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The SAM Coupé (Pronounced: ''"Sam Koo-Pay"'' from its original British English branding) is an 8-bit British home computer that was first released in late 1989. It is commonly considered a clone of the Sinclair ZX Spectrum computer, since it features a compatible screen mode and emulated compatibility, and it was marketed as a logical upgrade from the Spectrum. It was originally manufactured by Miles Gordon Technology (MGT), based in Swansea in the United Kingdom. ==Hardware overview== The machine is based around a Z80B CPU clocked at 6 MHz and a 10,000-gate ASIC. The ASIC performs a similar role in the computer to the ULA in the ZX Spectrum. The Z80B CPU accesses selected parts of the large memory space in its 64 KB address space by slicing it into 16 KB banks and using I/O ports to select the particular blocks appearing in each 16 KB bank. The basic SAM Coupé model has 256 KB of RAM, upgradable internally to 512 KB and externally with an additional 4 MB (added in 1 MB packs). The computer has a direct connection for a cassette recorder for data storage but two 3.5 inch floppy disk drives can be installed within the case as well. Six channels of 8-octave stereo sound are provided by a Philips SAA1099 sound generator chip. The ASIC also includes a screen line interrupt, allowing video effects to be synchronised to specific display lines with little effort. The SAM Coupé provides four graphics modes: * ''Mode 4'' — 256×192, linear framebuffer, 4 bits per pixel (16 colours) = 24 KB * ''Mode 3'' — 512×192, linear framebuffer, 2 bits per pixel (4 colours) = 24 KB * ''Mode 2'' — 256×192, linear framebuffer, 1 bit per pixel with 32×192 separate attributes for each 8×1 block of pixels = 12 KB * ''Mode 1'' — 256×192, separate attributes, non-linear framebuffer arranged to match the display of the ZX Spectrum = 6.75 KB All modes are paletted, with a 16-entry CLUT selecting from a palette of 128 colours. Palette entries consist of 2 bits for each of the red, green and blue components as well as an extra bit which slightly increases the intensity of all three components. The machine's non-standard SCART connector includes signals to drive a TTL-style monitor, in which case the total palette of colours is reduced to 16. In order to match the display speed of the ZX Spectrum, the Coupé introduces extra wait states to reduce the CPU speed while in Display Mode 1. The Motorola MC1377P RGB to PAL/NTSC encoder creates a composite video signal from the machine's RGB- and Sync-signals (output by the ASIC) for the RF modulator. The machine shipped with 32 KB of ROM containing code to boot the machine and a BASIC interpreter (SAM BASIC) written by Andrew Wright and heavily influenced by his earlier Beta BASIC for the ZX Spectrum. No DOS was included in the ROMs, this was instead loaded from disk using the BOOT or BOOT 1 command, or the F9 key. The majority of disks shipped with SAMDOS, the system's first DOS, on them so that they could be directly booted. An improved replacement, MasterDOS, was also developed offering faster disk access, more files and support for the Real Time Clock for filestamps amongst many other improvements. The BASIC was very advanced and included code for sprite drawing and basic vector shapes such as lines and circles. The screen co-ordinate system for these was variable and could be arbitrarily scaled and centred. A provision for "recording" sequences of graphics commands so that they could later be repeated without the speed penalty of a BASIC interpreter in between, very similar to the display lists of OpenGL, was provided. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「SAM Coupé」の詳細全文を読む スポンサード リンク
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