A minor success story compared with some I read here, but I wanted to share it with you... This weekend I finally got my Tektronix 4052 graphics computer loading and saving on a Commodore 8050 disk drive. The problems: Commodore's weird handling of IEEE-488 protocol, especially with OPEN and CLOSE. This requires bit 7 (the 128s bit) to be set when sending a secondary address; bit 4 - usually the 16s bit of the address - tells the drive whether it's an open or a close. This was easily solved - the Tektronix WBYTE statement gives full control over such things. But the Tek is designed as a tape based machine. You FIND a file on the tape and type OLD to load it. The machine then resets and loads the program. On a disk, you WBYTE @40,240: some bytes to specify the file name. But if you type OLD @8,0: it asserts IFC during the reset, thus causing the drive to have forgotten all about your program by the time it comes to load it... So I toyed with the idea of cutting the IFC line in a suitable cable. But then I came across the APPEND statement. "APPEND @I/O address:line number" loads a program without resetting, renumbering it to start at the specified line. Neat. So I now have a program to display the directory of the disk, prompt you for a filename and APPEND the file on the end of itself. It then performs an INIT (initialise variables, IFC and things) and drops into the program. Saving is easier, so less automated. You type something like WBYTE @40,241:48,58,80,82,79,71,82,65,77,32,78,65,77,69,-13 WBYTE @63: SAVE @8,1 WBYTE @40,225,63: Not perfect, but it works. If anyone has an 8050 at the VCF, I'll happily demonstrate! Now, has anyone got a PET hard drive? And, for that matter, has anyone got a MUPET system for sale? Philip.