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Exercise-Tapes-Ron2b0-Operating

From: ghiselli < jghiselli@sbcglobal.net >
Date: Fri, Oct 25, 2019 4:59 pm
To: Pat Buder < pbuder@acm.org >
Cc: ...

Hi Pat, Carl, etc. I updated the "Exercise Tapes, Ron 2.0" program. It's now called "Ron 2.1" (it didn't seem a big enough change for a 3.0). Previously, if one tape got a persistent write error, the program would keep trying that tape drive to achieve a good write, ignoring the other tape drives. Now, "Ron 2.1" will continue to service other tapes as well. I thought Ron Williams' original code was pretty good, and I hope he is resting well and from on high approves this change. I created three copies of "Ron 2.1", tested them, and put them in the demo program racks. The operating procedures don't change. There are still a couple copies of "Ron 2.0" for anybody who doesn't like to change. Just because I was idly interested, I did some calculations of our tape capacities. Ron 2.1's printed statistics show that the program can write about 8,500 one-thousand-byte records before hitting end-of-reel on the shortest tape (then it rewinds all tapes and does another pass). A 1000-byte block at our "High Density" (556 bpi) should take 1.8 inches of tape The inter-record gap is nominally 0.75", so each block should take 1.8 + 0.75 = 2.55 inches of tape. There are always a few errors, causing the program to Skip-And-Blank-Tape (about 3 inches each), but not enough to skew the calculations. 8500 blocks should take about 1800 feet of tape. Our reels are nominally 2400 feet, and although most are slightly shorter, they're much longer than 1800 feet. Question: Does anybody have an idea why our tapes won't hold more data? Maybe my assumptions are wrong? To Ed Thelen: As you requested before, I will get a program "listing" to you for your records. The program is hand-coded, so it'll be a pseudo-listing, but should be good enough. Best, --Jack Jack Ghiselli, Consultant Email: jghiselli@sbcglobal.net Cell: 1-408-839-1051

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(comment in e-mail from Jack Ghiselli)

I have not changed Ron Williams' original "Wear Out Tapes" program.  
It operates as Ken and Mike describe -- if you punch rewind on one tape front-panel, 
then when the program rotation sequence tries to write on the rewinding drive, 
the program will hang (no other tapes move) until the rewind is complete. 
Then it will resume.

The new "Exercise Tapes, Ron 2.0" operates slightly differently:
   1. It uses Sense Switch G to rewind all tapes.
   2. It checks for end-of-reel.  Today, we found that the reel on CT Tape 2 
         had a reflective spot at the front positioned diagonally 
         so that it was seen by both 
         "beginning of tape" and "end of tape" sensors.  
      The old "Wear Out Tapes" didn't care, and happily wrote past 
         the "beginning/end of tape" reflective spot.  
      The "Ron 2.0" program saw this as a VERY short tape.  
          Allen and I replaced the tape's reflective spot, and it now works OK.
   3. Just for fun, "Ron 2.0" checks for Tape Write Errors.  If a Tape Write fails, 
          it performs the typical error recovery:  
          Backspace, Blank Tape (skip about 3 inches, hopefully over the bad spot), 
          and retry the Write.  
       When this happens, you see a brief "quiver" of the tape.  
       However, on DE Tape 2, the reel is apparently VERY dirty or creased 
          towards the front, so I saw that tape try over and over (about 30 seconds) 
          until it eventually found a good spot.  
       The optional print statistics (SS F) will show how many errors actually occur.

Jack Ghiselli, Consultant
Email:  jghiselli@sbcglobal.net
Cell:  1-408-839-1051


Mike Albaugh also commented ...

You are intended to start the high speed rewind by turning on Sense Switch G. 
   This will rewind all (active) drives.

By manually initiating the rewind on one drive, 
    you effectively took that drive out of service, 
    so when the program got to it in rotation, 
    it stalled on an attempt to read an out-of-service drive.

It would probably work to disable the drive you are about to manually rewind 
   (Sense Switches B,C,D,E for drives 1,2,3,4), 
   then walk over to the drive and manually rewind, 
   but if you are standing at the Sense Switches already, why bother?

-Mike

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OPERATING INSTRUCTIONS: "Exercise Tapes, Ron 2.0"
program for the 1401 (Revised 2019-05-20 JG)

1. The "Exercise Tapes, Ron 2.0" program will exercise from 1 to 4 tapes simultaneously. This program is an alternative to demonstrating the tapes by running them from the TAU panel inside the 1401. This program is an update to Ron Williams' original "Wear Out Tapes" program, adding checks for end-of-reel (so the tapes don't run off the reel), and adding optional printing of statistics.

2. Make sure the tape drives you want are loaded and ready. Be sure all reels have write-protect rings in (Tape Drive front-panel "WRITE PROTECT" lamp should be off). On the tape drives, be sure the tape drive select numbers are set to "1", "2", "3" and/or "4". (When you run from the TAU panel, you usually set them all to "1"). Don't set any two drives to the same number.

3. Be sure the Tape Select dial on the 1401 front panel is set to "N". This dial is just below the RUN/ALTER/etc. dial on the front panel. (When you run from the TAU panel, you usually set this to "1")

4. Load the "Exercise Tapes, Ron 2.0" program deck on the 1402 Card Reader.

   1. Don't panic that not too much happens at first. The program halts, with the 1401 front panel red STOP button on (Program Halt). This is to allow you to fool with Sense Switches, to control program operation

   2. Set the 1401 Sense Switches to control operation:
      1. Sense Switch A is not used by the program. It is recommended that you leave Sense Switch A on (up) for normal Last-Card-in-1402-Reader for other programs.

      2. Turn Sense Switch B on (up) to use Tape 1. Off (down) to ignore this tape.

      3. Turn Sense Switch C on (up) to use Tape 2. Off (down) to ignore this tape.

      4. Turn Sense Switch D on (up) to use Tape 3. Off (down) to ignore this tape.

      5. Turn Sense Switch E on (up) to use Tape 4. Off (down) to ignore this tape.

      6. Turn Sense Switch F on (up) to print optional statistics (and be sure to ready the 1403 Printer). If SS F is on, at end-of-reel the program prints for each tape how many records were written and how many write errors occurred. Turn SS F off (down) to disable printing statistics. Since each record is 1000 bytes long, the record count shows how much data actually fits on the tape. The write-error count shows how dirty our tapes actually are.
         When a write error occurs, the program uses typical error recovery (backspace, skip and blank tape, write again) to bypass the bad spot.

      7. Turn Sense Switch G off (down). During operation, you can turn Sense Switch G on (up) to cause an early end-of-reel. All the tapes rewind, and the program returns to the original HALT. You can change Sense Switch options and press START on the 1401 front panel to resume operations.

5. On the 1401 front panel, press the green START button to begin operation. The tapes you have selected should begin to spin.

   1. The program writes ten (10) one thousand (1000) character blocks to the first tape, then the next tape, etc.

   2. When any tape senses the end-of-reel reflective spot, the program writes an end-of-data Tape Mark on all the tapes, all the tapes rewind, and the program begins another cycle, without halting. Since these tapes have end-of-tape marks, they could be read back by later programs.

6. At any time, you can press the STOP button on the 1401 front panel to pause program operation. Press START on the 1401 front panel to resume operation. For example you might do this if you want to leave the tapes part way down the reel and restart later during the demo. Or, you could run other programs, and then reload the "Exercise Tapes, Ron 2.0" again later to begin from mid-tape.

7. NOISE: You might find yourself pressing the green START button on the 1401 front panel when using this program. This may also start the noisy 1402 Card Reader motor going again. You can stop the motor by briefly opening the 1402 reader gate, or tapping one of the 1402 Stacker Full sensors.

8. After you're finished with "Exercise Tapes, Ron 2.0", be sure to turn on Sense Switch A for normal operations ("Last Card" on the 1402 Reader). If you're polite, turn Sense Switches B-G off.