ICL One Per Desk / BT Merlin Tonto
OPD Accessories
Here is a brief summary of the accessories available for the OPD and Tonto.
Common accessories include
ROM and RAM packs, data communication adaptors and third party disc interfaces.
Please refer to the
storage solutions page on the RWAP Services web site.
OPD Expansion Units
A number of expansion units were developed for the OPD. BT created the DCU (Data Comms Unit) which provided enhanced high speed serial connections and a simple terminal emulator.
In recognition of the limited memory capability of the OPD, ICL and PCML developed memory expansion packs which added an additional 128K of RAM and effectively tripled the free memory ('store') available for end user applications.
ICL developed the MEU (Memory Expansion Unit), a large bulky unit with four memory slots, an enhanced version of Psion Xchange and a serial port. PCML later developed a much more compact enhanced ROM pack called the Telestore which boasted 128K of extra store memory, Psion Xchange 2.5 and between four and six memory slots.
OPD Disc Drive Interfaces
PCML and Computer One developed add on disc interfaces for the OPD, to overcome the unreliability and limited storage of the QL inspired microdrives. The Computer One interface is the simplier of the two.
- PCML Teledrive 3.5"
disc unit
- Computer One disk interface
Disc Interfaces
New Computer One Disc Interface!
 One of our traders, RWAP Services, have expressed interest in re-releasing
the Computer One disc interface for the OPD. The main weakness of the OPD are the microdrives, and this interface slots into one of the memory expansion slots on a two or four slot ROM pack and provides reliable storage on up to two double density (720K) disc drives. If you would like
to support this exciting project, please
sign the RWAP guestbook.
Disc and Microdrive
Media
Double density (720K) floppy discs, OPD compatible drives and microdrive
cartridges are available through QUANTA
traders and QUANTA shows.
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PCML Teledrive
PCML developed a number of innovative disc interfaces for the QL.
In 1987, PCML released the Teledrive disc interface for the OPD.
The Teledrive is equipped with two 3.5" 720K drives, and has
the capacity to run two additional shugart drives.
There are some important differences between versions 1 and 2 of the Teledrive firmware. Earlier models are identified by black disc drive units, the presence of a 'Teledrive' logo and the absence of a green status led on the front panel.
Applications such as
Teletoolkit and CP/M applications only run under version 2 of the firmware, but it is possible to upgrade version 1 Teledrives by swapping the on board Eprom chip.
CP/M emulation, RAM Disc and QL and PC compatibility
The
Teledrive is able to read and write MSDOS format discs and run CP/M
applications such as Wordstar.
In contrast to the simpler Computer One disc interface, the Teledrive is in effect a separate computer with it's own Z80 processor and a 256K RAM disc, and one is able to transfer data and applications between main memory, disc and the RAM disc.
The Teledrive makes the OPD much more usable and enables easy transfer of files with a PC or QL.
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