TI-99/4A FAQ: Floppy Disk drives and formats

Disk formats

On the TI basic has no idea what a disk drive is. It’s the DSR in the controller that gives basic, or other software the ability to use disks. It is basically plug-and-play in 1979, pretty impressive.. Make a new storage device? basic doesn’t care, just as long as the DSR is there.  So most disk formats are logically based on the controller you have.

Ti Disk Formats 

• • 90k SS/SD 40 tracks
  • 180k DS/SD 40 tracks
  • 360k DS/DD 40 tracks
  • 360k DS/SD 80 tracks

Disks that are single density will read/write fine on double density drives.  Also the TI controllers all work fine with DS/DD 360k 40 track drives but only can read/write in their respective SD formats.

TI disk controllers:

• Texas Instruments Disk controller Sidecar
  • SS/SD 90k
• Texas Instruments Disk controller (PEB)
  • SS/SD 90k
  • DS/SD 180k
• Myarc Disk Controller (PEB and sidecar)
  • SS/SD 80k
  • DS/SD 180k
  • SS/DD 180k
  • DS/DD 360k
• Myarc Hard Floppy Disk Controller (HFDC) (PEB)
  • SS/SD 80k
  • DS/SD 180k
  • SS/DD 180k
  • DS/DD 360k
  • DS/HD 1.44mb (Geneve only HD with 32k ram chip and 9216B installed on the HFDC)
• Corcomp Disk Controller (PEB and sidecar)
  • SS/SD 80k
  • DS/SD 180k
  • SS/DD 180k
  • DS/DD 360k
• BWG Disk controller (PEB)
  • SS/SD 80k
  • DS/SD 180k
  • SS/DD 180k
  • DS/DD 360k
• NanoPEB/CF7 (sidecar) disk emulation formats supported
  • SS/SD 80k
  • DS/SD 180k
  • SS/DD 180k
  • DS/DD 360k
  • NANOPEB 800k (note: No native TI disk controller supports the nanopeb disk size, you’ll have to copy the files to a disk with a format that is supported.)

Disk Managers:

Since the storage software on the TI is DSR based there needs to be an application to format disks, copy files, duplicate disks etc..

• Texas Instruments disk manager programs
  • Disk Manager cartridge
    • supports only the format that the TI sidecar supported SS/SD
  • Disk Manager 2 cartridge
    • supports only the formats that TI supported on the PEB DS/SD controller..
  • Disk Manager 3 cartridge (prototype)
    • supports DS/DD for the unreleased DS/DD controller
• 3rd party disk manager programs
  • DM1000 was released from the Ottowa users group in the 1980s and can format up to DS/DD, special versions were created for many hardware devices including the Gram Kracker, Horizon Ramdisk and Cf7/Nanopeb.
  • DM2K is under current development and is updated regularly. It can do 40/80 track DS/DD.  current version is 3.0 and it’s the most versatile disk manager  www.ti99-geek.nl/Projects/dm2k/dm2k.html
  • GDM2K was released to give DM2K functionality on the Geneve in Mdos mode.
  • Corcomp Disk manager was included with Corcomp controllers and could be loaded from the title screen with the stock ROMS
  • Myarc Disk manager was included with Myarc controllers

Disk Emulation:

• Gotek
  • Gotek drives are inexpensive and available most places including arcadeshopper.com
  • USB flashdrive stores your images
  • Stock Gotek firmware will NOT work with TI and Geneve however,
  • Gotek has been tested with 3rd party firmware on the TI and Geneve (see below)
  • Firmware options: 
    • Flashfloppy firmware – This is the most versatile firmware.. and it is free
      • Supports a massive range of retro computers, synths, and machinery
      • Directly reads and writes many image formats
      • Flexible track layout for Raw Sector Images
      • Extremely configurable
      • Supports TI DOAD (dsk images) directly without conversion and also can use HFE format files
      • many hardware addons including speaker, various displays, rotary and other encoders for selecting disk images
    • HXC firmware 
      • all TI disk images must be converted to HFE format to be used
      • $ per drive to install
• http://hxc2001.free.fr/floppy_drive_emulator/
  • Cost varies but is around $115 + shipping from EU
  • available in SDCard and USB models
  • all TI disk images must be converted to HFE format to be used