Dobbertin Harddisc

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Dobbertin Logo

A harddisc manufactured by the German company Dobbertin.

One of the first ways to connect a Harddisc to the CPC. The Dobbertin harddisc has a capacity of 20 MB. The disc was partitioned in four partitions of 5152 KB each. It was delivered with drivers for CP/M (2.2 and CP/M+) and allows up to 512 directory entries for each partition (including date and time stamps under CP/M Plus). It's even possible to boot CP/M Plus from the hard disc.

Reviewed in Amstrad Computer User.

Pictures

  • Dobbertin 20 Mb Harddisc

  • Dobbertin 20 Mb Harddisc

  • Dobbertin 20 Mb Harddisc interface

  • Interface Top

  • Interface Bottom

  • Interface PCB Top

  • Interface PCB Bottom

  • Inside 1

  • Inside 2

  • Inside 3: PSU

  • Inside 4: XT controller

Disc

  • Dobbertin HD Interface Driver Disc

  • Driver disc side A

  • Driver disc side B


Software using the Dobbertin Harddrive

  • In addition a lot of (cracked) games are able to run from the HD-20 hard disc

Technical

Dobbertin HD20 probably uses a modified pc-xt interface which uses a Winchester type hard disk. The WD1002-SHD datasheet describes a basic set of commands. The status register values are outputs from the chip itself. But here you can find the list of commands, their parameters and results. The other link describes more extensive Winchester commands extending the WD1002. The actual Winchester implementation in the HD20 is not known.


Uses XD-DOS v2.10 (which supports the harddisc, and additionally supports external double sided 80 track disc drives). The 20 MB harddisc is split into four partitions, with drive names D, E, F, and G (drive name C isn't used here, but may be used as RAM disc, in combination with Dobbertin RAM expansion). Under FutureOS the four partitions are named I, J, K and L. The hard disc is controlled by this I/O Ports: 

 #FBE0  Dobbertin Harddisc Data Port
 #FBE1  Dobbertin Harddisc Status, Reset
 #FBE2  Dobbertin Harddisc Select, Configuration
 #FBE3  Dobbertin Harddisc DMA, Interrupt
 #FBE4  Dobbertin Harddisc Reset

The hard drive interface is an PC-XT compatible hard disc interface. The CPC's port mappings are close to the PC-XT's port mappings.

Other harddisc solutions for the CPC

Modern:

Promo (summary) (english)

  • Controller: Seagate ST11M XT-controler.
  • Harddisc: 20 MB (3.5" Seagate, NEC, Kyocera, or Miniscribe)
  • X-DDOS 2.10 (selectable in ROM bank 1-7)
  • 4 Partitions of 5152 KB (5 MB) (accessible as Drive D: to G:)
  • 512 Directory entries per partition
  • support for CP/M 2.2 with 63K TPA (requires 128 KB RAM), and for CP/M Plus
  • support for Softwareclock and TIMEROM+ (Real Time Clock under CP/M Plus)
  • Price: DM 1100.-

Promo (german)

  • Dobbertin Festplatte

  • Frontpage

  • Contents

Downloads

Links

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