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Model Launch Date Notes Pictures
BETSIE and DOTTIE   Hardwired controllers used for calculating odds in bookmaking.  
SADIE 1966 Sterling and Decimal Invoicing Electronically - IBM electric typewriter with electronics built from Mullard combi-logi components. Last model was SADIE5 using DTL. Hard wired programmed.  
SUSIE 1967 Stock Updating Sales Invoicing Electronically - Basically SADIE with a drum store. Multi-SUSIE also appeared with up to three consoles.  
Mark 1 1970 Processor and core memory cabinet some 6' high by 3' wide. Front loading disk drive in right hand matching cabinet. Optional left hand cabinet for paper tape punch and reader.  
Mark 2 1973 The only water-cooled model! Lots of good ideas like fence registers. Pretty disastrous however, soon modified to emulate a Mk1  
Mark 3   The Mark 3 processor changed to allow micro-instruction combinations. For instance the LSA instruction (001700) could be extended to LSA03 (001703) to repeat the shift three times. Ten board 6Me processor set  
Mark 4   A very popular, and reliable model. The Mk 4 was the last with a wire-wrapped back plane. Although semi-conductor memory was available for this model, the Mk 4 was the last to support core memory. Still using the 10 board 6Me processor set.
Mark 5 1984 The Mark 5 was the first machine to use the new format cards and Bus. Three card processor (each card about A3 size) First machine to support bank switching memory. MOS memory with battery backup to 'fake' core. New disk controller card to support CDC Lark drives. Re-designed disk controller to support CDC Hawk drives. Construction was a mechanical disaster - generally disliked by engineers.
Distributor 1986 Replaced the big Mark 5 with a smaller filing cabinet styled machine. Functionally the same as a Mark 5. Cabinet held a single CDC Lark drive. The very smart control panel was hidden underneath the top cover.