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Canon Canola L813

Date of introduction:  1978 Display technology:  Fluorescent
New price:   Display size:  8
Size:  6.3" x 5.2" x 1.8"
 159 x 132 x 45 mm3
    
Weight:  9.6 ounces, 273 grams Serial No:  869104
Batteries:  4*AA or NiCd Pack-5 Date of manufacture:  mth 05 year 1978
AC-Adapter:  AD-1 Origin of manufacture:  Japan
Precision:  8 Integrated circuits:  TMS1045 (KTΔ7809)
Memories:  1 Displays:  Futaba 9-BT-18A
Program steps:   Courtesy of:  Joerg Woerner

Canon introduced in 1978 with this Canola L813 the successor of the Canola L812 with a similar feature set but more stylish design. Rather unusual with both the L812 and L813 is the limited calculating capability of only 8 digits, the later Canola L-3 in a slightly larger package increased the Vacuum Fluorescent Display (VFD) to 12 digits.

Dismantling the featured Canola L813 calculator manufactured in May 1978 reveals a very cost effective design using a double-sided printed circuit board (PCB) centered around a TMS1045 single-chip calculator circuit connected to a 9-digit Vacuum Fluorescent Display (VFD), a keyboard assembly using a flexible PCB and powered by 4 AA-sized alkaline batteries.

The TMS1045 is a member of the TMS1040 Product Family based on the TMS1070 "computer-on-a-chip" introduced in 1974 with the original TMS1000. While the TMS1070 can directly interface with low-voltage VFD up to 35 Volts does it still need external resistors and a zener diode to bias the anodes and grids of the display with respect to the filament. The TMS1040 added an extra VPP pin to connect a negative 30 Volts bias voltage for its modified output drivers. With the TMS1070 featuring 11 R Outputs for the Digits, 8 O Outputs for the Segments and 4 K Inputs for the Keyboard, reduced the TMS1040 the number of R Outputs to 9, consequently are all known TMS1040 calculator designs using a 9-digit VF Display.

Looking closer onto the PCB you'll notice five diodes labeled D1 and placed somehow between the TMS1045 and the keyboard assembly - at first glance an unusual approach. Preparing our DCM-50A Platform to allow the Characterization of Single-Chip Calculator Circuits of the TMS1040 Family, we reverse-engineered the Canola L813 calculator and understood that Texas Instruments started to add with the TMS1040 a "virtual" 5th Keyboard Input line by using two additional diodes emulating the 5 K Inputs of the TMC0980 Family. While the TMS0100 single-chip calculator circuit introduced the concept of an 11x4 keyboard matrix scanned with the 11 Digit Outputs and 4 Keyboard Inputs, would the reduction to just 9 Digit Outputs of the TMS1040 allow for only 9x4 keys and switches, in some calculator applications like the Canon F-31 a show-stopper. Adding an extra "virtual" Keyboard Input allows consequently for a 9x5 keyboard matrix and this Canola L813 arranges its 22 keys within a 9x4 grid and uses one Keyboard Input for both the 5-position [+ 4 2 0 F] and 2-position [  AM] sliding switches and a "Diode Jumper" as an "Always-on" switch to select certain software features embedded in the TMS1045 firmware.

The Unisonic Model 1040-1 calculator using with the TMS1044 another product of the TMS1040 portfolio sports only 27 keys and an hard-wired power [on/off] switch but nevertheless makes use of the "virtual" 5th Keyboard Input line. And don't miss the Brinlock Model 806 for the true champion in the TMS1040 league.

Don't miss the Canola L813 II replacing the [+/-] and [RM], [CM] keys with [M+], [M-], and [RM/CM] keys. 



If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, December 5, 2001. No reprints without written permission.