Text and Images Copyright (C) 2006, 2007 Mike Sebastian

Walgreens' Corner Office ATC-139 Graphing Scientific Calculator

Walmart blazed the trail with the twenty dollar Durabrand 828 graphing calculator in June, 2006. In late July, 2007, Walgreens began offering their own twenty-dollar graphing calculator - the Corner Office brand ATC-139.

A quick examination indicates that the ATC-139 is functionally identical to the SC-1376 version of the Durabrand 828. The differences between the two models are purely cosmetic. The layout and pitch of the keyboards are identical. The displays are identical. The cases are virtually the same size. The differences include some slight differences in the colors of the keys. The the case is dark grey in color, which makes some of the black legends printed near most of the keys very difficult to read (see image below).

Like the Durabrand 828, the ATC-139 is just barely a graphing calculator, with a postage stamp sized 35 by 23 pixel graphing region on the left half of the display.

Forensics result for the ATC-139. The forensics algorithm produces a result of 8.999999998078897 - a 16-BCD-digit result.

So, what do you get in a $20 graphing calculator? You get:

• LCD: 35 by 23 pixel graphing, 11 characters (the first 6 character postions overlap the graphing region), plus 3 characters for a scientific notation exponent or program steps remaining.
• 50 key keyboard (including the 4 positions of the 4-way rocker key).
• 26 memories (A-Z), plus an ANS (last answer) memory.
• 400 program steps, divided among up to ten program areas (P0-P9).
• Programming constructs: goto, conditional branching, looping (DSZ, ISZ), 9 levels of subroutines.
• The normal arithmatic functions, common and natural logarithms, trigonometric functions in three angular modes, hyperbolic functions, sexigesimal conversions, polar-rectangular coordinate conversions, binary/octal/hexadecimal support, and single and two variable statistics.
• Formula algebraic logic for entry of calculations.
• 16 BCD digits of precision.
• Powered by a single CR2032 lithium coin cell, estimated by the manufacturer to provied 300 hours of operation.
• Slip-on cover to protect the display and keyboard when the calculator is not in use.

This calculator also comes with a 52 page instruction manual. Most of the text in the manual appears to be printed in a 4-point font, so it is a little difficult to comfortably read.

My biggest complaint about this calculator is the black keyboard legends printed on the dark gray case, making them very difficult to read. In other words, if you really want a cheezy twenty dollar graphing calculator, get the Durabrand 828 because you can at least read the keyboard legends.

The Corner Office ATC-139 graphing calculator. Corner Office is a trademark of Walgreens. The calculator is imported by East West Distributing Company. Note that the packaging says "Comparable to TI-83." Both the ATC-139 and TI-83 are graphing calculators, but that is as far as the comparison can go. Functionally, the ATC-139 is not even close to the TI-83. Don't be fooled!

The Corner Office ATC-139 out of its packaging.

A close-up of two portions of the keyboard shows the poor color choices utilized on the keyboard of this calculator. Notice how the black keyboard legends and entries in the mode reference table (top) are barely visble against the dark grey of the calculator case. Also notice the color discrepancies between the MODE, SHIFT, and ALPHA keys and the respective pink (mode), blue (shift), and green (alpha) keyboard legends.

The internal view of the ATC-139. Construction is fairly typical, with the chip protected by a blob of epoxy (chip-on-board), and a heat seal conductor connecting the PCB to the display. Of interest are some of the notations on the PCB. The model is identified as SC-1418. The design date on the PCB is February 26, 2007. The PCB revision is 1.0. What I believe is the chip part number, is YXF10046-1. (Compare these notations to those on the image below.) Disassembly is extremely easy. The battery cover is held by a single screw, with an additional six screws holding the two halves of the case together. The main PCB is held to the front of the case by five screws. The PCB of the SC-1376 version of the Durabrand 828 is very similar to this ATC-139 PCB.