torch@attctc.Dallas.TX.US (Jay Finger) (12/22/89)
About three weeks ago I posted a request for information on building your own hard drive. I said at the time that it would be two weeks before I could post a summary, but, alas, I got busy with other things. I don't know how useful this is with Christmas only three days off (or probably allready overwith by the time most of you read this), but here it is anyhow. Here's the original posting: >I'm about to get a new Mac, and instead of paying somebody to slap a drive >into a case I'd like to do it myself. Can anybody pass on instructions, >hints, warnings, and suggestions on good drives? Don't bother replying >just to tell me to ignore Quantums. Ony four people responded (about 20 asked me to pass along any info I received). Special thanks to: ejd@iris.brown.edu (Ed Devinney) allbery@NCoast.ORG (Brandon S. Allbery) wiseman@TELLABS.COM (Jeff Wiseman) bob@ivucsb.sba.ca.us (Bob Bishop) At the end of this posting is a copy of Apple's Tech Note #159, "Hard Disk Hacking" (from ejd@iris.brown.edu). Apple officially discourages building your own drive, but they're doing on the assumption that you're planning on writing the device driver yourself. Since you can buy this software elsewhere Apple's arguments really become moot. First for the "how-to" information: From allbery@NCoast.ORG (Brandon S. Allbery): >I took a cast-off (Seagate) ST251N [...] and put it into a cheap >PClone-style enclosure. Formatting software from Technology Works ($50), >ditto the 25-to-50 cable ($30), but you should be able to find both >anywhere and might be able to get a better price. It was basically a >simple assembly job, since it was fairly obvious what gets plugged >into what. From wiseman@TELLABS.COM (Jeff Wiseman) >Track down the September 1988 issue of "Computer Shopper". There is an >excellant article that I am sure will give you just what you want. >(there was a companion article to this but I don't remeber if it >preceeded or followed it). It seems that the SCSI Seagate 60M driver >is interchangable with the 40M that Apple uses. By doing a 2 byte change >in Apple's generic driver software (using ResEdit), you can make it >support this (cost effective) larger drive. Now, about which drives are better: I only received two comments about what kind of drive to go with, both of them recommending Quantums. This is probably the route that I'm going to go; I had already decided on that before I received the comments. If I was shopping in the 150 and up range I would get an Imprimis or Maxtor drive. Here is Apple's Tech Note # 159: +++++++++++++++++ reproduced without Apple'spermission, etc ++++++++++++++++ #159: Hard Disk Hacking See also: Technical Note #96 Q SCSI Bugs Technical Note #134QHard Disk Medic The Device Manager Written by: Bo3b Johnson September 1, 1987 Updated: March 1, 1988 ___________________________________________________________________________ For those of a technical bent with some extra time, you can build your own hard disk system from a cheap SCSI drive and a driver that you write. This is not a project for those short on time, so beware. ___________________________________________________________________________ We often get questions regarding the feasibility of connecting a TgenericU SCSI drive to the Macintosh, usually the Macintosh II. It is possible to use a standard drive, but it is important to be aware that there is a reason why a fully assembled drive costs more. When buying a hard disk you have two choices: 1) buy a fully assembled drive, formatting and driver software included 2) buy the pieces necessary to assemble your own: the drive itself, power supply if needed, cables, and development system to write a driver and formatter. The second choice will often appear to be cheaper, since you donUt have to pay for a fancy case with a fancy label. However, you are also missing the chance to pay for some fancy software that took some fancy amounts of time to write. Do not underestimate the difficulty of building your own hard disk. SCSI drives are only partially standardized so a driver written for one drive will probably not work (at least not well) on another drive. All drives come with a formatting utility that also contains a driver for reading and writing sectors to the disk. For example, the Apple drives come with a program called HD SC Setup. Most third-party drives have a similar utility that is specific to their drive. The formatting operation varies widely depending on the drive, and the driver also may have to know about specific timing problems with a given drive. HD SC Setup only supports the drives which we produce. If you decide that you want to hack together your own drive, you will need to write this formatter/driver program. It is non-trivial, and this is part of what you pay for when you buy an off-the-shelf drive. If you have the time, you may save some money. If you are writing your own formatter/driver program we can help you with problems you run into, but you must be familiar with SCSI terminology, the SCSI Manager, and be able to use an assembly level debugger like Macsbug or TMon. You may run into timing difficulties that require the use of a logic analyzer or SCSI analyzer to resolve. This may sound like it is hard to write your own driver. It is. This may sound like we are trying to scare you off from writing your own driver. We are. A ++++++++++++++++++ end of Tech Note ++++++++++++++++++++++ Hope this helps! Jay Finger, {ames,mit-eddie}!attctc!torch ames!torch@attctc