MSX extensions (2): cartridge board

EE February 1986 EXTENSIONS 2 Second in the series on home-made MSX add-on units, this article presents a cartridge extension board and full details on EPROM-stored programs The MSX cartridge As shown above, the present car- tridge extension board is the sort of design that many users would un- doubtedly like to see: universal, ac- cessible for measurements and experiments and with the possibility to insert one"s own EPROMs. How- ever, before this can all come true, some knowledge is required of the `cartridge conventions" used in MSX BASIC. We shall, therefore, first examine a typical MSX start-up pro- cedure. After power-on, MSX BASIC always establishes the amount of RAM (Ran- dom Access Memory) between ad- dresses 8000 and FFFF, and activates the largest continuous area en- countered. Next, BASIC examines slot address range 4000. . . BFFF. Each slot occupies 16 Kbytes, div- ided in four pages. At the beginning of every page, a sequence of codes is read to identify the slot cont...