Technology
The 130 was Canon’s first electronic calculator, designed by a team new to this kind of product. It’s interesting to see how some questionable design solutions were arrived at, and the changes that were made for later models.
Electronics
Canon 130 Calculator Internal, left and backplane
The 130 is fully solid state with over 500 Ge transistors and over 1500 diodes. An accurate count has not been made due to the production engineering features discussed below. The electronics are spread over nine single-sided boards.
The electronic implementation is counter-based, where all information is held in 4-bit counters, one counter per displayed digit. Arithmetic is based on stepping these counters up or down, in a similar fashion to mechanical calculators. This is a logically simple design which may have appealed to a novice design team, but it is expensive in hardware, particularly when the counters must be constructed from discrete transistor flip-flops with (at least) two transistors per flip-flop.
The incandescent displays must be individually driven, each digit. Multiplexing is impossible due to the relatively slow speed of incandescent bulbs. This imposes the electronic cost of a driver transistor per digit (13 places x 12 displays = 156 driver transistors!) and a construction cost of a massive 150-plus wiring harness to connect the displays with their respective digit drivers.
Memory
The 130 is somewhat unique in that it has no discrete working storage, no core or delay line as found in many other machines. This is because working storage is inherent within the counter architecture and temporary storage of machine flags and status is provided by some additional flip-flops.
Production Engineering
The entire calculator is highly engineered with a robust pressed metal case, internal chassis and card cage with many brackets and fasteners. The PCBs have detailed silkscreens to identify signals. Despite this, there are some troublesome design decisions:
Inaccessible PCBs
The card cage is mounted on a baseplate that has a raised rim and the rim prevents PCBs from being removed from the cage, unless the cage is first removed from the baseplate. This would be a major service technician frustration.
Soldered Backplane
Canon 130 Calculator Logic boards soldered into backplane
The logic PCBs are mated to a backplane PCB with nicely-punched slots and wire-spring contacts that connect from the backplane to the PCBs. This looks like a home-grown but nice enough substitute for regular PCB edge connector sockets, perhaps motivated by the same philosophy that preferred home-designed displays to nixie tubes.
Unfortunately, this solution turns out to be a servicability headache, like the display modules. The Contact fingers are soldered at both ends, so the logic PCBs are in fact soldered into the backplane with their components inaccessible unless the board is desoldered. Similarly, it’s not possible to test a logic board by putting to on an extender unless one does multiple cycles of desoldering and resoldering.
This machine is a servicability nightmare