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The MSX ("Machines with Software eXchangeability") specification was conceived by a group of companies led by Microsoft that saw the need for a common standard architecture in the home computer industry.
Many leading companies were involved, including Goldstar, Philips, and Spectravideo. The MSX logo was used to identify compatibility with the MSX standard between manufacturers of MSX equipment. The MSX specification, announced in 1983, enforced compliant manufacturers to build their machines to specific standards, both in hardware and software, such that programs on one MSX would also work on another.
All computers had the following common hardware:
- Zilog Z80A microprocessor running at 3.6 MHz
- Between 16K and 64K of RAM
- 32K of ROM to hold the Microsoft Extended BASIC interpreter.
- Texas Instruments TMS9918 graphics chip with 16K of dedicated VRAM (video RAM)
- General Instrument AY-3-8910 sound chip
- Intel 8255 Programmable Peripheral Interface chip (used for parallel I/O such as the keyboard)
- Four large cursor keys
- Ten function keys with some mapped to BASIC keywords.
Many of the above chips were integrated into single-chip designs by MSX manufacturers - these were called MSX-Engine chips. Before Nintendo released their Famicom console, many Japanese games studios focussed their attentions on the MSX. MSX computers all had the capability of adding a disk drive controller to any of the cartridge ports to allow the loading of games from floppy disk. The TMS9918 graphics chip supported 16-colour graphics at a resolution of 256 x 192, although each byte's worth of 8 pixels could only support 2 colours. It also supported 40x24, 32x24 text modes and a very low graphics resolution option of 64x48. It also supported up to 32 programmable sprites. Another standard was the Atari-style joystick port and the use of a cassette interface as the primary means of loading and saving data.
In May 1984, all member manufacturers had a deadline to release their MSX-compatible computers, and the first six were first displayed at the Japan Data Show in 1983. The following table lists some of the more common "MSX1" machines as they became known, and their specifications:
|Sony Hit-Bit HB-75||£299||64K||48K||2||Personal Data Bank software built into ROM with Agenda, Memo, Address Manager, and a Transfer utility.|
|Mitsubishi ML-F 80||£299||64K||32K||1|
|Yamaha CX-5 / CX-5M||£600||32K||32K||1||MIDI sound, 8 channels|
|Sanyo MPC 100||£299||64K||32K||1||Lightpen interface|
|Sega Yeno DPH-64||?||64K||32K||1|
|Pioneer PX-7||Can control Laserdisc players and VCRs|
|Spectravideo SV318||£199||32K||32K||1||Built-in joystick. Machine not 100% MSX compatible.|
|Spectravideo SV328||£275||80K||48K||1||Separate numeric keypad. Machine not 100% MSX compatible.|
|Spectravideo SV728||100% MSX compatible. Released in Autumn 1984.|
|Goldstar MSX||Imported to the UK by Micro Dealer.|
The MSX was popular in some areas of the world but in two of the largest, it arrived too late. The USA was in the middle of home computer price war between Commodore, Atari and others, and in the UK the Sinclair ZX Spectrum and Commodore 64 had already beaten almost all rivals out of the industry with market dominance.
Due to difficulties in porting existing games to work with the MSX, and a tendency for MSX video to be rather slow, it met with little success in these two major sectors. However, in Japan, South Korea, Spain, the Netherlands and South America, the MSX sold in great numbers.
Following on from the first specification, simply called "MSX", a further three generations of the standard were released:
MSX2, released in 1985, built on the MSX standard with the following enhancements:
- 48K ROM
- Extended BIOS
- MSX BASIC v2.0 or v2.1
- Disk ROM
- MSX Audio BIOS
- 64K minimum RAM (typically 128K)
- Graphics chip changed to Yamaha V9938 with up to 128K video RAM, supporting 80x24 text mode, new video modes without colour attribute clashes, resolutions up to 512x212 (16 colours) and 256x212 (256 colours), more advanced sprites with 16 colours each
- Hardware acceleration for common graphics commands like fill, line, color, etc.
- Interlacing to double vertical resolution
- A vertical scroll register
- Sound chip changed to Yamaha YM2149
- Clock chip changed to RP5C01
- 3.5" floppy disk drive support
The following table lists some of the more common MSX2 machines and their specifications:
|Mfr/Model||Price||RAM||ROM||Video||Sound||Cartridge Slots||Non-standard extras|
|Philips NMS8245||128K||32K||0||720K floppy drive|
|Philips NMS8280||128K||32K||0||2 disk drives, digitizer, gen-locker|
|Sony HB-T7||64K||Built-in 1200 baud modem, external RS232C interface|
MSX2+, officially released in 1988 in Japan only but available through upgrades in other countries, further expanded the specification:
- MSX BASIC v3.0
- Disk ROM
- Kanji ROM
- Graphics chip changed to Yamaha V9958, all video RAM at 128K, support for a new high colour video mode in 256x212 with 19,268 colours, a horizontal scroll register.
- Sound chip optionally available was the Yamaha YM2413
MSXturboR (1990), was only available in Japan:
- MSX BASIC v4.0
- 4Mb of Firmware
- 512K or 256K of RAM, with 16K of S-RAM (battery-backed)
- Sound supported MIDI in/out, PCM 8-channel with built-in microphone
MSX, MSX2, and MSX2+ were all built for 8-bit home computers based around the Zilog Z80A microprocessor. MSXturboR was instead based on an enhanced version of the Zilog Z800 known as the R800. By 1990 though, the IBM-PC market was booming, so production of the Turbo R ended in 1995 due to lack of support.
All MSX copyrights are now owned by the MSX Association