Just ran across the thread looking for info on the Sanyo MBC 550/555. I have a complete system that started out as the original 550 (had one 360 drive). I upgraded it to the 555 by adding the second drive, then upgraded to the double sided 800k drives. Installed more memory by piggy backing the memory chips and modifiying the power supply current limit sensor, added the PC video display card to make it more compatible with IBM type programs. Total of 512k memory. It came with MSDos 2.11 for Sanyo, Wordstar, Calcstar, DataStar, Pcwrite. It will run lotus 123 vs1.1. I have upgraded the Wordstar to the Pro version. I also have a multitude of "freeware" software that will run on it. I also subscribed to the Magazine that supported the unit and I have all of the copies that were issued relating to the 555. I used the monochrome monitor at first but shifted to using a Panasonic color monitor that had a pc input and ntsc input so I could use an external tuner and listen to tv while doing computer stuff and switch to the video if something sounded interesting. I also have the schematic diagram for the system. I used a Star Micronics dot matrix printer at the time. Fun time and learning experience. Donald E. Hogg Associate Director/Engineering Educational Communications Center Kansas State University 128 Bob Dole Hall Manhattan, Kansas 66506-6902 Voice==785.532.3141 Fax==785.532.7355 Email: dehogg(a)k-state.edu