Let's communicate with MSX on Windows "Joy Joy File System"

What is "Joy Joy File System"?



"Joy Joy File Server (Windows)" + "Joy Joy File System (MSX)"

Creating a connection cable

RS232 to TTL

Ready to use

PC side (Windows)

MSX side

MSX-BASIC extended command

Once the "Joy Joy File System" is installed, the following extended commands will be available from BASIC.

PC → MSX transfer command

Load the files on your PC into MSX memory or VRAM.

(Loads the one directly under the "File Serving Folder" specified in "Joy Joy File Server")

MSX → PC transfer command

Save MSX memory and VRAM as a file on your PC.

(It is saved directly under the "File Serving Folder" specified in "Joy Joy File Server")

Floppy disk command

A command to access a file on a floppy disk. I made it because I wanted something to save and load as a pure binary file without adding a header for BLOAD.

Since it only handles simple errors, it may be better not to use it for important disks (^ _ ^;)

VRAM control command

This command sets the offset of the VRAM address.

When saving / loading VRAM with the S option of a save / load command, the VRAM address that can be specified as an argument is 64KB of 0000H-FFFFH, but by setting this option to 1 in MSX2 or later, the latter half of VRAM ( 10000H-1FFFFH) can be accessed.

Command for text transmission synchronization mode

This command is used to transfer the character string entered in the text transmission window of "Joy Joy File Server" (Windows) to MSX in real time.

* Do not execute other serial communication commands while the synchronization mode is ON. When executing other commands, be sure to execute _JJINPUT (0) to turn off the synchronization mode.
* If communication is interrupted while the synchronization mode is ON, the MSX side will freeze while waiting for communication. Be sure to perform _JJINPUT (0) to end the synchronization mode before disconnecting the communication.
* Since the program for synchronous mode resides at the end of the "File control block (FCB)" in the BASIC work area, an error will occur if the maximum number of files in MSX-BASIC is 0 (MAXFILES = 0). Also, do not issue file operation commands such as OPEN or PRINT # 1 while the synchronization mode is ON (SAVE, LOAD, etc. are okay). If you really want to use it, set MAXFILES = 2 or higher before turning on the synchronization mode.

General-purpose send / receive commands

This command is for general-purpose serial communication at 38400bps.

Please use it when communicating with the terminal software or when communicating with two MSXs.

To connect two MSXs, prepare two AMP 9-pin cables, connect GND (pin 9) to each other, and then connect your own pin 1 to the other's pin 6.
Also, if both sides are waiting for _JJRECV, they will deadlock and freeze. Be careful when writing programs for two-way communication.

Debug command

Precautions when using Joy Joy File Server


It was difficult to achieve high-speed communication of 38400bps (for MSX).

Since the tuning is done at the assembler level, there is almost no error handling.

Therefore, if communication is interrupted or unexpected data is sent, it often freezes. I'm sorry (T_T)

Anyway, if you have a problem, please try pressing the [x] button of "Joy Joy File Server". If you are lucky, it may come back (^ _ ^;)

In addition, we have greatly referred to the following sites for development.


If you have any comments or questions, please contact @tiny_yarou on twitter.