Dobbertin Harddisc

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

Dobbertin HD Interface Driver disc (zipped .DSK files)

Software using the Dobbertin Harddrive

Cosmos
Dobbertin CP/M Plus
FutureOS using all four partitions (I, J, K and L)
MAXAM II
Prowort via using Dobbertin CP/M Plus (partitions D, E, F and G)
X-DDOS (v2.10)

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

Technical

Dobbertin HD20 is a relative of the Winchester type hard disk. There is a CPC interface which connects to a PC-XT interface.

The OMTI 5510 appears to be very close in terms of operation and commands, but the Dobbertin is probably not this. The command descriptions and operation appear to be the same although the software seems to only use TEST READY, READ, WRITE, SEEK (parking), SET PARAMETERS and FORMAT.

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 (read/write)
 #FBE1  Dobbertin Harddisc Status (read), Reset (write)
 #FBE2  Dobbertin Harddisc Select (write), Configuration (read)
 #FBE3  Dobbertin Harddisc DMA, Interrupt (Used on CPC???)
 #FBE4  Dobbertin Harddisc Reset (read or write will reset)

(Exact port decodings to be confirmed; the GALs probably describe it)

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.

To format the hard disk you need to use the CPM based system tools. To use the tools you need to patch a CPM+ disc so that it recognises the hard disk.

The disc format appears to be CPM/AMSDOS based, with 0x0e5 as the format data byte.

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

GAL16V8_IC6 (.JED File)
GAL16V8_IC11 (.JED File)