Drive Replacement for a REAL Model I/III/4

This page covers the modern hardware which can be used to replace Hard Drives in a real TRS-80.

  • FreHD:  Hard Disk Replacement (uses SD Card)
  • Hard Disk Adapter Board:  Hard Disk adapter Board (needed for a Model I)
  • Hard Drive Replacement for a REAL Model I/III/4

    Frédéric Vecoven and Ian Mavric have developed, designed, and now sell a Model I and Model III/4 hard drive replacement called FreHD. The FreHD is a circuit board which accepts a SD card and looks like an actual hard drive to a TRS-80 Model I/III/4.

    DOS’s Supported:

  • Model I: LDOS 5.3.1
  • Model III: LDOS 5.3.1
  • Model 4/4P: LS-DOS 6.3.1, Montezuma CP/M 2.2
  • Additional Information:

  • Model I: Requires Model I hard disk adapter board (below)
  • Diskless Systems: A version now exists for Model III/4 systems which are cassette only
  • Model 4P: Can auto-boot from the FreHD without needing a floppy drive.
  • TRS32 Emulator: Starting with v1.28, registered copies of Matthew Reed’s Model I/III/4 emulator “TRS32” can read and write hard drive images used by the FreHD hard drive adapter, allowing PC manipulation of the drive which can then be used in the real TRS-80.
  • Purchase Options:

    • Kit A:  

    Just the bare PCB and a CD of dropbox data and is best suited to hard-core electronics enthusiasts who have the equipment to program GAL and PIC chips. All parts need to be supplied by the builder, and a complete BOM list is provided.

    • Kit B:  

    The PCB, and programmed GAL and PIC, SD card socket, battery holder, and a CD dropbox of data. This kit suits people capable of soldering together a project kit of some complexity. All parts apart from the PCB, GAL, PIC, SD socket and battery holder need to be supplied by the builder, and a complete BOM is provided.

    • Kit C:  

    Fully assembled kit, tested, partitioned and loaded with DOS ready to plug into your Model III, 4, 4D or 4P. Boot floppy disk provided. Just connect it to a 5V power source, a hard drive cable, and boot the floppy.

    • Cable:  

    To connect the emulator or a regular TRS-80 hard drive to a Model III/4/4D/4P (NOTE: if you already have a TRS-80 hard drive you don’t need this cable).

    Additional Information:

  • Knowledge Base (DOC)
  • Utilities Instructions (DOCX)
  • RSHARD6 Setup Instructions (PDF)
  • How to Build the FreHD Hard Drive Emulator – Page 8 of TRS8Bit Volume 8, Issue 1
  • Mounting FreHD in a Model I Disk Drive Case – Page 51 of TRS8Bit Volume 8, Issue 1

  • General, and ordering, information can be found on Ian Mavric’s freHD page.

    Videos:



    Compares the FreHD with an actual TRS-80 MFM Hard drive


    Shows what comes with Kit C, how to connect it and get booted up


    Shows CP/M 2.2 running on FreHD


    Shows 4P auto-boot LS-DOS 6.3.1 and CP/M 2.2


    Shows FreHD working on the TRS-80 Model I


    Self booting without floppy disks and a menu to choose a DOS image


    FreHD M1 mounted in a Dragon external disk drive case


    FreHD in a diskless (cassette based) Model III

    TRS-80 Model I Hard Disk Adapter Board

    TRS-80 Model I’s require an adapter board to adapt the 40-pin connector on the Model I Expansion Interface to a 50-pin connector for hard drives.

    Since these boards are virtually impossible to find today, Ian Mavric has created an adapter board, so those with Model I’s can connect to a real TRS-80 hard drive or a FreHD Hard Drive emulator.

    The cost for the fully-assembled board (including the TRSHD15/DCT and TRSFRM15/CMD drivers) is $50.00 + Shipping.

    The ideal system is a 48K Model I Disk system (in good condition) running LDOS v5.3.1 with a TRS-80 5MB or 15MB Hard Drive.

    Contact Ian on ianm@trs-80.com

    1 Comments

    1. Hello Ian,

      I have a Radio Shack Model 4 Microcomputer and would like buy a real TRS-80 hard drive or a FreHD Hard Drive emulator (boot-rom) as seen on your video and have it installed on my RS Model 4. Let me know the cost. Thanks.

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