DC2N by Luigi Di Fraia DC2N - a tape preservation device for Commodore and Sinclair homecomputers


Description Media files Ordering PC Software Technical
DC2N navigation pane by Luigi Di Fraia
This page has last been updated on: 1 Feb 2014.


Q. Which kind of files are supported for playback purposes? Does DC2N support turbo tape loaders (e.g. Turbo Tape 64, Novaload, Cyberload)?

A. Simply put, DC2N supports all turbo tape loaders and multiload programs/games: Whatever can be encoded within a TAP file (either version 0 or 1) can also be played back by DC2N.



Q. Can I dump C16/+4 tapes with DC2N provided that I use a 1530 attached to DC2N to read them in?

A. Yes, of course you can! DC2N can also record 0 and 1 states independently, which is a requirement for certain turbo loaders released for this computer.



Q. Can I dump Spectrum tapes with DC2N provided that I use a 1530 attached to DC2N to read them in?

A. Yes, of course you can! Massi cadenti has outlined a procedure for doing just that.
  • Optionally fine tune the datassette head in order to read most Spectrum tapes without alignment issues (using the Spectrum Test Tape).
  • Dump the tape with DC2N.
  • Convert the resulting TAP to WAV using Attila's excellent TAP2WAV or my own TAPWav, and
  • Run it through MakeTZX
Here you go, you can get excellent results without going through audio sampling.



Q. How do I connect the DC2N, power it, etc?.

A. If used as a datassette replacement for a Commodore computer, remove anything attached to DC2N (power supply, 1530) and connect it to the Commodore computer while the latter is turned OFF.

If used to dump tapes, remove the DC2N from the Commodore computer while the latter is powered OFF. Connect a 1530 (or equivalent tape drive) to the dumping port of DC2N and finally connect the power supply.



Q. Which kind of external power supply do I need to use with DC2N to dump tapes?

A. Please refer to the technical information section here.



Q. What SD Card manufacturer/size should be used with DC2N?

A. Size should not be a concern, but it has to be greater than or equal to 64 MB. The card needs to be formatted using FAT-16. DC2N supports partitions, so that users can make partitions on their SD cards. DC2N only supports MS-DOS filenames (8.3) for the time being.

The SD Card manufacturer IS relevant. DC2N is a hard real-time system that requires a fast write access to the SD Card memory. Certain low-speed/cheap cards cannot guarantee high speed during write access to any region of the card.

SanDisk's Extreme III (Class 6) 2GB SD Cards were tested successfully and are the ones recommended to be used with DC2N.

SDHC cards are currently supported but not yet benchmarked. Be sure to buy a reliable SD Card when you place a pre-order: getting SD Cards is becoming harder and harder.



Q. How do I format an SD Card using FAT-16?

A. It is very likely that if you ask the question, you are using Windows. In that case, use a card reader and right click on the removable drive that corresponds to such reader.
Select the options as per image below (Windows XP):

Windows XP - Format using FAT-16



Q. Can I use partitions on the SD Card?

A. Yes. The way this is done depends on the version of the firmware in use.

Firmware revisions prior to 1.67: Upon powering up the DC2N users are asked to select the partition to work with.

Firmware revisions 1.67 and later: In order to improve user experience and speed up interaction, these revisions will automatically mount partition 0 if it uses FAT-16, but will fall back to the partition selection choice if it's not.
Therefore, users on revision 1.67 and later have to format partition 0 using an unsupported file system, such as FAT-32, in order to be able to use partitions 1, 2, and 3.



Q. I can write data at up to 7MB/s to my SD Card, however that is not fast enough for DC2N and I get an "SD Card error" message, why is that?

A. Writing data to an SD Card is a two step process: send the data and wait for the card to write it to its flash memory. In a hard real-time system we have a strict requirement on the maximum time it takes for the two to occur, before we can carry out the next write access. Therefore the faster data is sent to the card, the more time we can wait for it to be written to the flash memory.

Benchmark testing on a PC doesn't matter at all because data is sent to the card way faster than DC2N can possibly do. DC2N uses SD Cards in SPI mode and the SPI clock frequency is just 4MHz (I actually extended it to 8MHz for beta testing only). This means that the write access to flash sectors must be quite fast because DC2N cannot wait for the SD Card to finish writing if it needs to write the internal buffer to the SD Card again.

A workaround has been tested successfully with different SD Card brands: If you run into the speed problem, just copy a big file (5-10 MBs) to the SD Card before attempting to dump again. Somehow the initial sectors of SD Cards seem to be slower and therefore by saving a big file to the card you get these sectors out of the way.

Even with this limitation on which SD Card to use with DC2N, SLC has made over 4000 dumps of his tapes. If anybody thinks this would be a problem for them, I discourage them from getting a DC2N.



Q. What's the best way to dump tapes?

A. For optimal SD Card usage I'd recommend users keep making dumps of their tapes until the SD Card is almost full. At that point it is also easier to fast format the SD Card, in order to carry on dumping.
It is advised that backups are made regularly while dump files are being added to the SD Card by DC2N.



Q. I dumped my tapes and converted the DMP files to TAP format, shall I keep the DMP files?

A. Absolutely yes! DMP files are valuable and should be kept by all means. Users might save them to a DVD if running out of disk space.



Q. Can I see what is going on while I am dumping, e.g. if the tape drive head is properly aligned to read the whole tape?

A. Yes. DC2N offers a data monitoring feature that is similiar to the one found in recorder-justage (aka head tester). While dumping a tape, the pulse distribution is shown on a terminal connected to the serial port of the DC2N, as per below:

DC2N firmware - Data monitoring by Luigi Di Fraia

If data clusters in thin bands, as in the above image, the dumping process is proceeding well.

DC2N firmware - Data monitoring by Luigi Di Fraia

If data is scattered all over the place, as in the above image, the tape drive head is not properly aligned to read the tape contents and it is not worth carrying on dumping it.

For details about the serial terminal program configuration, refer to the technical information section here.



Q. Can I use the data monitoring feature to realign the tape drive head for optimal dumping results?

A. Yes. Also, one DC2N user reported better results when using the data monitoring feature in DC2N rather than recorder-justage.



Q. Are there tools to check the quality of my dumps?

A. Yes, there are a few tools you might get used to if you want to check the data integrity of your dumps.

  • If you have little experience with tape images and just want to have an overall analysis of your dumps I would recomment tapclean. Binaries can be found in my C64 section.

  • If you have some experience with tape images, you might start from TAP Studio. The full set of programs for the TAP Studio group can be found in my C64 section here and here.

    If there are no pulses on their own in the middle of a stream, you can be fairly confident that the dump you are looking at is good. If you can see scattered pulses every now and then or all over the place, the dump you are looking at is probably unreadable and there is no point running it through tapclean.

    TAPStudio software by Luigi Di Fraia

    In the above image there are 2 spurious pulses, enough to make the game not load, easy to fix though.

    TAPStudio software by Luigi Di Fraia

    The above shows an unreadable tape image. Data is scattered all over the place. This tape image is unusable. Users having this result for certain tapes might try to adjust the tape drive head alignment.



  • Q. I am willing to dump my whole collection of originals, will you help me to check the dumps?

    A. I can definitely help you get started but I cannot check all of the dumps all of the DC2N users make. It is simply impossible for me to do so during my little time off the job. You'll have to get some degree of confidence and use the tools that I provide for that purpose. I am more than happy to make a comprehensive documentation for those tools based on users' feedback, however users have to do their bit: try the software and ask questions.

    Update: there's a certain amount of time wasters around who don't understand the difference between preservation efforts and the tweaks "somebody on some forum" has done for personal glory.
    Alright, so if you want to engage me you've gotta pay a £30/hour fee for restoration purposes, regardless of the outcome: let's see if there's anybody feeling like wasting my time when they have to pay for it.



    Q. I support retro-projects but your prices are too high. Why are they so high?

    A. Short answer: The DC2N is a fair-tade product.

    Long answer: The whole manufacturing process took place in a small factory in UK in the region where I live. The electronic components were bought in UK as well. The production of DC2N occurs in batches of just 25 devices. For all of the above reasons DC2N has such a high cost already without a case.
    Carving a case is a time-consuming process that requires the main part of my free time. If you think you have the skills and can spare the time to do it, please buy a kit version and save money.
    If you think that the DC2N manufacturing costs can be reduced for the next batch, I will be more than happy to read from you how to achieve that. However, I will not comment further on the prices I apply.



    Q. When I save a file from the C64 why doesn't the filename on the SD card match the one I gave to the file?

    A. The filename you specify when saving from a Commodore computer with e.g.
      SAVE "MYPROGRAM"
    is not used as dump file name by the DC2N. I'll make an example to illustrate how complex this is.

    Let's think about a digital camera: it saves pictures as DSCF0001.JPG and so on, or some sort of incremental count inside the filename. When you take a picture of a tree, say in Windsor Castle, would the camera be able to name the picture "Tree in Windsor Castle.JPG"?
    That's the very same concept here. The filename given to a program is preserved inside the DMP file (and then the TAP file when converted by means of dc2nconv), but there's no point for DC2N to dig into what is being saved and extract the filename.

    That's why files recorded from a Commodore computer (as well as tape dumps) will be named DUMP0000.DMP, DUMP0001.DMP and so on.



    Q. I am a Linux user, do your tools work under Linux?

    A. Yes, binaries of my tools are available for Linux as well. Firmware upgrade has been tested under Linux too. Please check the software index here.



    Q. What does the DC2N DMP format look like?

    A. Please refer to the technical information section here.



    Q. I'd like to playback a PRG file, is that supported by DC2N?

    A. No. I am not interested in supporting formats that are not tape images. If users want to be able to use their PRG files, then I suggest they save them to a TAP file.
    One way to achieve that is via the libtap library, available here. It includes a few tools that let users save PRG files to TAP files using different loaders. Binaries are available for both Windows and Linux, along with the source code.


    Comers since area creation: Since April 2002 - Best viewed at 1024x768



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