An MSX in your browser: the MSX1, MSX2 and MSX2+, with cartridges, a
tape deck, a disk drive, FM sound and a modem. Everything you load
stays in this browser for next time.
Open the page and press a key or click the screen: the MSX switches on (browsers only allow sound after that). Tick Power on by itself in the Machine panel to skip this next time.
The built-in machine is C-BIOS, a free MSX system ROM. It starts cartridges but has no BASIC, so with nothing in the slots it says No cartridge found.
Drop a game (.rom, or a .zip with one inside) anywhere on the page. It goes in slot 1 and the MSX restarts with it.
For MSX BASIC, load the ROM of a real machine (next chapter).
Speed runs the MSX at 2x or 4x (sound is muted then). Region picks 60 Hz (NTSC, as in Japan
and Brazil) or 50 Hz (PAL, Europe) on an MSX1; an MSX2 BIOS sets it itself.
2Choosing the machine
The System ROM menu decides which computer you have. The three C-BIOS machines are built in;
ROMs of real machines are copyrighted, so you load dumps of your own and they stay in your browser.
You load
You get
Files
Nothing
C-BIOS MSX1, MSX2 or MSX2+: runs cartridges, no BASIC
Built in
An MSX1 BIOS
MSX BASIC: Gradiente Expert 1.0 or 1.1, Sharp Hotbit, any MSX1
One 32K file, such as expert_1.1_basic-bios1.rom
An MSX2 BIOS
MSX BASIC 2.0, 80 columns, SCREEN 5-8
Main ROM and SUB-ROM together (two files, or one zip)
The Brazilian MSX2+ kit
Your Expert or Hotbit as an MSX2+: BASIC 3.0, the MSX2+ logo, 512K, and MSX-MUSIC if its SUB-ROM has it
A main_2p_… ROM and a sub_2p_… ROM together
Loading a BIOS
Click Load BIOS… under System ROM.
Pick the file, or for an MSX2 or MSX2+ both files at once (hold ⌘ or Ctrl to select two), or a zip with both.
It joins the System ROM menu and the MSX restarts with it. Switch machines from the menu any time; Remove forgets the one selected.
3Cartridges and the shelf
Click a slot or drop a file on the page to load a cartridge (.rom, .mx1, .mx2, .bin, or a .zip). The ⏏ takes it out.
Every cartridge, tape and disk you load goes on the shelf under the slots. Click one to put it back in slot 1, or its 2 for slot 2; × takes it off the shelf.
Big cartridges switch banks of memory, and makers did it differently. Ok-Prompt guesses the scheme from the code; if a game does not start, pick another in the menu under its slot: Konami, Konami SCC, ASCII 8K, ASCII 16K.
Games that save (role-playing games with battery-backed memory) need ASCII 8K + 8K battery RAM or ASCII 16K + 2K battery RAM in that menu. Their saves stay in the browser and come back with the cartridge.
Loading from a link
A link can bring the files with it, so a site can say "play this in your browser":
cbios, cbios2 or cbios2p (MSX1, MSX2, MSX2+), or the file name of a BIOS you loaded
Join them with &. Your browser fetches each file from its site, which has to allow it
(GitHub and archive.org do, many ROM archives do not); if not, the slot says so, and you can download the
file and drop it in instead.
4Keyboard, paste and joysticks
Keys type what is printed on your PC keyboard: symbols and accents go through the key table of the BIOS
in use, so a Brazilian keyboard types ç, ã and " correctly on an
Expert. Letters, arrows and Space keep their MSX places for games. The Keyboard setting can put
every key in its MSX place instead.
Keys the PC does not have
GRAPH
Left Alt
CODE
Right Alt (accents on Brazilian MSXs)
STOP
F7 (CTRL+STOP: Ctrl+F7)
SELECT
F8
F6-F10
Shift + F1-F5
Numeric keypad
The PC's keypad
Joysticks and the mouse
Arrow keys and Space work in most games. A gamepad is joystick 1: plug it in and press a button.
Joystick port 1 (Settings) can hold an MSX mouse instead, for drawing programs. Click the screen to take the pointer; Esc gives it back. The left and right buttons are the mouse's.
5Tapes
Click the tape deck or drop a .cas or .tsx file. The deck shows the first file on the tape and its kind.
▶ Load (with a BIOS that has BASIC) restarts the MSX and types the right command for you. Or type it yourself:
BLOAD"CAS:",R (machine code), CLOAD then RUN (BASIC), RUN"CAS:" (BASIC as text).
⏮ rewinds; the number beside the tape is how far it has played.
＋ Blank inserts an empty tape: CSAVE"NAME", SAVE"CAS:NAME" or BSAVE"CAS:… record on it, and ⤓ downloads it.
6The disk drive
A disk drive needs the disk ROM of a real drive (it holds Disk BASIC and MSX-DOS, which are
copyrighted). Load yours once and it stays in the browser. How disk drives worked, and the Brazilian
models, is in the history page.
Setting it up
Under Disk drive in the Machine panel, click Load disk ROM… and pick the ROM (16K, or a zip with it). The MSX restarts with a drive.
Two drives appear under the tape deck, A: and B:. Drop a .dsk on the page (it goes in A:) or click a drive; ＋ Blank inserts an empty 720K disk. On the shelf, a disk's B puts it in drive B.
Games on several disks ask for the next one: eject and put it in drive A:, from the shelf or the drive's button. Copying between disks works across A: and B:.
An MSX1 has no clock, so the disk ROM asks for the date as it starts, as a real one did. Type it the way it asks (some want day-month-year, some month-day-year), or just press Enter.
You get Disk BASIC. A disk with MSXDOS.SYS and COMMAND.COM on it boots MSX-DOS instead.
Disk BASIC in five commands
FILES
Lists the disk
SAVE"NAME"
Saves the program (LOAD"NAME", RUN"NAME" bring it back)
BLOAD"GAME.BIN",R
Loads and starts machine code
KILL"NAME.BAS"
Deletes a file
CALL FORMAT
Formats the disk: answer A, then any key
7Sound and FM music
The MSX's own sound chip (three tones and noise) always plays; Konami SCC cartridges add their five wave channels.
FM sound (MSX-MUSIC), in the Sound panel, puts the Yamaha YM2413 FM chip in the machine, as in the FM-PAC cartridge and the MSX2+ machines. Games that know it play their FM music. Switching it restarts the MSX.
With the MSX2+ kit's com_fm SUB-ROM the chip is built in, with its FM-BASIC: CALL MUSIC, then PLAY #2,"CDEFGAB".
The volume slider is in the Sound panel; sound starts after the first click or key on the page.
8Save states
The four slots under Save states (Machine panel) each keep the whole machine: memory, chips, cartridges, the tape and the disk where they are.
Save stores the MSX as it is now; saving over a used slot asks first. Load brings it back, BIOS, disk ROM and cartridges included, exactly where it was.
A state needs its BIOS and disk ROM still loaded in the browser. States are kept in this browser only.
9The printer
LPRINT "Hello" and LLIST print on the paper in the Printer panel.
⤓ Download saves the printout as a text file; Clear starts a new page.
10The modem and the AI board
Put ☎ Ok-Modem from the shelf into a slot.
With MSX BASIC type CALL TERM; with C-BIOS the terminal starts by itself. On an MSX2 it shows 80 columns.
ATI lists the BBSes, ATDT 1 calls the first one. You hear the dial tone and the handshake.
ATDT DEEPSEEK calls the AI board: chat with the sysop or the BOFH, or order a BASIC program; it arrives on your tape for RUN"CAS:".
CTRL+STOP (Ctrl+F7) goes back to BASIC.
11What the browser keeps
Your BIOS and disk ROMs, the cartridges in the slots and on the shelf, the tape, the disk, battery saves,
save states, settings and the MSX2 clock's memory stay in this browser, on this computer. Nothing is
uploaded. Clearing the site's data (or a private window) starts afresh, so download tapes and disks you
want to keep.
12Where to find software
Most MSX software, and every real machine's BIOS and disk ROM, is still copyrighted. Ok-Prompt ships
none of it: what you load is your own business. The cleanest sources come first.
Free or legal
C-BIOS: the free MSX1, MSX2 and MSX2+ BIOS, already built in.
MSXdev: the yearly contest for new MSX games. Its entries are homebrew, usually free to download.
Project EGG: official re-releases of Japanese computer games, MSX among them (paid, mostly in Japanese).
Your own machine and cartridges: dumping what you own is the surest way. openMSX's setup guide explains system ROMs and dumps.
Community archives
File-Hunter: the largest MSX archive: games, tapes, disks, system ROMs; some publishers allowed their titles there.
MSXPro: Brazilian, strong on Brazilian machines, BIOS versions and disk interfaces.
MSX Resource Center: news, the MSX wiki, and downloads of homebrew and tools.
Generation MSX: a catalogue of every MSX release (what exists, who made it, which machine it needs), with no downloads.
These archives host copyrighted files too; for many titles that is a grey area.
What Ok-Prompt reads
Cartridges
.rom, .mx1, .mx2, .bin
Tapes
.cas, .tsx
Disks
.dsk (360K or 720K)
System ROMs
An MSX1 BIOS (32K); an MSX2 or MSX2+ main ROM with its SUB-ROM
Disk ROMs
Plain 16K dumps (not the DDX, TPX or DMX board EPROMs)
Any of them
Inside a .zip
13When something does not work
A game shows a black screen or restarts: try another bank scheme in the menu under its slot.
No sound: click the page once; check the volume, and that Speed is Normal.
A tape game does not load with ▶ Load: it needs a BIOS with BASIC; C-BIOS cannot load tapes by itself.
The disk ROM is refused: it is probably a board EPROM dump that does not read as a disk ROM; use a plain one (see The disk drive).
BASIC answers Invalid date at start-up: the disk ROM is asking for the date; type it in the order it shows, or press Enter.
The MSX2+ comes up in 32 columns:SCREEN 0:WIDTH 80:SET SCREEN.
Keys type the wrong symbols: switch the Keyboard setting between Types what your keys say and MSX key positions.
Ready?
Load a BIOS, drop in a cartridge, a tape or a disk, and type PRINT "Olá, MSX".