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.
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
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.
• 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.
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).
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.