1541 Floppy (Commodore 64)

an alternative to the cassette tape on the c64 is the 5¼" floppy disks the 1541 floppy drive for the commodore 64 connects to the c64 via the serial port there are most commonly 2 versions of drive they are both much larger than the cassette tape drive, with the first being the largest, then the 1541 ii (mark ii, second version) being smaller there as several versions some power on with just mains, and others use a custom adapter like the 1541 ii the power supply is specific to the 1541 and not the same as the c64 power the 5v rail is rated at 700ma and pulls 400ma the 12v rail is rated at 500ma and pulls 500ma, so really wants to be 1a connecting to c64 in order to connect up the floppy drive to the c64 you need a serial cable connect this between the floppy drive and the c64 head test a simple test if the head is good is to disconnect the wire that goes to the magnetic pickup head and test all the wires (usually 4) with continuity between themselves so put your meter into resistance mode, one probe on a wire, then touch over the other 3 wires one at a time as you do, you should see a reading around 4 to 20ohm typically open circuit or over 100 ohm is considered bad and basically not fixable rom eprom the floppy disk drive has a rom onboard that can be removed, read in using an eeprom reader, or replaced with a new one to check it is good the 1541 with board rev 154008, 154050, 250442, 250446 (old 1541 case) has the rom 901229 (dos hi rom) and can be replaced with 27c64 (8kb) the 1541 c with board rev short motherboard (sometimes old 1541 board in a new white case) has the rom 251968 (dos low rom & dos high rom) and can be replaced with 27c128 (16kb) the 1541 ii has rom 251968 (dos low rom & dos high rom) and can be replaced with 27c128 (16kb) if using an xgpro eeprom reader like the t56, select any ic with 2764 or 27128 depending on your version, and make sure to uncheck "pin detect" and "check id" then read, save to file and you can compare to known working dumps https //archbee doc uploads s3 amazonaws com/9enoacbhz7zqgrsars4gt/hobbfogblbtcf wdmnoy7 1541c251968 01 bin https //archbee doc uploads s3 amazonaws com/9enoacbhz7zqgrsars4gt/mywqbwhy250vftpj5vnvv 1541c251968 02 bin https //archbee doc uploads s3 amazonaws com/9enoacbhz7zqgrsars4gt/ 1ok3it0c446piveqryf9 1541 ii251968 03 bin via chips to test the via chips (mos 6522) it is best to remove them and put them in a backbit tester this way you can socket them and also be sure 100% of the functions are working cpu (6502) the cpu used is a mos 6502 to test the 6502 cpu it is best to remove them and put them in a backbit tester this way you can socket them and also be sure 100% of the functions are working alternatively probing the cpu for its !reset lines, address, data and other pins for confirmed operation is also an option gate array (251828) the gate array controls the motors for moving the head back and forth, as well as some other logic if you notice your head isn't moving or very little, it could be the gate array, it is fairly common to test the gate aray chip (mos 251828) it is best to remove it and put it in a backbit tester this way you can socket it and also be sure 100% of the functions are working list contents of floppy to list the contents of the floppy disk use load "$", 8 where "$" is a commodore shortcut for directory, as in load the directory contents, and 8 is the drive number (which is typically the first floppy drive (but if you have multiple it can be 9, 10 etc ) this will load the contents into memory, and now if you type list and press return it will display what was on the floppy disk load from floppy to load files from floppy, type load "filename", 8 replacing the filename for the correct one 8 if you are using a different drive number once it says ready type run to start most games will have files you need to find and run, so you can first run the load "$",8 then list to see the contents of the floppy and find the right file name to then call load "filename", 8 on