Physical description
Digital Memory module, or Portable Memory Key, equivalent in type to a USB stick, black plastic with sliding mechanism to protect 8 copper contact strips with a digital memory area at one end. Stamped into the memory area part number "109 13858 512K KDM", indicating it had a memory storage of 512Kb. Above the number are the remains of a white bar-code label. Has as key type appearance.
.1 - Numbered in white numerals "08330705"
.2 - ditto "120703350"
Advised by Adam Chandler 20-11-2017:
They were used by tram and bus drivers. The PM (portable memory) key was issued to each driver. At the start of a shift, the driver would put it into a cream-coloured terminal at the sign-on point (starter's office in the depot) and transfer their shift information onto the key. Once the driver reached the vehicle, they put the key into the black-coloured terminal (tram driver's keypad - TDKP or bus driver's keypad) to upload the shift data to the vehicle.
This was also the method used to transfer the 'blacklist' of periodical passes that had been stolen or misappropriated to each vehicle. IE if an annual Metcard had been stolen, once the holder reported it to Metcard they would blacklist the ticket number and this would be sent out to every depot and piece of equipment. From memory there were 100 slots in the blacklist.
When a tram driver was finishing their shift (either being taken or running in) they would transfer all of the validations and ticket sale information to the PM key by inserting it a few minutes before the end of shift and downloading all of this data from the vehicle. They would then be required, on arriving back at the starter's office, to insert the key in the cream coloured terminal once more and copy all of the information across to the main system.
Bus drivers also issued tickets from their BDKPs so the black PM key was also used for ensuring the accounting information was copied across to the main system.
My memory might be faulty but I recall using them at railway stations with the Booking Office Machines (for starting and finishing shifts). No transfer of ticket issuance data however, as there was a computer equipment cabinet at each railway station with a DSL or cable link back to the OneLink central computers (in the revenue clearing house)
I don't know what happened with the MTH cars on the Stony Point rail line but I could presume that there was a cabinet with a TDKP equivalent in it and a similar procedure for start and finish of shift.
