BASIC Programming with the N: Device

The N: device is a standard CIO device, which means it can be used directly from Atari BASIC and other platform BASICs. Once the NDEV handler is loaded, you can load and save programs, read and write data files, and open direct connections to TCP and UDP sockets – all from BASIC.

Prerequisites

Before using the N: device from BASIC, ensure:

1. The NDEV handler is loaded (you should see FUJINET READY at boot)
2. Your FujiNet is connected to WiFi
3. You are in BASIC (not the DOS menu)

For details on loading the handler, see the N: Device Overview.

Loading BASIC Programs

The simplest way to use the N: device is to load and run BASIC programs directly from the network.

Using a Full Devicespec

RUN "N:HTTP://ATARI-APPS.IRATA.ONLINE/BLACKJACK.BAS"

This downloads BLACKJACK.BAS over HTTP and runs it immediately. BASIC supports devicespecs up to 128 characters in length, so most URLs will fit without issue.

Using a Directory Prefix

For repeated access to the same server, set a directory prefix first using XIO call 44. This matches the same call used by MyDOS and SpartaDOS and works regardless of which DOS is loaded:

XIO 44,#1,0,0,"N:HTTP://ATARI-APPS.IRATA.ONLINE/"
RUN "N:BLACKJACK.BAS"

The prefix HTTP://ATARI-APPS.IRATA.ONLINE/ is automatically prepended, so N:BLACKJACK.BAS resolves to the full URL.

You can also use the NCD tool to set the prefix before entering BASIC.

Saving BASIC Programs

Save programs to network file systems the same way you would save to disk:

Direct Save

SAVE "N:TNFS://HOMESERVER/PEWPEW.BAS"

Save with Prefix

XIO 44,#1,0,0,"N:TNFS://HOMESERVER/"
SAVE "N:PEWPEW.BAS"

File I/O Operations

Since the N: device exposes a full CIO interface, you can use all standard BASIC I/O commands to interact with network resources.

Reading a File

10 REM -- Read a file from a web server
20 OPEN #1,4,0,"N:HTTP://EXAMPLE.COM/DATA.TXT"
30 TRAP 100
40 INPUT #1,A$
50 PRINT A$
60 GOTO 40
100 CLOSE #1

Writing a File

10 REM -- Write data to a TNFS server
20 OPEN #1,8,0,"N:TNFS://HOMESERVER/OUTPUT.TXT"
30 PRINT #1,"Hello from Atari BASIC!"
40 PRINT #1,"Written via FujiNet N: device"
50 CLOSE #1

Read/Write Mode

Open a channel for both reading and writing by setting aux1 to 12:

OPEN #1,12,0,"N:TCP://192.168.1.8:2000/"

TCP Socket Communication

The N: device allows BASIC programs to communicate directly over TCP sockets. This enables everything from simple chat clients to BBS terminal programs.

Simple TCP Client

10 REM -- Simple TCP echo client
20 DIM A$(256),B$(256)
30 OPEN #1,12,0,"N:TCP://192.168.1.100:6502/"
40 PRINT "Connected! Type text to send."
50 PRINT "Press RETURN to send, ESC to quit."
60 REM -- Main loop
70 TRAP 200
80 INPUT B$
90 IF B$="" THEN 80
100 PRINT #1,B$
110 REM -- Check for response
120 STATUS #1,A
130 IF A=0 THEN 80
140 INPUT #1,A$
150 PRINT "Received: ";A$
160 GOTO 80
200 CLOSE #1
210 PRINT "Disconnected."

Connection Flow

flowchart TD
    A["OPEN #1,12,0,"N:TCP://host:port/""] --> B[Connection Established]
    B --> C{User Input}
    C -->|Text entered| D["PRINT #1,B$"]
    D --> E["STATUS #1,A"]
    E --> F{Data waiting?}
    F -->|Yes| G["INPUT #1,A$"]
    G --> H[Display response]
    H --> C
    F -->|No| C
    C -->|ESC pressed| I["CLOSE #1"]

UDP Communication

UDP is useful for sending small, quick messages – for example, in multiplayer game scenarios.

Sending UDP Packets

10 REM -- Send UDP data to another FujiNet
20 OPEN #1,8,0,"N:UDP://192.168.1.50:5000/"
30 PRINT #1,"HELLO FROM PLAYER 1"
40 CLOSE #1

Receiving UDP Packets

10 REM -- Listen for UDP packets
20 OPEN #1,4,0,"N:UDP://:5000/"
30 TRAP 100
40 STATUS #1,A
50 IF A=0 THEN 40
60 INPUT #1,A$
70 PRINT "Received: ";A$
80 GOTO 40
100 CLOSE #1

Working with HTTP

Downloading Data from a REST API

10 REM -- Fetch data from an HTTP API
20 DIM A$(256)
30 OPEN #1,4,0,"N:HTTP://API.EXAMPLE.COM/TIME"
40 TRAP 100
50 INPUT #1,A$
60 PRINT A$
70 GOTO 50
100 CLOSE #1

Downloading a Binary File

For binary files, use GET instead of INPUT to read raw bytes:

10 REM -- Download a binary file via HTTP
20 REM -- and save it to disk
30 OPEN #1,4,0,"N:HTTP://SERVER/GAME.COM"
40 OPEN #2,8,0,"D1:GAME.COM"
50 TRAP 200
60 STATUS #1,A
70 IF A=0 THEN 200
80 GET #1,B
90 PUT #2,B
100 GOTO 60
200 CLOSE #1
210 CLOSE #2
220 PRINT "Download complete."

IOCB Open Modes Reference

The aux1 parameter in the OPEN statement controls the access mode:

Common Patterns

Error Handling with TRAP

Always use TRAP to handle end-of-file and network errors gracefully:

30 TRAP 100
...
100 REM -- Error/EOF handler
110 CLOSE #1
120 IF PEEK(195)=136 THEN PRINT "END OF FILE"
130 IF PEEK(195)=138 THEN PRINT "TIMEOUT"
140 IF PEEK(195)=200 THEN PRINT "CONNECTION REFUSED"

Checking Connection Status

Use STATUS to check how many bytes are waiting before reading:

STATUS #1,A
IF A>0 THEN INPUT #1,A$

Setting the Directory Prefix from BASIC

Use XIO 44 to set the N: device prefix without leaving BASIC:

XIO 44,#1,0,0,"N:HTTP://MY.SERVER.COM/FILES/"

This is equivalent to running the NCD tool from DOS.

Tips and Best Practices

Next Steps

• N: Device Overview – high-level introduction
• Supported Protocols – detailed protocol reference
• Tools and Utilities – NCD, NCOPY, and other tools