Hardware – Floppy Drive

Drive Replacement for a REAL Model I/III/4

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

Floppy-80 for a REAL Model III / 4NGA

Click to Enlarge

For those out there with a Model III or Model 4 (NGA), Patrick Bureau of Texas Tandy Restorations is selling a hardware board called the Floppy-80.

The Floppy-80 is designed to replace entirely internal drives and external drives with a single SD card. It cannot be used in conjunction with real floppy drives, but can be used in systems that do not have floppy controllers.

The Floppy-80 board plugs directly unto the motherboard 20 pin edge connector that normally be used to connect a flat ribbon cable to the floppy disk controller (and +5v from a molex) that will let you mount DMK disk images (or HFE as read-only) on the fly on drives :0 :1 :2 and :3 and use the images as if they were real diskettes inserted into your TRS-80. .ini files can be prepared to set the 4 drives to a preconfigured configuration.

One of the other main features/benefits of the Floppy-80 is that you can set up .INI files which populate the drives, and can switch between those .INI files on the fly. You can also designate an .INI file which will be the default.

A utility for use in the TRS-80 is included and allows for the following additional commands:

Get the Floppy Drive Controller status, including displaying all mounted DMK images
Display a directory of the root folder of the SD Card to show what DMK files are available to you for mounting
Select a INI file to be the default
Mount a disk image
Import a file from the SD Card
Export a file to the SD Card

An example of the commands would be that if you type FDC MNT OS-M3-MULTIDOS-531.DMK 2 at your TRS-80 DOS prompt, the DMK file OS-M3-MULTIDOS-531.DMK will then be mounted as :2

The Floppy-80 supports the following DOS’s for Drive 0

Model 3

LDOS v5.31
NEWDOS/80 v2.0
Z’DOS v1.0

Model 4 NGA

TRSDOS v6.21
LDOS v6.31
CP/M v2.2
NEWDOS/90 v2.0

The Floppy-80 board is sold both as a kit and fully assembled and tested – reach out to TexasTandyRestorations@gmail.com for info.

HxC Floppy Drive Replacement for a REAL Model I/III/4

The SDCard HxC Floppy Emulator designed by Jean-Francois Del Nero, emulates a 34 pin floppy drive and treats DSK and DMK images which are stored on a SD card as actually floppy disks. To be clear, this product is designed to be mounted in/on an actual TRS-80, as a drive on the floppy cable.

It can emulate one or two drives, and disk images are mounted using the three buttons on the lower right, which are NEXT, SELECT/EJECT, and PREVIOUS. The filenames are shown on the LCD, which comes in a variety of colors.

Current features of the SDCard HxC Floppy Emulator are:

  • Modes Supported: Shugart and PC
  • Two floppy disk drives emulation
  • 5V +/- 10% standard power floppy connector input
  • 3 LEDs (“Power LED”,”Floppy access LED”,” SDCard access LED “)
  • 3 buttons (“Next”,”Select/Eject”,”Previous”)
  • 1 audio transducer
  • 2*16 chars Alphanumerical LCD (LCD and buttons can be put on an external front panel)
  • SD Card up to 2GB / SDHC Card supported up to 32GB
  • FAT32 supported. Subdirectory and long name file supported
  • Track mode based floppy emulator (Full track pre-encoded in the HFE image file)
  • Write support: ISO MFM 256/512/1024 Bytes sector write supported, ISO FM/SD 128/256/512/1024 Bytes sector write supported.
  • Bitrate support: 250/300Kbits/s (DD floppies), 500Kbits/s (HD floppies)
  • RPM support: 300, 360
  • Tracks / Side support: Up to 256 tracks per floppy, 1 or 2 sides.

The documentation can be found here and the changelog can be found here.

MXS (TRS-80 Modular eXpansion System) for the Model I

Click to Enlarge

The TRS-80 Modular eXpansion System (MXS) designed by Jay Rounceville, consists of up to four modules set up as a stackable set, starting with the base module which will give you a 32K and supplies the power that the other boards use. On top of this you can add the floppy drive emulator module. Other modules include a Texas Instruments video/graphics board and/or a WIFI board.

Schematics and overview can be found at https://github.com/calphool/TRS80MXS.

Leave a Reply

Your email address will not be published. Required fields are marked *