I had one of the very early ones (initially without heatsinks on the Ferranti ULA chips). They were fitted on an engineer visit.

I fitted a hard disk to mine, and the top power supply overheated regularly. I always had to run it with the lid off!

It wasn''t totally IBM compatible. Because it used an 8086, with a 16 bit data path, extra logic was needed to make the 8259 interrupt controller respond on the correct ports. They didn''t do this, so where a real IBM compatible would use ports 20 and 21, the Advance only used even numbered ports$ in this case, 20 and 22. Any software that programmed the interrupt controller would not work correctly.

Advance provided a conversion program that (mostly blindly) changed 21 to 22 in executables files. Not a success. I did it by code inspection with DEBUG, and was usually successful.

@Micah B. Haber

"Internally" refers to the processing word width. In this case, 16bit words can be computed at each cycle. But it takes nearly twice as long as computing an 8bit words, save some overheard because the process is inherently serialized. That''s why 16bit computing is only marginally faster than 8bit. 16bit real advantage is for bigger address space, not speed.

On the other hand, "Externally" refer to the bus the CPU use to communicate its information to and from the system, including RAM. A 16bit bus can effectively carry twice the information of an 8bit bus and thus, is twice as fast, because here we are talking about parallel communication.

While it''s true a 16/16 system is not twice as fast as an 16/8 system, the 8bit bus of the 16/8 setup can seriously bottleneck the 16 bit CPU in some scenario. We should say then the 16/8 is slower than the 16/16, not the other way around. Todays 32 and 64bit CPU have external bus much wider than their internal address space /processing width and are not directly comparable to the 16bit CPU era.

The 86B was my first introduction to the 'PC' world after a string of home computers. It did everything an IBM junior did but was cheaper and had the 'perfect suite' of software too, which was actuall pretty good for it's day.

I remember it would regularly crash when it got warm because of poot contacts between the A and B boxes - ended up soldering the ribon cables into place to fix the damn thing once and for all!

If my memory serves - these were only available through the WHSmiths stores in the UK. Not ideal marketing as Smiths weren't big in the home or business computer markets at the time.