• Higher performance of most frequently used tests
  
• New Test: MR impedance measurement
  
• New Test: NLTS vs. Write Current
  
• Other modifications
  
• Bugs fixed
  
• Appendix A
  

Higher performance of most frequently used tests

The overall performance of most frequently used tests is now 1.3-2.5 times faster. Our measurements showed higher throughout the whole WITE system:

See Appendix A for details of test conditions.

MR impedance measurement test

The MR Impedance measurement test is a part of WMRTESTS module (Tests|MR Tests|MR-Impedance menu). It provides impedance measurements of an MR element under specified Read Bias current. The result can be different from measurement done by multimeter because some MR elements change its impedance depending on Read Bias current. Both regular and dual stripe MR heads are supported.

Hardware Requirements. To be able to measure resistance of MR element:

- customer using true MR Amplifiers (TI, SSI, VTC, ...) should connect new Universal Interface assembly G1 and a pair of new head amplifiers from the list:


CXA3080	ASSY.B
PSA4005	ASSY. B
SSI1560/61/62	ASSY. D
TLS24306	ASSY. B
TLS24774	ASSY. B
TLS24806	ASSY. B
TLS24506	ASSY. A
TLS25006A	ASSY. A
VM61612	ASSY. A

Any new MR amplifier with BHV (Buffered Head Voltage) will also be supported.

- customer working with Guzik type MR Head Amplifier should use new Universal Interface assembly G2 and a pair of new mixed MR head amplifiers from the list:


VM61210 + 2412MRRM

M61814 + 2412MRRM

Any new mixed MR head amplifier can be designed with this feature by customer request.

Dual stripe measurement mode reports two impedances for dual stripe MR head. This mode can be enabled by checking the corresponding check-box in Confogure|Preamp mrnu.

MR amplifiers must be calibrated by measuring 2 reference resistors approximately equal minimum and maximum expected MR head impedance.

The calibration form under Calibrate|MR-Impedance looks as follows:

The calibration procedure looks as follows.

1. Select the head amplifier 0.
2. Plug in the first reference resistor in place of the head.
3. Put the exact value of the resistor.
4. Measure the impedance.
5. Plug in the second reference resistor in place of the head.
6. Put the exact value of the resistor.
7. Measure the impedance.
8. Save the results.
9. Select the head amplifier 1 and repeat steps 2-8.

New NLTS vs Write Current Test has been added

This test measures non-linear transition shift (NLTS) as a function of write current. The requirements, configuration, algorithm and output of this test are almost identical to those of the Alternate Spectral Elimination test (known also as Fifth Harmonics test, see PRML/NLTS tests manual).

NLTS vs Write Current Test Configuration:

Typical plot of NLTS vs. Write Current for the Mflx units system:

The following parameters are written to the NLTSV5 result table database:

Other modifications

• Ignore runtime grading failure option has been enforced when running Monitor Production test.

• In the WROffset test a new result TrackWidth has been introduced. User can specify the amplitude threshold at which the width is to be calculated.

• Ability to select head order in production test was implemented. Formerly, if production sequence heads 0,1,2,3,6 were chosen (head stack case), production sequence would be performed exactly in this order: heads 0,1,2,3,6. A customer can change the head order in production sequence, e.g. 3,0,6,1,2 and the tests will be performed for heads in that order.

• One-touch access to "Operator Panel" controls has been added.
  Operator's access to the buttons in the Operator Panel dialog box is now implemented more easily. In addition to standard accelerator keys used by pressing two-key combinations of Alt + underscored symbol, in same cases just pressing of underscored symbol will be enough. For two controls, Config and Start Production, if the focus does not belong to any edit control (that means beam-type cursor is invisible) then the required command can be triggered by pressing ‘N’ or ‘S’ respectively instead of Alt-N, Alt-S.

• The behavior of the mouse 'drag_n_drop' operation on most Grid controls, ( e.g. test sequence in a production configuration) has been corrected so that while dragging the selected row remains visible as it is sliding up and down.

• The ability to add user-defined identification fields to operator panel is now supported. Currently new added fields don't appear in any report.

Bugs Fixed

• System couldn't start a spinstand normally if the initial RPM specified was less than 459.

• If a Monitor Production test changed the ASCII file output to a different filename, then all subsequent Production tests (non-Monitor) sent their results to the same 'Monitor' results file. Now it restores the filename as soon as the production mode gets back from the 'Monitor' to the 'non-Monitor'.

• If a lot of records are selected in history database, while the result processor is in standalone mode then clicking the "View" button may trigger a GP error. The configuration grid now is modified to allow multiple row display.

Appendix A

The measurements were provided with the following set of equipment:
RWA 1632, S312MP, RPM 4500 and 7200, trackwidth 250 µIn, M/R head with W/R offset approximately 20 µIn,
Pentium-90Mhz, 16Mb RAM, Windows95. UseFastWrite option was checked in Parametric test setup. It accelerates Write Flux operation in Overwrite test.

Sample_production test. Four zones have been configured:

Zone1: (Tracks 0 - 800)	W/ROffset 3 iterations, range from -90 to +30 µIn, step 7 µIn, measure forward only, amplitude threshold = 100%, skew angle = 0; Parametric test 3 iterations, Overwrite and PW50 enabled.
Zone2: (Tracks 801 - 1500)	TAAStability 60 iterations, Write option: Pattern, Gated stability enabled.
Zone3: (Tracks 3001 - 3333)	TAAStability 60 iterations, Write option: Pattern, Gated stability enabled.
Zone4: (Tracks 1501 - 3000)	W/ROffset 3 iterations, range from -47 to +40 µIn, step 7 µIn, measure forward only, amplitude threshold = 100%, skew angle = 0; Parametric test 3 iterations, Overwrite and PW50 enabled; TAA Asymmetry 3 iterations, Preconditioning: None, WriteOption: Pattern, TAABoth, TAAPos, TAANeg are disabled.

W/R Offset test: see Zone1 configuration.
Parametric test: see Zone1 configuration.
TAA Stability test: see Zone2 configuration.
Frequency test: 10...60 MFlux range with step 5, 1 iteration.
Overwrite test: 40 iterations without W/R offset (as it was an inductive head).
Result Processing: 200 output results were provided.