TWO COOL® Frequently Asked Questions

Q: What is the SUM method of depreciation?
SUM stands for the sum-of-years-digits method of accelerating depreciation. The following quote from an accounting textbook describes how to calculate SUM: "To use sum-of-years-digits, one first determines the total amount to be depreciated: amount to be depreciated (Y) = asset cost - salvage value. Next, the number of years over which depreciations is to occur is determined, and the sum of these years is calculated: for N years the sum is 1+2+. . .+N = X. Then the amount of depreciation for each of the N years is determined as follows:

First year depreciation = Y*(N/X)
Second year depreciation = Y*((N-1)/X)
Continue until the last (Nth year), when
Final year depreciation = Y*(1/X)

Source: E.E.Adams and R. J. Ebert, Production and Operations Management, Prentice-Hall, 1982, p.668.

The downloadable spreadsheet has an example. Fortunately, TWO COOL® does all these calculations automatically. The overall COO does not change as depreciation is just the method of allocating book value over the depreciation life of the equipment. But the deprecation charge (first line of the 7 year table) will show the impacts of the different depreciation schedules.

Click here to download the example spreadsheet

Q: How do I include post-warranty maintenance personnel costs in TWO COOL® other than by contract?
Since TWO COOL® sums all costs over the useful life of the equipment, timing of expenditures is not a major driver. Thus enter the time weighted average of warranty and post-warranty maintenance technicians by shift into the "Maintenance Cost" section. For example, if the warranty only covers unscheduled maintenance for 2 years, equipment life is 7 years, and a minimum of 2 technicians are required, use the following formula:

UM=(2 techs X (7-2 years))/7years = 1.43 unscheduled maintenance techs

If the warranty is 1 year, but the equipment user requires that 1 of his technicians be assigned in addition to the 2 technicians provided under warranty, use the following formula:

UM=((1 tech X 2 years)+(2 techs X (7-2 years)))/7 years = 1.71 techs

Either formula can be directly entered in cells F144 through K144 of the single column model, depending on the number of shifts to be covered.

Q: Are any special considerations needed when creating TWO COOL® models for subsequent use in PRO COOL®?
PRO COOL® process cost analysis software uses TWO COOL® cost of ownership software to estimate the cost of a sequence of process steps or a cluster of process tools. PRO COOL® reads the 13 TWO COOL® cost drivers from the COO model summary along with yield and utilization information. The use of COO summary information can lead to differences in the way PRO COOL® and TWO COOL® respond as utilization or throughput rates are changed. These differences can be minimized the taking the following precautions in constructing COO models specifically for use in PRO COOL®:

Enter material, consumable, and utility costs as a cost per unit (wafer, package, or mask) rather than as an annual cost. (For further information see PRO COOL® Technical Alert #5, "PRO COOL® vs. TWO COOL® Comparison."

Enter software development costs, including test software:

• if development costs are in currency (per year) enter as "Annual Software Contract per    System"
• if development costs are in hours (per week) enter as "Personnel/System: Engineers"

Input a typical throughput rate for the test cell as the initial module throughput rate in COO models used for PRO COOL® for Sort and Test.

In all cases differences are minimized as TWO COOL® utilization and throughput inputs approximate PRO COOL® conditions.

Q: Sometimes I cannot open TWO COOL® Help screens under Microsoft Windows 3.1. Why?
Even though a computer running Windows 3.1 may have a large amount of DRAM memory, all applications must use some memory in the systems resources area (the first 640K). If that portion of memory is fully used, Windows 3.1 will disable the Help function to prevent system problems. Closing other applications will often allow Windows 3.1 to access Help. In rare cases, TWO COOL® must be closed (saving any open models to the database) and Windows 3.1 must be restarted. Remaining system resources can be monitored by checking the Program Manager: Help: About Program Manager screen. If system resources are not greater than about 25%, then the Help files are not allowed to open. Microsoft provides no warning or error message to indicate that insufficient system resources may be the problem.

Q: My database shows up in the drop down window but TWO COOL® says there are no files to retrieve?
There are two causes of this problem.

Make sure you are selecting the correct model type. The Model Type of the TWO COOL® file must match the Model Type that has been requested to be retrieved. For example, if you have chosen to retrieve a Type 1 model, models of Type 2, 3, or 4 will not be displayed.

The use of some special characters in the database name, such as a hyphen, are interpreted by Excel as command codes. Renaming the database should cure the problem.

Q: When I try to print COOLDOC.exe the printer does not print all the pages.
In the FILE:PRINT dialog box select "Print Text as Graphics". This will prevent the printer from interpreting bitmaps as fonts.

Q: I am using a non-American version of Excel. Some of the TWO COOL® dialog boxes won't run.
This is a bug in Excel. The macros for TWO COOL® are written in international format. However, there are some formats which Excel hard codes, such as currency, time, and date.

To cure this problem in Windows, open "Control Panel" from "Program Manager" and select "International". Change the Currency Format to Symbol = $, Symbol Placement = $1, and Negative = -$123,22.

To cure this problem on a MacIntosh, open the "Numbers" control panel and set Number Format to "U.S.".

Q: Sometimes I get an error message when I use the Model Choices dialog box to open a new model type.
If you use the File button on either the Reports, Charts, or Sensitivity Analyses dialog boxes you need to save the file to the same subdirectory (folder) where TWOCOOL.XLM resides. If you save to another location, then the Excel directory pointer will not be looking where the Model Choices dialog box expects. If you want to save files to another location, move them after quitting TWO COOL®.

Q: When I exit TWO COOL®, all other open Excel files are closed.
TWO COOL® closes all open Excel files. The exit warning message allows an opportunity to save open Excel files including non-TWO COOL® files prior to quitting. This issue was resolved with version 2.1.1 and higher. Contact WWK about upgrading to the latest version of code.

Q: When I re-installed TWO COOL® on my PC after upgrading versions of Excel, I get an error message.
Insure that the TWO COOL® directory structure is intact. COOLDATA must be a subdirectory to the directory containing TWOCOOL.XLM.

Q: I have a site license. Can TWO COOL® be installed on a PC network?
With a site license, TWO COOL® can be downloaded from a network server to user computers using File Manager. Insure that the TWO COOL® directory structure remains intact. COOLDATA must be a subdirectory to the directory containing TWOCOOL.XLM.

Q: When I open TWOCOOL.XLM from the Excel list of the last opened files I get an error message.
PC users must use the Excel File:Open command. All other ways of opening TWOCOOL.XLM may cause the file links to be lost. Macintosh users can simply double-click on the TWOCOOL.XLM icon.

Q: When opening TWO COOL® in Excel 5.0 I see a message at the bottom of the screen that says Excel 4.0. Is TWO COOL® compatible with Excel 5.0?
A major enhancement included in version 2.0 is the ability to use Excel 5.0. The files provided are in Excel 4.0 format and can be run unaltered on either Excel 4.0 or 5.0. If you are using Excel 5.0, the database files will automatically be saved in Excel 5.0 format. If you wish to share your database files with an Excel 4.0 user, you will need to manually resave the database files in Excel 4.0 format prior to transfer. The only differences in operation between Excel 4.0 and 5.0 are charts in Excel 5.0 have a gray background and some text in dialog boxes may be shifted horizontally.

Q: When I try to exit TWO COOL® Excel tries to run MSEXCEL4.XLM.
During installation of Delrina Winfax, one or two files may be placed into the XLSTART subdirectory (MSEXCEL4.XLM and/or MSEXCEL5.XLM). These files allow faxing directly from Excel. Unfortunately, these files contain auto_close macros which interfere with the shut down process of TWO COOL®. To prevent this conflict, move MSEXCEL4.XLM and/or MSEXCEL5.XLM out of the XLSTART subdirectory when using TWO COOL®.

Q: Sometimes I get multiple dialog boxes on the screen at the same time. Though only one is active.
Windows allocates memory for system functions such as screen refresh to fixed size "heaps." Should the "heap" reach its maximum, dialog boxes may remain on the screen after they have been executed. This can cause confusion as to which box is active. This phenomena can be minimized by closing all open programs and windows prior to starting Excel from the Program Manager.

Q: When I print a report my printer outputs extra pages that are blank or contain only a few characters.
TWO COOL® provides two print width options. The "Print Narrow" choice is used when "Print Wide" generates extra blank pages or causes small amounts of text to spill onto adjacent pages. Some Texas Instruments and Hewlett Packard printer drivers may print extra pages regardless of the print width selected. These printer drivers are based on the HP Laserjet IIIsi format. Use of the TI Microlaser PS23 or equivalent HP driver should eliminate the problem.

Q: I am installing an update to my software. I am concerned that I might overwrite my database files.
When installing TWO COOL®, make sure to backup your current database files. If you install the new version in the same folder (subdirectory) as your current version, your database files may be overwritten. Once the installation is complete, you can copy your database files back to the COOLDATA folder (subdirectory).

Q: I would like to use a formula to calculate an input value instead of just entering a fixed number. Can I do this in TWO COOL®.
TWO COOL® allows user defined formulas in input cells to be saved in the database. Formulas are treated the same as any other input values and require no user intervention in the save routine. Be extremely careful when saving formulas to the database. Cell locations are not the same between the one and two column versions, nor between columns in the two column version. Use absolute references and use the data in the same file and column from which it was originally saved.

Q: I am trying to input formulas in the dialog box mode. Why doesn't this seem to work?
Formulas can only be entered into input cells in the spreadsheet and menu operating modes. The dialog mode does not allow formula input and will convert existing formulas to values. This will cause existing formulas to be overwritten.

Q: Where should I input lot set-up time?
Lot set-up time is a throughput issue. When determining the number to input in "throughput at capacity," you must include your assumptions about lot set-up time and the product volume processed between set-up procedures. Throughput at Capacity = 60/(processing time/wafer+lot set-up time/wafers run between lot set-ups) where all times are in minutes.

Q: I used the Excel File:Save command to save my data. How do I retrieve it?
TWO COOL® does not use the File:Save function to save data. Use the COOL:Database command to save all or part of your input data. To retrieve your previous work use the Excel File:Open command to open the spreadsheet you saved. Make sure TWO COOL® is open and simply copy and paste your values into the model. Once this is done, use the COOL:Database function to save the data.

Q: Are there any suggestions on strategies for naming files in the database?
A systematic approach to naming database items is critical. You may decide to put everything in one database or you may have separate databases for data types, customers, suppliers, sites, etc. Data files should use the same name that was used in the "Model" input in the informational input section. Since the database report function is keyed on the "Model" name input, you can easily match the report output to the data file. While the databases are limited to eight character names, the data files have no such limitation. Be descriptive when naming your data files.

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