes to be played back in stereo systems). This means that both systems are interchangeable but this doesn't mean it's perfect. After all, a mono track is about 2.5 times the width of a single channel stereo track. And although the Left and Right signal are simply added by the mono-head, there still is an area on the tape that doesn't contain a signal. Meaning that the signal written by the stereo-head and read by the mono-head, will read a signal that is about 30% weaker than if that same signal was to be written by a mono-head. This doesn't sound like much, but things do add up, since this isn't the only problem you are about to encounter.
Now there is one other thing... assume you have an old tape, a that holds data (games/programs and perfectly recorded in the mono format) and you use that as the destination tape in your copy on your stereo Hifi-system. Then you overwrite the original data of that tape with new data... and depending on the erase-head used in your Hifi-system, the old recording might only be partially erased, because the stereo tape-head in your hifi machine doesn't record the area of the gap between L and R. Meaning that whatever signal was there is... never changed, so you would have a narrow strip of the old signal in between the two Left and Right tracks of the new signal. Fortunately... this was already solved by most tape-deck manufacturer. As there is an erase-head in your tape-deck that erase-head erases the entire width of the mono track (is essential is a mono erase-head, since that is cheaper). But the erase and read/write-heads are some space apart, so there will always be a small section of the tape that isn't erased when you start you recording. So this problem is mostly fictional.
Signal strength:
Saturation recording (or actually the lack of) is another issue. Cassette recorders used by home computers also referred to as datasettes, they store the information on the tape using a method called "saturation recording". This sounds fancy but simply said it just means that the information on the tape is stored as loud as possible. The tape is either fully positively or negatively magnetized. Which is perfectly fine for a digital signal. A Hifi-system cannot function this way, it would sound horrible, so audio recordings store the data in a magnetization level proportional to the strength of the audio signal. In fact most Hifi-systems will prevent the tape from being saturated, so the amplifiers will scale down the signal is it becomes to loud. This effectively means that when copying a digital computer tape on you audio Hifi-system, the saturated signal will be scaled down to more gently signals... reducing the signal strength on the tape even further. As the image below shows, there is less contrast in the signals of the tape written by the stereo-head of the Hifi-system. This means that the datasette will may have trouble in reading the signal properly.
Noise:
Knowing that track of a mono recording is 2.5 times the width of a single side of a stereo track it isn't hard to imagine that the signal to noise ratio of a mono signal is theoretically superior to that of a stereo signal. It requires some advanced signal theory/aleatoric calculus to explain how noise functions, but you can imagine that each ferric particle has a chance of "spoiling" whatever you record on it with a random amount of variation (let's call this noise), this chance is constant for a given formulation of tape. Using more grains equals more tape area to record the same information, this results in this overall "spoilage" being smaller. In layman terms, the narrower and slower you record, the effect of the noise becomes more significant, as there are less particles carrying information. The faster and wider you record increases the natural noise with particle quantity (however, you can only improve the SNR up to a certain theoretical maximum, dictated by the properties of the material). To improve SNR, you can go either faster, wider or both. To improve frequency response you need to go faster or use smaller particles for a given tape speed, as you need the media passing along the tape-head to change the magnetic flux more rapidly, in order to represent higher frequencies. Now normally, with saturated tape recording, noise isn't an issue, but since Hifi-systems do their absolute best to avoid saturation (to which we also may refer to as clipping) this might add to the list of potential problems.
Azimuth:
Then there is the well known problem of azimuth, how do you know if the tape-head in your Hifi system are perfectly aligned, in most cases they will be good enough, but that doesn't mean perfect. And how do you know, without special tools (a reference tape and an oscilloscope, which will show that a perfect azimuth will show the Left and Right signal to be in perfect phase) there is no way you can adjust the azimuth of your Hifi-system, where on the datasette there are plenty of free tools to help you with that. However, you cannot compensate for a bad recording, so a tape read and copied with the wrong azimuth is ruined for ever. Below an image of the azimuth problem, the signal on the tape is perpendicular to the direction of tape travel, so when the tape-head isn't perfectly aligned with the tape the signal will be read skewed or written skewed. Keep in mind that a tape written in a misaligned datasette will be read perfectly fine by that same datasette, but when that tape is played back in a datasette in which the head are aligned correctly problem will occur. The problem of a wrong azimuth is that the high frequency response will be reduced, causing in the "digital" signal of the tape to be read incorrectly. Recording level:
Audio level of the recording is also very important. Since the datasette expects a signal of a certain level, it must be as loud as possible, saturated to be more precise. Some Hifi-systems allow to set the recording level manually, other Hifi-systems simply don't and record the signal to the tape with some fancy "signal limiter" electronics, preventing distortion. If you have a Hifi-system that allows you to control the recording level, you can experiment with that setting and perhaps achieve some good results.
Tape speed:
Then there is tape speed... if your deck-A has a deviation of 3% (too slow) and your deck-B has a deviation of 3% (too fast), then your copy will be playing 6% too fast. Or the other way around, if your deck-A has a deviation of 3% (too fast) and your deck-B has a deviation of 3% (too slow), then your copy will be playing 6% too slow. If both decks are at exactly the same speed (because of proper calibration OR because the tape mechanisms use one motor for both decks) then both tape runs at the same speed and the absolute speed error doesn't matter. It is highly likely that your Hifi-system has a motor for each deck (since this is cheaper as it uses a more conventional mechanism), then this might get you into trouble when using the high-speed dubbing function. Because during high-speed dubbing both decks will have a new tape speed, they are intended to be twice as fast as normal, but how do you know if this is exactly X times for both decks?
High-speed dubbing:
The high-speed dubbing function may also affect the frequency response of the analog electronics inside your Hifi-system meaning that the playback and recording might not operate exactly in the same way as during normal playback/recording. Because at twice the speed, the electronics needs to be able to handle the signals at twice the bandwidth. And not all decks can do that, resulting is a loss of high frequencies, resulting in a bad copy.
All sorts of settings:
Then there are of course the settings on your Hi-Fi system, with settings like, Dolby A,B,C, tape type (although that should be automatic, due to the mechanical design of the tape that allows for tape type identification) 70us or 120us settings, lot's of things can go wrong and they mostly result in loss of high frequencies, which is a bad thing for digital signals.
Maintenance:
It goes without saying that your HiFi-system must be in top condition when you do this. Meaning that belts need to be in good condition and all speeds need to be correct, wow-and-flutter must be close to perfect and finally your tape-head(s) must be clean (properly aligned) and in some cases even demagnetized.
Conclusion:
If you encountered problems copying tapes recently or 40 years ago, then you might now no longer be wondering why some of your friends were able to make the perfect copies of tapes on their Hifi-system, while you never could. Life sometimes isn't fair, but making copies is a form of software piracy, so that isn't fair either. As a result your lack of knowledge (or available hardware) prevented you from going to the dark side of software piracy, consider yourself lucky.

Schematic:

Here is the schematic of the 1560 datasette. Basically the switch does all the work, it toggles the LED's to indicate which tape is the currently active one used for loading data into the computer. And in order to copy from one datasette to the other, the inverted signal of tape-A is used.
The 1530 datasette has a RED LED next to the tape counter, this LED has been replaced by a color LED that can be OFF, GREEN or RED. The LED is GREEN when the tape is used as the primary source for loading data into the computer. When the datasette is in recording mode it will turn RED. Please note that it is possible to record the data from the computer at the same time on both tape-A and tape-B. And that tape copies can only be made from A(source) to B(destination).
The switch can be set into A or B and allows for the following functions:
Switch set to A (LED tape-A=ON, tape-B=OFF)
tape-A: LOAD/SAVE data to/from computer, tape-B: copy data from A

Switch set to A (LED tape-A=OFF, LED tape-B=ON)
tape-A: SAVE data from computer, tape-B: LOAD/SAVE data into computer

Alternatives:

Although the 1560 datasette is a fun idea, an easier sollution is by using a simple splitter PCB, sometimes referred to as a tape duplicator or clonemaster. This almost does the same thing, it connects two datasettes to the same computer (which it really only requires for power) and it includes an inverter circuit to use the inverted signal of the primary datasette in order to write the data to the secondary datasette. There are websites who sell this at a reasonable price. Below some images if found online that show you these kind of devices along with a schematic which shows how simple they are. The integrated circuit 74LS04 does nothing more than to invert the signal from the "original" datasette and sends it to the "back-up" datasette.

1560 double decker