Hardware Enterprise (computer)

1 hardware

1.1 cpu, memory , asic chips
1.2 keyboard , case
1.3 graphics
1.4 sound
1.5 interfaces

hardware

enterprise 128 rear view



enterprise 128 right view


cpu, memory , asic chips

the enterprise has 4 megahertz (mhz) z80 central processing unit (cpu), 64 kb or 128 kb of ram, , 32 kb of internal read-only memory (rom) contains exos operating system , screen editor / word processor. basic programming language supplied on 16 kb rom module.

two application-specific integrated circuit (asic) chips take of workload off of central processor. named nick , dave after designers, nick toop, had worked on acorn atom, , dave woodfield. nick manages graphics, while dave handles sound , memory paging (bank switching).

a bank switching scheme allows memory expanded maximum of 4 megabytes (mb). highest 2 address lines z80 used select 1 of 4 8-bit page registers in dave chip. output selected register used highest 8 bits of 22-bit address bus, while lowest 14 bits come directly z80 address bus. effectively, 64 kb address space of z80 processor divided 4 16k sections. 16k page 4 mb address space can mapped of these sections. lowest 2 pages (pages 0 , 1) of 4 mb address space contain system rom. next 4 pages (2 5) reserved rom cartridge (max 64 kb). top 4 pages (pages 252 255, totaling 64 kb) used video ram, can used storage of program code , data well. on 128k model, additional 64 kb of ram mapped on pages 248 251. remaining memory space can used external devices , memory modules connected expansion bus.

keyboard , case

the case unusual in contains both full-sized keyboard programmable function keys, , joystick. distinctive shape due designers desire break away customary designs. low-profile keyboard constructed mechanical keycaps on top of rubber membrane , has standard layout, feel of keys disliked many, or people, because keys weren t full travel , had squishy feel, similar sinclair ql or spectrum+. joystick replaces normal cursor keys, , allows cursor moved diagonally. royal college of art graduates geoff hollington , nick oakley responsible design.

graphics

enterprise has 5 graphics modes: 40- , 80-column text modes, lo-res , hi-res bit mapped graphics, , attribute graphics. bit mapped graphics modes allow selection between displays of 2, 4,16 or 256 colours, horizontal resolution decreases colour depth increases. interlaced , non-interlaced modes available. maximum resolution 640×512 pixels interlaced, or 640×256 pixels non-interlaced. these resolutions permit 2-colour display. 256-colour display has maximum resolution of 80×256. attribute graphics mode provides 320×256 pixel resolution 16 colours, selectable palette of 256.

multiple pages can displayed simultaneously on screen, if graphics modes different. each page has own palette, allows more colours displayed onscreen simultaneously. page height can larger screen or window displayed on. each page connected channel of exos operating system, possible write on hidden page.

sound

the sound handled second asic chip, dave , , has 3 sound channels plus noise channel. each channel s sound can placed freely in stereo image. available effects include distortion, low-pass , high-pass filters, , ring modulation. chip has programmable envelope generators more flexible synthesizers traditional adsr envelope, , allow 255 phases specified each envelope. on each phase, envelope can adjust sound s pitch , stereo balance.

interfaces

the enterprise came included array of connectors far beyond common on home computers of time. there rgb output, rs232 / rs423 serial port, centronics printer port, 2 external joystick ports, 2 cassette interfaces, rom cartridge slot, , ordinary expansion port. save expense, many of connectors did not use sockets, instead had simple edge connectors used exposed traces @ edge of printed circuit board.

the basic rom can replaced rom emulates zx spectrum, theoretically allows enterprise run catalogue of thousands of spectrum games. external floppy drive became available later, , allowed access cp/m programs, while @ same time being compatible ms-dos disc format , file structure (sub-directories etc.).