LSI Advert - November 1982
From Practical Computing
A 16-bit and an 8-bit micro all in the same compact unit
LSI, which sometimes made the claim to be the UK's biggest micro manufacturer, is back with an update to its System M-Three - a machine which was also popular as an OEM model, showing up as the British Genius and the Caltext micro.
This time, the System M-Four adds to the earlier Z80A of the M-Three with an Intel 8088 - a nominally-sixteen-bit chip but which only had an eight-bit data bus, making it slower than it could have been.
There's also an update to the Z80, with a faster 5MHz Z80B, which gave the M-Four compatibility with the huge range of regular eight-bit CP/M software on the market.
Meanwhile, the 8088 supported CP/M-86 and the multi-user MP/M-86 - which on the M-Four meant up to three concurrent users - as well as LSI's own LSI Net and Microsoft's MS-DOS.
It was also one of the new wave of machines making use of DMA, or Direct Memory Access.
This was a way of allowing disk drives to move data in and out of system memory directly, rather than going via the central processor - thus making the machine significantly faster when using floppies or a hard disk.
The System M-Four retailed from £2,150 plus VAT, which is around £12,400 in 2026.
Date created: 20 March 2026
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