One standard for home computers, built by dozens of companies, so a cartridge or a tape bought for one brand ran on all of them. It ruled Japan, Korea and Brazil in the 1980s, and it is the machine Ok-Prompt emulates.
MSX was conceived by Microsoft for the Japanese market and pushed by Kazuhiko Nishi of ASCII Corporation. It was announced in June 1983 (sources give both the 16th and the 27th), and the first machine, the Mitsubishi ML-8000, went on sale on 21 October 1983.
The idea was the one VHS had brought to video: a single specification that Sony, Panasonic, Yamaha, Philips, Toshiba, Canon, Sanyo and many others would all build to. A cartridge works in any MSX; a tape saved on one loads on another. Microsoft called it "an attempt to create unified standards" for home computers.
Every MSX1 is the same handful of chips, which is exactly why software moved between brands. Ok-Prompt emulates each of them.
AB at their start.MSX was the leading home computer of the 1980s in Japan, South Korea, Argentina and Brazil, and fairly popular in the Netherlands and Spain. Yamaha sold whole networked classrooms (teacher machine plus student machines) to schools in the USSR, Cuba and Arab countries.
It never took off in the US, where only Spectravideo and Yamaha tried briefly, or the UK, where it arrived late (September 1984) and dearer than the Spectrum, Commodore 64 and Amstrad.
How many were sold is disputed: from about 4 million (Nishi) to 9 million (other estimates).
On 29 October 1984 Brazil passed Lei 7.232, the Política Nacional de Informática: the market for micro and minicomputers was reserved for companies with Brazilian capital (the reserva de mercado), overseen by the SEI. Foreign machines could not simply be imported; computers were made at home, often as local versions of foreign designs. The reserve lasted until the early 1990s (sources say 1991 or 1992).
MSX arrived that way, twice in one week. The Sharp Hotbit HB-8000, made by Sharp's Brazilian subsidiary through its Epcom division in the Manaus free zone, came out in November 1985: the first Brazilian MSX. The Gradiente Expert XP-800, shown at the Informática '85 fair in São Paulo, followed on 1 December 1985 at Cr$ 4.640.000 (about US$470).
Between them, MSX "virtually killed" the other 8-bit computers in Brazil. Magazines such as Micro Sistemas, CPU MSX and MSX Micro printed listings and reviews, and kits from companies such as DDX later turned Experts and Hotbits into MSX2 and MSX2+ machines. The community never left: Clube MSX still prints a magazine, and MSXRio meetings ran for years.
A home-stereo look with a separate keyboard (QWERTY with ç, a numeric pad, GRAPH and CODE labelled LGRA and RGRA) on its own connector. No CAPS lamp, no reset key. Often called a copy of Panasonic's National CF-3000; msx.org notes Gradiente was not an official MSX licensee.
Gradiente never made an MSX2 and left MSX in 1990.
One-piece case with a QWERTY keyboard with ç, 64 KB of RAM, PAL-M TV output, a Centronics printer port and optional 5¼" drives. msx.org says it "followed MSX standards strictly".
Production ended in 1988.
Brazil used PAL-M: PAL colour on a 525-line, 60 Hz picture, like NTSC. So Brazilian MSXs are 60 Hz machines, with game music at Japanese speed rather than the slower European 50 Hz.
The table mixes what the sources say with what we measured by running the original ROMs in Ok-Prompt (marked measured).
| Expert 1.0 | Expert 1.1 (and DD Plus) | Hotbit 1.1 | |
|---|---|---|---|
| Start-up text | MSX BASIC versão 1.0 Br · Gradiente | MSX BASIC versão 1.1 Br · Gradiente | HOT-BASIC versão 1.1 · EPCOM [Z.F.MANAUS] 1985 |
| Free memory | 28815 bytes measured | ||
| ç and Ç | On codes 60h and 7Eh, in place of ` and ~ measured | On 87h and 80h, as on every other MSX measured | 87h and 80h measured |
| ã, õ and other tilde letters | On the codes other MSXs use for ä, ö, ü… measured | B0h–B7h, the international MSX places (BRASCII) measured | The international places too (ã on B1h) measured |
| Keyboard table | The international layout; ç and Ç only appear because the font draws ` and ~ that way measured | A real ç key; " on Shift+2; accent keys; ã é õ also on CODE combinations measured | ç key; accents typed with accent (dead) keys, like a typewriter measured |
| Date format (BIOS ID) | Month/day/year measured | Day/month/year measured | Month/day/year measured |
| SCREEN 0 | White on black, not the standard dark blue measured | White on blue measured | |
| Other quirks | Text starts one column in measured; a hidden credits screen (below) | DD Plus BIOS identical, byte for byte measured | Starts with CAPS on, which also capitalises ç measured |
The 1.0 put the Portuguese letters wherever it could: ç and Ç on two
ASCII codes, the tilde letters on the umlaut codes. Text written on a
1.0 came out as ` and ä elsewhere, and
programs printing ` or ~ showed ç on a
1.0. Gradiente recalled most XP-800s, swapping the ROM for 1.1 and
changing nine keys, which is why most "Expert 1.0" machines today
really have 1.1. Version 1.1 moved the letters to the codes that
became BRASCII, which ended the accent incompatibilities
between makers.
Comparing the two ROMs in Ok-Prompt: 580 bytes differ, in 84 places, most of them in the keyboard routines and the key table (20 of its 288 entries).
Ok-Prompt's sibling, A-Prompt, emulates CP/M on the same Z80 core. The two standards attacked the same problem from opposite ends, and met in MSX-DOS.
CP/M (Gary Kildall, 1974) made software portable across
hardware that differed: each maker wrote a small BIOS, and every
program talked to the BDOS through CALL 5. By 1982 it
was licensed for more than 450 kinds of machine.
MSX made the hardware the same, so programs could even go straight to the chips. But it needed a disk system too. In August 1983 Microsoft hired Tim Paterson, the author of 86-DOS (which became MS-DOS), to write a "Z80 MS-DOS". He reasoned it should run CP/M programs directly. MSX-DOS 1.00 is dated 20 June 1984.
The result is a hybrid: MS-DOS outside, CP/M inside. Programs load at
0100h and call 0005h like CP/M programs; the
FCB calls are CP/M 2.2's; WordStar, Turbo Pascal and Microsoft's M80
and L80 were, in principle, compatible. But disks are FAT12, readable on a PC, and the
command line is a COMMAND.COM, not a CCP. MSX-DOS 2 (1988) added
subdirectories, and Nextor carries it on today.
| CP/M 2.2 | MSX-DOS 1 | |
|---|---|---|
| Standardises | The operating system | The whole machine |
| CPU | 8080 or Z80 | Z80 |
| Layers | BIOS · BDOS · CCP | MSX BIOS · MSXDOS.SYS · COMMAND.COM |
| System calls | CALL 5 | CALL 5, CP/M's numbers plus more |
| Programs | .COM at 0100h | .COM at 0100h |
| Files | FCBs, 8.3 names | FCBs, 8.3 names |
| Disks | Each maker's format | FAT12, as MS-DOS |
| Screen | Whatever terminal: ADM-3A, VT52… | VT52-like codes; 40 columns on MSX1 |
What did not carry over: CP/M programs set up for another terminal's codes, and anything that needs 80 columns, which came with MSX2.
Konami made the MSX a games machine: Knightmare (1986), Gradius (called Nemesis in Europe, 1986), Nemesis 2 (1987). From 1987 Konami's cartridges carried the SCC, a sound chip with five channels of 32-byte waveforms, conceived with Toshiba in 1986; fifteen games used it. Ok-Prompt plays it.
Hideo Kojima's first game, Metal Gear, came out on the MSX2 on
13 July 1987, and the first two Metal Gear games are MSX games. In
Brazil, software houses sold programs in Portuguese: one 1987 Micro
Sistemas ad lists more than 150 titles for MSX and the TK-90X.
Ok-Prompt loads .cas tapes and types
BLOAD"CAS:",R for you.
Ok-Prompt boots the free C-BIOS, which starts cartridges. To meet MSX
BASIC, an Expert or a Hotbit, load a dump of your own machine's ROM
under System ROM: they are copyrighted and not included. Then
type PRINT "Olá, MSX".
tests/real-bios.test.ts).