Victor 9000 User Port SD Card Interface

Overview

This project enables the Victor 9000 to interface with an SD card via the User Port using a Raspberry Pi Pico. The Pico acts as a bridge between the Victor 9000 and the SD card, allowing MS-DOS 3.1 to read and write files as if it were a standard storage device.

The project consists of:

• A custom PCB that connects a Raspberry Pi Pico to the Victor 9000 User Port.
• A DOS device driver for MS-DOS 3.1 on the Victor 9000.
• Firmware for the Raspberry Pi Pico to handle SD card operations.

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Features

• Read and write FAT16/FAT32 formatted SD cards.
• Accessible as a drive letter under MS-DOS 3.1.
• Uses the Victor 9000 User Port for communication.
• Low power consumption – powered directly from the user port.

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Hardware Requirements

Required Components

• Victor 9000 running MS-DOS 3.1.
• Custom PCB
• Raspberry Pi Pico.
• SD card slot.
• SD card formatted as FAT16 or FAT32.

See the schamtic for Victor 9000 User Port to Raspberry Pi Pico Pin Mapping

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Software Installation

1. Flash the Raspberry Pi Pico Firmware

   1. Connect your Pico to a PC via USB.
   2. Hold the BOOTSEL button and power on the Pico.
   3. Drag-and-drop the compiled firmware (user_port_pico.uf2) onto the RPI-RP2 drive.

2. Install the MS-DOS Device Driver

   1. Copy the Victor 9000 DOS driver (SDDRV.SYS) to the system drive.
   2. Edit CONFIG.SYS to include: DEVICE=userport.sys

3. Reboot the Victor 9000.

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Usage

Accessing the SD Card

Once the driver is loaded, the SD card will be assigned a drive letter (e.g., E:). You can then use standard DOS commands:

DIR E:
COPY C:\FILE.TXT E:
DEL E:\OLD.TXT

Formatting an SD Card

The SD card must be formatted with FAT16 or FAT32. Use a modern PC to format the card before inserting it into the Victor 9000. You'll also need a Victor formatted disk image loaded on the card.

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Troubleshooting

Driver Not Loading

• Ensure userport.sys is in the root of your boot disk
• Check CONFIG.SYS syntax.
• Verify the Victor 9000 User Port connection.

SD Card Not Detected

• Ensure the SD card is FAT16/FAT32 formatted.
• Check the Pico firmware is flashed correctly.
• Verify the Victor 9000 User Port wiring.

Credits

• Hardware & Software Development: Paul Devine
• Many thanks to profdc9 at the VCFED forums who provided the code that got me started you can find it here: https://forum.vcfed.org/index.php?threads/ms-dos-driver-for-an-sd-card-connected-via-a-parallel-port.41516/
• Many thanks to Educardo Casino for his Openwatcom DOS driver https://github.com/eduardocasino/dos-device-driver which I incorported.
• Victor 9000 Background info and help: Many thanks to Bitsavers, Disk Blitz and the folks at the AppleSauce discord for patiently explaining to me lots of background; FozzTexx for his help in understanding some of the Victor 9000 hardware; FreddyV, Polpo, and the folks at the Retro Pico discord for letting me lurk over their shoulders; and Intergalactic for finding the hard disk struct documentation!

For questions or contributions, feel free to open an issue or submit a pull request.

I'm releasing this under the GPL-v2 as the source code I've incorporated utilized that licensing scheme.