Mark V - BCL Molecular 18

BCL Molecular 18
Go to content
Molecular Mk V

A new cabinet was designed by BCL to hold the new three-board processor and it's PCB backplane.
I can only surmise it was designed to match the CDC Hawk drives that were typically being sold with the Mk V.  Horrible to work on for engineers!!

from Keith Howlett:
"While this was going on it was apparent the ABS were not doing too well making the M18.  I had looked at re-engineering the processor and went to Munnelly with a proposition. I would re-engineer the M18 onto 3 boards with a printed backplane thus halving the cost of the system.  

The deal was I would fund development and if I was successful I would have the exclusive production rights for the first 25 machines and own the copyright unless and until he bought it out by paying the development costs.  I did all the design and drawing work single handed, Geoff Boote gave a hand at the end with some debugging of noise problems.  I designed the Quad I/O and transferred the Hawk controller to a single PCB from the former 2 board controller.  The large format core memory was already well tested as I had been using it as service spares to replace the unreliable Fabritek for some time and selling upgrades.  I got the idea after I got a contract to repair stuff for EMI medical and was supplied with a Data General machine.  I quickly realised that the DG hardware was pretty much identical to the M18, even many of the instructions could be directly translated.  I "borrowed" a memory card and rigged it up on my 6ME bench rig and with a few tweaks had it working.  BCL designed the MK 5 cabinet which was a dogs breakfast.  

Once that lot was successfully in production I turned my attention to updating the disk drives as the Hawk was on notice that the production was ending.  I reckoned that a totally new disk controller was beyond my capabilities ( or I was too busy with the growing business) and approached John Adams who designed the new Lark controller to my spec.  I also designed and developed the bank switching.

In due course I went back to Munnelly with my design for the distributor cabinet which was accepted."
BCL supplied Mk 5 chassis to Systemation in batches of five.  Systemation installed the hardware and commissioned the system.
(C) 2022 Kevin Murrell & The National Museum of Computing
Back to content