Lexicon

A

• ASCII: A Japanese company responsible for several standards, including the MSX. It is also behind the character encoding standard (the ASCII table).

B

• Bank (mapper): A chunk of memory (8 or 16 KB) managed by a register that allow to select what part of the mapped ROM (segment) is visible in the given bank. For 8 KB mappers, there is 2 banks per page and for 16 KB one, there is 1 bank per page1.

• BIOS: The core program found on all MSX computers that provides standard access to MSX peripherals (keyboard, display, sound, etc.). The BIOS may vary from one MSX to another, but all have a standard routine library that must function exactly the same way and be accessible at fixed addresses on page 0 (addresses 0x0000–0x3FFF).

C

• CPU: The central processor unit (CPU), is the processor that executes instructions of the program, such as arithmetic, logic, controlling, and input/output (I/O) operations. See Z80.

M

• Mapper: A device that contains one or more registers that allow to select the chunk of memory that is visible through the pages where the device is selected. These registers are generally accessible either via I/O ports, or via write access to given addresses.

• Mapped-RAM: A device with a mapper that allow to select chunk of the RAM (called 'segment') to be visible in each mapper's address blocs (called 'bank').

• Mapped-ROM: A device with a mapper that allow to select chunk of the ROM (called 'segment') to be visible in each mapper's address blocs (called 'bank').

• MegaROM: A ROM of 128 KB or more (1048576 bits, or 1 mega-bit, hence the name MegaROM). All MegaROM are Mapped-ROM.

• Memory space: The total memory address space visible by the Z80 (64 KB from 0x0000 to 0xFFFF).

P

• Page (memory): A quarter of the memory space (16 KB). The page number is defined by the 2 higher bits of the address. MSX allow to select an given slot/subslot to be visible in each page.

R

• R800: The secondary 16-bit CPU found in the MSX Turbo R and designed by ASCII. See also Z80.

• RAM: Volatile memory that allows variable data to be stored as long as the MSX is switched on. Programmes require varying amounts of memory and therefore only run on machines with sufficient memory. MSX1 models have a minimum of 8 KB of memory, MSX2 models have 64 KB, MSX2+ models have 128 KB and MSX turbo R models have 256 KB.

S

• Segment (mapper): A chunk of mapped ROM (8 or 16 KB) that can be selected into a given bank.

• PSG: The programmable sound generator (PSG) is the MSX audio standard. All MSX computers are therefore equipped with a compatible chip, usually an AY-3-8910. It allows the generation of square waves across three channels, the application of envelopes, and the generation of noise.

Z80

• Z80: The 8-bit CPU found in all MSX computers. See also R800.