Path: utzoo!attcan!uunet!seismo!ukma!tut.cis.ohio-state.edu!ucbvax!pro-graphics.cts.com!bobl From: bobl@pro-graphics.cts.com (System Administrator) Newsgroups: comp.sys.apple Subject: Vanilla HD Construction (Article 2) Message-ID: <8908281945.AA23448@trout.nosc.mil> Date: 26 Aug 89 19:14:34 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 433 BUILDING YOUR OWN SCSI HARD DRIVE By Rick Hannon When I first gave serious thought to building my own hard drive I must admit I had some doubts. Let me rephrase that, many doubts. Letting you in on my experience you will find that its not that difficult and more cost effective than buying an assembled drive. My biggest fear was laying out $750 only to end up with a bunch of used computer parts. This fear stayed with me until the first time I booted up my machine with the hard drive. I was also afraid that during the assembly I would cross a wire or somehow damage the drive leaving me with a repair bill before I even start. As you will soon see, assembly is very easy and can be finished in under an hour. The hard drive assembly I used was a Seagate ST277N which is a 60 megabyte SCSI (Small Computer System Interface) drive. The drive was ordered from Hard Drives International. The external drive case was from Tulin Corp. and included internal cabling and cooling fan. The external cable and power cord were additional and were bought from Tulin also. The Apple SCSI interface was bought from a local Apple dealer. Other drives and cases are available from many sources. Just browse through any issue of "Computer Shopper" to find what is available. Both orders were placed on a Tuesday afternoon and arrived exactly seven days later. The hard disk was very well packed with two-inch thick foam rubber surrounding the drive. The drive is in a sealed plastic bag and placed inside a smaller box. The external case was wrapped in bubble wrap and placed in a box full of styrofoam peanuts. You are bound to be excited to get started but please wait. Ideally you should let your hard drive assembly stay sealed in its plastic wrap for 24 hours to climatize to the environment it will be used in. If you really can't wait that long at least study the manuals included and take a good look at the external case and parts involved. That should take 8 to 12 hours... Right! While we wait for the drive to climatize, lets take a look at the external drive case from Tulin Corp. The case is all metal construction measuring 4 1/4" high, 9 3/4" wide, and 10" deep. The finish is baked enamel in the Apple platinum color. Two drives could easily be installed with just a different internal cable and mounting bracket. The Seagate ST277N needs a 13 watt power supply so the installed power supply is large enough for two drives. Very nicely done construction; however, the power switch is "cheap" and I would prefer a toggle switch similar to the one on the back of my computer. Now that we have read the instruction manuals included and the drive has climatized, lets begin by taking the following precautions: o DO NOT unwrap the drive until you are ready to install it in the system. o Always handle the drive by the frame or casting. o Do not touch the board components or connectors without taking static-discharge precautions. DISK DRIVE ASSEMBLY 1. Remove the three flat head screws from the front panel. Pull the front panel off the case being cautious not to pull any wires that might be connected to the green LED on the panel. If the wires are not already disconnected, do so now. 2. Remove the black plastic switch extender (located on the right over the power switch). 3. Slide the base plate assembly out though the BACK of the case. (You might have to turn the base plate slightly to get past the screw on the inner right side.) 4. The assembly instructions from Tulin showed how to wire the LED to show disk access but with my ST277N I could not do so because the drive didn't have a wire connecting to the LED on the disk drive. Even if the drive had the wire, some soldering would be necessary. Very few should be brave enough to try this. Instead, mine shows power on only. 5. Open the wrapping from the drive assembly and carefully remove. Remove the front black bezel from the drive by removing the two brass screws holding it in place. 6. Locate the SCSI address jumpers on the drive assembly and remove the jumper connected to pins. Attach the small ribbon cable to the address jumpers. The red stripe on the cable should be on your right when looking at the drive from the rear. Do not use pressure. 7. Attach the 50-pin SCSI cable to the drive, again the red stripe should be on the right when looking at the drive from the rear. Be sure it is locked on tight. 8. Carefully place the hard disk onto the base assembly and attach it with the four supplied screws. If you have trouble aligning the drives assembly's holes to the base plate, loosen the power supply's mounting screws to provide some slack. Plug either one of the cables from the power supply to the hard drive's circuit board. 9. Install the base plate/drive assembly into the case. Attach the two thin wires (one colored, one black) from the power supply to the LED on the front panel of the drive. 10. Attach the power cord to the rear of the case and turn on the front panel power switch by sliding it to the right. WARNING - DO NOT TOUCH ANY COMPONENTS WHILE THE DRIVE IS PLUGGED IN!!! If the LED does not glow, turn off the power and reverse the wires on the LED. 11. Re-attach the front panel assembly, being sure to mount the black plastic switch extender properly on the switch. Tighten the three screws until the back plate is in line with the rear edge of the cover. Make sure the switch extender moves freely. o The decal to cover the screws cannot be removed with damaging it. Do not affix until the drive has been formatted and fully tested. 12. Open the top of your computer and install the Apple SCSI Card (should be Revision C EPROM). Any questions should be answered by reading the manual supplied with the Apple SCSI Card. 13. Attach the DB-25 end of the external cable to the connector on the computer and the other end to EITHER connector on the rear of the drive case. Now its fully assembled. That wasn't bad now was it. Now the really time consuming part to the whole process. Formatting and testing the drive. To do my formatting and testing I used two "freeware" programs written by Joe Jaworski. The programs are called "SCSI Hacker" and "DiskTimer GS." These programs are available on AppleLink, Compuserve, and GEnie. The programs come with very good documentation, so I will only briefly cover them. My instructions assume you have an Apple IIgs using GS/OS and the Apple SCSI Card with Revision C EPROM. FORMATTING AND TESTING o Place the SCSI driver from the System Tools disk into your /SYSTEM/DRIVERS folder on your System Disk. 1. Boot up "SCSI Hacker" from your floppy drive. 2. Choose "Low level format" from the main menu. Choose an interleave of five. Be patient, this might take a while. 3. Quit "SCSI Hacker" and now boot up "HDSCPartition" from your "Apple SCSI Card Utilities Disk." It doesn't matter how you set the partitions, as long as you set one for at least 10 megabytes in size. 4. Now format your hard drive with your favorite utility (Finder, Copy II Plus, Cat Doctor, System Utilities). This should only take a few seconds. 5. Put a copy of "DiskTimer GS" on the new volume and launch it from there. Wait until the tests have finished and write the results down. Example: Read = 93 Seek = 77 Adapter Speed = 51 6. Repeat the process again but this time use an interleave of 10 (0A). Write down the test results of using the 10:1 interleave. Continue to increase the interleave by five until you reach 20:1. 7. Compare the results of the read factor. For my drive the best interleave was between 10:1 and 15:1. Example: Interleave: 5(05) 10(0A) 15(0F) Read Timing: 93 61 67 8. Now to pinpoint the best interleave I must begin the format/testing process increasing the interleave factor by one each time. To make a long story a little shorter the best interleave factor was 10:1. You would think your finished formatting now wouldn't you. The rule of thumb is to increase the interleave by two to achieve the best real-life performance. In my case a low-level format of 12:1 is the best to use. This gives me a "benchmark" reading of: Read = 63 Seek= 90 Adapter Speed = 51 All finished! Very easy to do but just a little time consuming to get everything just right. Now we're ready to install and configure software onto the hard drive itself. Take your time! Backup your hard drive. Set-up subdirectories (folders) to organize all your files. Backup your hard drive. If you partition your drive its a good idea to put applications on one and data on the other. Backup your hard drive. It took every free minute of four days to get all my files onto the drive, so be patient, and backup your hard drive. Those of you who haven't already, let me suggest you fork out $40 to get ProSel by Glen Bredon. It gets its name from the PROgram SELector that comes with the package but the utilities included are more than worth the forty dollars. You will wonder how you ever got along without it. Utilities include a file handler, disk repair, disk zapper, file de-fragmenter, file finder, fast disk copier, disk backup/restore and more. For those who have an Apple IIgs, get ProSel 16! Available February 1, 1989 for just $60. You cannot get ProSel or ProSel 16 from your local retailer. Only from Dr. Bredon himself. Send your check to: Glen Bredon 521 State Rd. Princeton, NJ 08540 COST BREAKDOWN Seagate ST277N ...........................$449.00 Tulin Corp. Case w 30w power supply and internal cabling .....................$119.00 Power cable ..............................$ 4.00 External cable ...........................$ 25.00 Apple SCSI Card w Revision C .............$129.00 --------- $726.00 o Shipping/handling, sales tax, and possible COD or credit card surcharges not included. SEAGATE SCSI DRIVE SPECIFICATIONS ST225N ST251N ST277N ------ ------ ------ Formatted Capacity 21.4 42.8 64.9 Number of Disks 2 3 3 Number of Heads 4 6 6 Avg. Access Time(ms) 65 40 40 Avg. Power Consumption 16.8 13 13 Auto Head Park @ Power Down NO YES YES Ballpark Price $299 $395 $449 All three use sputtered, thin film media and should operate at temperatures of 50 to 113 degrees. POSSIBLE MAIL ORDER SUPPLIERS Hard Drives International 1208 E. Broadway Rd. #110 Tempe, AZ 85282 Orders: (800) 234-DISK (602) 784-1038 Customer Service: (800) 541-8387 Order Status: (800) 541-8387 Telex: 405765 Fax: (602) 829-9193 (Hard drives) Tulin Corp. 2393 Qume Drive San Jose, CA 95131 (408) 432-9025 Telex: 499-4365 Fax: (408) 943-0782 (External cases, cables, & complete hard drive kits) IB Computers 1519 S.W. Marlow Portland, OR 97225 (503) 297-8425 (External cases) Lyco Computer (800) 233-8760 (Hard drives) jb Technologies, Inc. 21011 Itasca St. #F Chatsworth, CA 91311 (818) 709-6400 Telex: 678953 Fax: (818) 341-2935 (Hard drives) ComputAbility P.O. Box 17882 Milwaukee, WI 53217 (800) 558-0003 Fax: (414) 357-7814 (Hard drives) CTI Continental Trading, Inc. (800) 284-8494 (Hard drives) I don't claim to be an expert but I'm always willing to help others who wish to try assembling their own hard drive. You may reach me through the following information services. AppleLink: RHannon GEnie: R.HANNON Compuserve: 75530,3136 ============================================================ A D D E N D U M ============================================================ THIS PORTION PRIMARILY CONCERNS USERS OF HARD DRIVES OVER 40-MEGABYTES IN SIZE WHO USE THE GS/OS OPERATING SYSTEM. Interleave ---------- Shortly after uploading this to the information services it was brought to my attention by Bob Consorti and Glen Bredon that DiskTimer GS gave an incorrect "Read" test with GS/OS. Previous operating systems didn't use multiple block reads and DiskTimer GS doesn't test for this improved method. To perform an accurate "Read" test you must copy the system disk files, and several GS specific programs (AppleWorks GS, MultiScribe GS, Paintworks Plus, etc.) to the hard drive instead of DiskTimer GS. Use a stop watch or any watch with a second hand and time cold bootup and launching of the various programs, recording the results as you go along. Repeat the process with different interleave factors until you find the one which gives the best results. You have now found the correct interleave. Volume Partitioning ------------------- There seems to be another problem with volumes over 40-Megabytes in size when using the Advanced Disk Utility (ADU). I'm not an expert and my explanation of the problem may not be totally correct but my instructions to clear-up the problem are. SCSI devices are intelligent devices. When the low-level format takes place the drive assigns all bad blocks to the end of the drive. "Advanced Disk Utility" will allow you to set the partitions over this bad block area. This results in a corrupted volume bit-map. If you don't believe me, set your partitions to use 100% of the drive then use "SCSI Hacker" to test the last partition on the drive. You should get an error #27 (I/O Error) soon as the test starts. To allow for the bad block area, set 1% of the hard drive as unused. On the Seagate ST277N, ADU leaves 512K as unused disk space. On my hard drive the partitions are as follows: /HD1 = 50% /HD2 = 49% Unused = 1% You probably only have about 100K of disk space that is actually bad but one percent is the smallest amount of space ADU will allow you to partition as unused. As a safeguard I would recommend that you again use "SCSI Hacker" to test the final partition again. This time you should not get the I/O error and the program will allow the test to continue. If it doesn't then you have more than 512K of bad blocks. You will then have to leave an additional one percent as usused. If this is a new drive assembly I would also recommend that you get in touch with the firm you bought the drive from and ask for a replacement. This file was updated on February 23, 1989. | ProLine: bobl@pro-graphics InterNet: crash!bobl@pro-graphics.cts.com | CServe: 70347,2344 ARPA/DDN: crash!pro-graphics!bobl@nosc.mil | AppleLink: Graphics3D ___________ ____________ Raven Enterprises - 25 Raven Ave. Piscataway, NJ 08854