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 [=adve_040|British Genius and the Caltext micro].

This time, the System M-Four adds to the earlier [!Z80|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 [[2500|1982]] in [[now]].