The CP/M Interface by QL Plus Limited (an offshoot of PCML Ltd) was mentioned in the news section of QL User (December 1984/January 1985 issue) and a working prototype, designed by Robert Harvey, was said to have been demonstrated at the Compec Show at Olympia in November 1984.
This was described as an extension card containing a Z80 processor and 64K RAM which would sell at £199.
The statement by John Fuller (MD of QL Plus Limited) states that the 4MHz Z80 runs in parallel with the QL's 68008 processor, with the latter being used for fast I/O operations. The board features two ports which would be configured in software as a mouse controller and a parallel printer interface, although the company intended to release alternative software to allow them to be used as a disk controller and robotics controller.
The disk controller was designed as a piggy-back board attached to the original interface.
The news item cites Tony Tebby as having partly engineered the link between the Z80 and the QL, and W H Smith were also said to be busy converting CP/M software onto microdrive for use with the unit.
It is sadly unknown whether this interface was ever released, although more details appear in the profile of QL Plus in QL User (March 1985) and the advert by PCML in the April 1985 issue stated:
"Our New CMP 3.0 Z-80 Card will be available in June"
In an early letter from Sinclair Research (undated), listing programs available for the Sinclair QL, mention is made of CPM/80 from PCML.
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Title: QL Plus CP/M Interface
Interface Type: CP/M Emulator
Connection: QL Expansion Port
Through-Connector: No
Manufacturer: QL Plus Limited (an offshoot of PCML Ltd)
Year First Sold: Unknown
Original Price: Unknown
Download Manual: Unknown
Accompanying Software: None