Vortex Disc Drives

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Disc drives from Vortex, with 80 tracks and 720K capacity (704K available).

Vortex -S and -D Drives (720K/disk)

  • F1 - S Single 5.25" drive with NEC765, with VDOS 1.0
  • F1 - D Double 5.25" drive with NEC765, with VDOS 1.0
  • M1 - S Single 3.5" drive with NEC765, with VDOS 1.0
  • M1 - D Double 3.5" drive with NEC765, with VDOS 1.0

These are the original drives from Vortex, for use on CPC 464. The hardware supports one or two 80 track drives, additionally a 3" FD-1 can be connected as third drive, ie. unlike most other CPC disk interfaces it supports more than 2 drives. VDOS allocates RAM for only 2 drives though, which of the 3 drives are in-use is selected with |S command.

Vortex -Z Drives (180K/side or 180K/disk?)

  • F1 - Z Single 5.25" drive without FDC, without VDOS
  • M1 - Z Single 3.5" drive without FDC, without VDOS

These are the Low-Capacity drives from Vortex, for use on CPC 664/6128 or CPC 464 with DDI-1 (ie. on computers that already have a FDC and AMSDOS). There doesn't seem to be anything special about this product, just an off-the-shelf disk drive, shipped with a CPC-specific connection cable.

Although the drives might have 80 tracks (?), AMSDOS can access only 40 tracks. No info if the drives are double-sided, and if yes, if they do have a side-select switch for accessing the second side?

Vortex -X Drives (720K/disk)

  • F1 - X Single 5.25" drive without FDC, with VDOS 2.0
  • M1 - X Single 3.5" drive without FDC, with VDOS 2.0
  • F1 - XRS same as F1-X, upgraded with RS232 interface
  • M1 - XRS same as M1-X, upgraded with RS232 interface

These are the newest drives from Vortex, for use on CPC 664/6128 or CPC 464 with DDI-1 (ie. on computers that already have a FDC). The |S command (for accessing a third drive) is no longer used, the new |X command allows to swap drive A and B.

Vortex Add-ons

  • Vortex X modul (adding RS232 support to -X drives)
  • VDOS2.0 (upgrading older drives to VDOS 2.0)
  • Second drive unit (for upgrading a single -S drive to a dual -D drive)

I/O Ports

 Standard Addresses (same as used by AMSDOS):
   FB7Eh 765 FDC (internal) Status Register (R)
   FB7Fh 765 FDC (internal) Data Register (R/W)
   FA7Eh Floppy Motor On/Off Flipflop
 Special Addresses (secondary FDC):
   FBF6h 765 FDC (Vortex,ext) Status Register (Read)
   FBF7h 765 FDC (Vortex,ext) Data Register (R/W)
   FA7Eh Floppy Motor On/Off Flipflop (same as normal)
 (The Special addresses are mentioned in the manual
 for the Vortex -X drives) (but apparently they are referring
 to other/older Vortex drives, not the -X drives)

The Special addresses are used only on CPC 664/6128 and only if the Vortex drive includes an FDC chip.

The pictures of the PCB are not clear. There appears to be a jumper and a PAL type chip next to the FDC. The manual mentions a 'decoder-ROM' so perhaps this is in the PAL?


  • Note1: The -Z and -X drives do not include FDC chips.
  • Note2: The -S and -D drives do reportedly work only on CPC 464 (?).

So, not sure if/when the Special addresses are used at all? 

 RS232 Ports (for -X drives with RS232)
   FADC/FADD=Serial Data/Control
   FBDC/FBDD/FBDF=Counter 0/1/Mode.
 So it's probably compatible with Amstrad/Pace 
 (and probably also including, but not using,
 Channel B Ports FADE/FADF and FBDE).

Vortex Disk Format

Sector numbers are 01h..09h (same as AMSDOS IBM Format, but with a 9th sector). Disks are Double-Sided, Double Density, 80 Tracks, 9 Sectors, blocks are allocated in 4K units. Total capacity is 720K (704K available):

  • First 9K contain two System Tracks (eg. CP/M Bootstrap)
  • Next 4K contain directory (see Note)
  • Next 704K are data (allocated in 4K blocks) (aka 4K clusters)
  • Last 3K are unused (due to 4K allocation size)

Note: According to the manual, the directory can hold 128 entries under VDOS2.0 (whole 4K used), but only 64 entries under VDOS1.0 (only half of the 4K area used).

The Vortex -Z drives do not seem to include any VDOS ROM (so they do support only normal 40-Track AMSDOS Formats, but NOT the 80-Track Vortex format).

Pictures

  • The Vortex F1 Drives

  • F1-Z Disc Drive

  • F1-D Disc Drive

  • Vortex Disc Drive Interface (for -S or -D drives)

  • A anonymous box houses the controller

  • Look inside the controller, with 765 chip, and VDOS (upgraded to v2.0)

  • Controller with VDOS mounted

  • Vortex Disc Drive Interface (for -X drives)

  • Newer -X drive interface without 765

  • Newer -X drive interface without 765, plus RS232

Germanized-English RSX Commands and VDOS differences compared to AMSDOS

  • Vortex apparently considered the normal AMSDOS RSX commands |TAPE.xx and |DRIVE/|USER too difficult for german users, and changed them to |CAS and |SELECT (which resemble equivalent german words Kassette and Selektieren). This is making VDOS slightly incompatible with AMSDOS and all other AMSDOS clones (except for Dobbertin's X-DDOS, which supports both the english and germanized dialects).

|SELECT is used to both select user and/or drive. e.g. |SELECT,"3" for user 3, |SELECT,"B" for drive B, |SELECT "4B" for user 4 on drive B. VDOS doesn't have USER or DRIVE commands.

  • When using CAS CATALOG you give the address of a buffer to fill with the list of files in the current user and drive. The format of this data differs compared to AMSDOS.

AMSDOS uses:

<ff> <8 bytes filename> <3 bytes extension> <2 bytes size in K> with a byte of 00 to indicate the end of the list.

VDOS uses:

<user> <8 bytes filename> <3 bytes extension> <2 bytes size in K> with a byte of FF to indicate the end of the list.

This is important if you use CAS CATALOG and parse the data to fetch the list of files.

Manuals

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