Skip to content

Archive

Category: Commodore

 
A couple of pictures of my Load-IT by Mills. I assume its a late model since everything is combined into the same PCB. Other Load-IT datasettes i own have a separate PCB for the meter.

 


 


 


 

 

I got a bunch of disks for transferring. As a routine I do an ocular inspection and make sure the disks rotate before starting the transfer. The only problem was that these disks failed on both parts.

The disks came from a storage unit that had a water leak and the disks were soaked with a mix of water and concrete dust.
 


Stains of concrete dust. Trying to rotate the disks by hand made a grinding noise. Nothing you’d put in a drive.


The disks were warped since the cushion inside the jacket had gotten wet. No wonder these disks didn’t rotate.
 
 


I needed a new disk jacket and to be able to clean up the disks before i could start reading the contents. The disk jacket I got from a donor disk. I used antimagnetic scissors to cut open the disk jackets, both the donor and the disks that I wanted to preserve. The magnetic disk can be moved slightly off-center to gain more space at the top so it won’t be damaged while cutting open the jacket.

When removing the disk, do not touch the magnetic surface. A good tip is to wash your hands with dish-washing liquid to remove grease from your fingers before starting. The disk can be slid out without needing to touch the magnetic surface. You can give the magnetic disk a push by the center hub ring or by the outer edge.

When the magnetic disk is out, use your thumb and pointer finger to hold the disk by the center hub ring and the outer edge. Alternatively put a couple of fingers through the center hub ring. Again, avoid touching the magnetic surface.

 

I had the disk under running water to rinse the dust off. With a few drops of dish-washing liquid on the fingers of my other hand, I carefully cleaned the surface. I started from the center hole and moved straight out to the outer edge.

 


Let the disk air dry. Dry wiping is likely to damage the surface. On some stains (or mold!) I used 90% isopropyl alcohol with clean cotton.

 


After the disk had dried, it was inserted into the donor jacket and I was able to get a good read of the disk.
 
 

Spectacular Copy Turbo to Disk, SCT2D, has become a widely used tool for preserving turbo tapes. It was originally part of the “Spectacular Copy” suite by Stephan Senz. “Turbo to disk” was extracted and has undergone many improvements on the way.

Latest addon to the tool is a Fast I/O save routine for 1541-family drives.

You can find the tool at CSDB, http://csdb.dk/release/?id=144377

 
SDT2D Changelog:

v1.2 by SAILOR of TRIAD
* Fastsave I/O for 1541 drives.

v1.1 by WACKEE of ARISE:
* Automatic replacing of invalid chars (,*?) before save [option].
* Accurate block size calculation.
* Proper handling of 0-byte files.
* Fixed resave on diskerror.
* Rename without space-fill.
* Tapeload with sound.
* Changed default settings.

v1.0 by SAILOR of TRIAD:
* Asks for disk change if file is larger than free blocks on disk.
* Resave option on diskerror.
* Option to rename file.
* Can use other devices than #8.
* Autotransfer mode option.
* Load error detection.

 

 


Xiny6581 has made a speed comparsion between SCT2D v1.1 and v1.2. Make sure to read his excellent tutorial on preserving tapes at http://sidpreservation.6581.org/how-to-preserve-tapes/.
 

 

d2d64_3

I needed a program to transfer C64 disks to .d64 images with a good overview of the process, but more importantly, it had to be fast and with minimial interaction to be used for reading disks in large batches. I ended up making a modified version of Nibread which i decided to call d2d64 so it would not be mixed up with the original Nibread. Nibread is part of the Nibtools utilities by Pete Rittwage at the C64 Preservation Project (http://c64preservation.com/).

d2d64 should not be used for preserving originals, it is only for making backups of your unprotected disks.

 
d2d64 has a new UI with a progressbar and colors to indicate status. It saves the disk as a .d64, defaults to 35 tracks, uses errorinfo if appliciable and will not reset/bump between reads. It also has an option for creating filenames based on the A/B-side of a disk. All you need to do is press Enter between the disksides.
 


I made a video on youtube that shows the process of transferring a disk. The whole video is 41 seconds, including initializing drive, turning disk and reading two disksides. Reading one diskside takes about 15-18 seconds. Hardware is a 1571 with serial cable (-s: SRQ) and a Zoomfloppy. OS is Windows 10.

 

There are two versions of d2d64 available. First one is based on nibtools (with SRQ support) for xum1541/Zoomfloppy users. This is probably the one you want. The second one is an older version based on mnib(predecessor to nibtools) and should be used with XMP/XAP1541 cables(LPT-connected drives). You can scroll down to the “Short history” part of this post for a brief explanation on the hardware differences. The older version I made between 2007-2010 when Zoomfloppy was not available. I decided to include it here in case some of you (like me) still have their XA/XM1541 systems running.
 

Download:


 

If you want to preserve your originals, visit these links below:
Kryoflux: http://www.kryoflux.com/
nibtools: http://c64preservation.com/nibtools

 

Short history
The Commodore drives communicate with serial communication through a DIN-6 plug cable between the drive and computer. For faster speeds, a parallel cable evolved allowing 8-bits to travel in parallel. The drive parallelcable was not a previous standard, but a cable soldered directly to the second VIA-chip on the drive and then connected to the C64 Userport.
 

The 15×1 drives don’t have a standard communication port and therefor you need a special cable to hook the drive to a PC. Early software even transferred files and images through the V.24/RS232-serial protocol.
 

Later on(1992-) came the X1541-cables which provided multiple options to connect your drive to the PC. The drive was connected to the PC through the LPT-parallelport which required exact timing to work. There were incompatibilities with some motherboards which were circumvented by different versions of the 1541-cable. The drive parallelcable was also available for the X1541 cables and added a “P” to the name.

Even later came OpenCBM, based on CBM4Linux, making it possible to communicate with drives under Windows NT/2K/XP with XA/XM1541 cables.

You can read everything about the X1541-cables at Joe Forsters homepage: here
 


My x1541 breakout box from the early days. This connected to the LPT-parallelport on a PC and disk transfering was done in DOS. Old PC-hardware did not work properly with all x1541-cables so i needed a device for testing combinations and different low level components.
 


XMP1541 in the making…
 

USB to the rescue
The LPT-Parallelport became more and more obsolete when the PC hardware evolved. Lots of tinkering with timings and settings was also required to get it working.
 
Till Harbaum worked on an USB adapter called xu1541 until he lost interest in 2007. Nate Lawson, with Wolfgang Moser and Spiro Trikaliotis, continued the project and developed it even further. In early 2009 the xum1541(pronounced “zoom”) was introduced, a full speed USB device with support for parallel transfers. Best known xum1541 implementation is the Zoomfloppy. Today OpenCBM also supports the xum1541.

 
Read more on the following links:
xum1541: http://www.root.org/~nate/c64/xum1541/
Zoomfloppy: http://www.go4retro.com/products/zoomfloppy/

 


 

A collection of disk covers that I have acquired during the years, also known as “Cover Art”. Use arrow keys or mouse scrollwheel to navigate though the covers and press enter or klick on the picture for a larger version.

Most of these covers are photocopies and some of them have had a rough life in the snailmail process. Addresses have been removed due to privacy reasons.

Thanks to Tech for a huge amount of covers.

 

2015-10: Added 183 covers.
2016-02: Added 3 covers by Microboy

 


 

 


 

    A friend of mine, Hedning/Genesis Project, sent me pictures of a 1541-clone that neither of us recognized and we asked around if anyone knew the name of the drive. Moloch contacted us with pictures and said it known in the US by the name “Commander II”. It might been stripped of the labels when imported to Euro-Land and sold as a different product. The Commander II was reviewed in Ahoy issue 16, 1985 (pages. 28-38).

     

    Update 2016-07-24: Hedning was generous and gave me one of his drives, thanks a lot! I added a few more pictures of the drive.

     
    Update: Thanks to Moloch we now have a name for this previously unknown clone. It was sold in the US by the name “Commander II”.

     


     

    The LEDs might been replaced with green/red since some traces were broken. I also removed a home-made deviceswitch due to its bad construction.

     

    The +5V is connected to the large area on this side of the PCB.

     

    The mech is a Chinon F-051.

     

     

    +5V/+12V PSU.

     


     

    Pictures by Hedning

     

     

     


    Serialports are located on the side of the drive.

     


    “Diskett” was a local Commodore computer shop/service center located in Malmö, southern sweden.
    The second drive, with serial 841633, does not have this sticker.

     

     

     

    1541clone_hp64_7

     


     

    Pictures by Moloch

     

     

     

     

FD-148 is a third party floppydrive for the Commodore 64.

 

 


 

 


Remove the screws marked with red and lift the cover.
 


You need to loosen 4 screws to remove the shielding and additional 3 screws to release the PCB.
 


Detach the white connectors and lift the main PCB. There is a ribbon cable beneath the PCB which also needs to be detached. The back plate can now be removed.
 


Remove the 3 screws marked in the picture. There are spacers below that PCB which you need to take care of.
 


Spacers marked with red.
Two voltage regulators(7805/7812) are fastened to the black heatsink to the right.

 


Flip the drive around and remove the 4 screws.
The drive mech is now loose, lift the plastic casing.
 


 


 


 


 

I have repaired a fair amount of drives, and every time I find myself loading a test or a diagnostic software from disk. This is a bit of a contradiction since the drive being tested, or repaired, might not even be able to load a program. I also have a variety of tools for different purposes and wanted to have everything in one place.

 

This is why i created a 1541 Diagnostic Cartridge.


 

The challenge was to get all these tools to fit into a 8K cart. I wanted to keep the hardware simple and a 16K cart would have overwritten the Basic interpreter.

Therefor I have optimized both code and visual on the tools to keep the size down. Some tools are old, others were written from scratch and a few I rewrote in machine code instead of basic. A couple of the tools are still in Basic, but optimized.

The cartridge is an 8K ROM at $8000-$9FFF

You can also use RESTORE to return to the menu.

You may need to send a “I0:” or turn the drive off/on before running further tests if an previous error has occurred.

 

 
Update 2017.09: The Cartridge is also available at the Protovision shop.
 
Update 2015.12: Upon request from their customers, The Shareware PLUS Commodore 64 & 128 Blog asked me if they could offer the 1541 diagnostic cartridge in their product sortiment. The 1541 Diagnostic Cartridge is now available in their eBay shop.

 

 

I had a broken 1571 on which I located the problem to the powersupply.

The PSU is relatively easy to refurbish with new caps and so forth, but I wanted to try out a switching powersupply i had.

The new powersupply is a MeanWell PT-65A and is rated 5VDC/7A and 12VDC/3,2A. It also has a -5VDC/0.7A output which was not used. This specific model was on a €4 sale at a electronics distributor and the current ratings were good, hence the selection.

 

WARNING! LETHAL VOLTAGES ARE PRESENT ON THE POWERSUPPLY.

 

 


1571 with original powersupply.

 

 


Mounting plate.

 


Testmount.

 


A very tight fit, I had to make a cut on the left side.
The PCB is mounted on spacers and the cables were crimped.

 

Finished assembly.

 

 

 

 

 

 

This post spawned out of a discussion at a facebook group about the commodore diagnostics reporting errors when using custom kernals. I decided to modify the kernal detection routine to identify good known kernals from a checksum table. Thanks to Jonny Hylander, Fredric QJ Blåholtz and Krister Andersson for ideas and suggestions.

586220+ : Initial version. Disassembly and kernel identification routines by www.worldofjani.com.

586220+ v0.4 : Marty/Radwar sent a huge list of kernal checksums. This version is able to identify a staggering 49 different kernals, for example Professional Dos, RapiDos, DolphinDos and Speeddos. Download the v0.4 sourcecode for a full list.

586220++ v0.5 SX-64 Tape Port check removal : KiWi at www.SX-64.de sent me a version which works correctly on the SX-64. Scroll down for the download and sourcecode. See his page here.

586220++ v0.5 Expanded window for paddle test by Sven Arke. Klick here.

586220* Proper chip number display for SX-64 and C-64 by Ted Saari. Readme.

 

Sourcecode for diag586220+ and original disassembly of the 586220 diagnostic. Compare these two files to see how the implementation was made.
Diag586220+ v0.4 by Marty / Radwar. It identifies 49 different kernals.
Standalone ROM Checksum program with diag586220+ v0.4 tables
Diag586220++ v0.5 by KiWi / www.SX-64.de
Diag586220++ v0.5 Paddle Update 08/2017
Diag586220* Proper chip number display for SX-64 and C-64 by Ted Saari 07/2018
Sourcecode for Diag586220*

 


 

Background.

The diagnostic 586220 does a checksum on the kernal ROM to verify if it is ok. It will only identify the original CBM ROMs. All other (even good, for example JiffyDos) kernals will be marked as “BAD”.

The 586220 was used since i have done an reassembly/disassembly of it earlier.

Code to calculate the checksum.

Depending on $FF80(Kernel revision) the checksum is either $E0 or $E1. This determines if Kernal is marked as “OK” or “BAD” by the diagnostic test.

I remembered that the C128 diagnostic cart displays the checksum. When running the C128 diagnostic(789010) the checksum on the C64 Kernal is reported as $D4. After investigating the code, which is identical to the one above except for the fact that only $1F00 of memory is checked. This is probably a mistake since the kernal is 8K ($2000 bytes).

We shared ideas about how this would be accomplished, but also noticed that some of the different kernals generated the same checksum. This might be deliberate for them to pass a diagnostic test.

 

All code below is compatible with 64tass (i.e. Turbo Assembler compatible).

The new checksum routine. To make a distinction, the address lowbyte is xor:ed and therefor not resulting in an identical checksum.

 

 

…I made a program that can identify the kernal ROM.

 

A table is used for the checksum and a pointer(.word) to the matching ROM name. You can easily add new checksums and ROMs to the code.

 

 


 

Incorporate the checksum with Diagnostic 586220
 
The goal is to replace the original checksum routine with the code above.

As we can see in the disassembly, the routine for ROM tests are at $890E. Further investigations reveal that code between $890E and $8A44 can be replaced. This area also has the routines to check BASIC and CHARACTER ROM.

 

Checksum routine is located a few lines below $8926.

After inserting the code, you can now assemble(compile) the code with c64tass. I won’t go into details about the code itself, but it is presented and downloadable further down on the page.

 

The output file (.o64) can now be written to an eprom. Skip the two first bytes (0x00, 0x80) which is the loadingadress of the file.
 

You can also test the cart in vice by converting it to a crt. Cartconv.exe is included with the Vice emulator.

 

586220-
586220+ diagnostic, it is now possible to identify the kernal ROM.

 

The new checksum code.

Checksums for BASIC and CHAR are also displayed.