Floppy disc interface for the Junior - and other 6502 computers, Part II the Junior collects its stars and stripes

12-48 — elektor december 1982 floppy-disk interface for the Junior G. de Cuyper floppy-disk interface . . . and other 6502 computers, Part II the Junior collects its stars and stripes The second and last of these two articles describes the modifications that must be made to the hardware of the Junior Computer, to be able to run Ohio Scientific software on the Junior or any other 6502 computer. A new EPROM is required, to load software from the diskette during initialization (reset) of the computer. Documentation is available showing the source listing for the monitor program in the EPROM. Let us take another look in the circuit diagram of the Junior interface p.c.b. (figure 1). NOR gate N33 is replaced by a NAND gate. Line 8K0 or EX is now no longer active in address range $0000 1FFF. The new address range with the NAND gate is E000 FFFF. This addressing affects the memory chips of the Junior Computer as follows: — 48 K bytes of dynamic RAM are located in adress range $0000 BF...