ac4@pucc-h (Putnam) (03/15/84)
Here is another variation on half-height drives for your IBM-PC. I bought my PC way back "in the beginning" when all I could get was single-sided drives. I tell people (and try to tell myself) that the best advice in this business is to not buy anything new until you really need it in order to get the most for your money. I really needed more storage, but not really 10Mb. Besides, I was worried about trying to backup a 10Mb hard disk on my single-sided floppies. And I needed something that could read the defacto "standard" DSDD floppies that everyone else seems to have these days. Solution: remove one of the SSDD drives and replace it with two half-height 96-tpi (quad density) double-sided drives. You can buy these drives for just a few bucks more than a "normal" 48-tpi (double density) drive. I bought two TEAC FD-55F half-height drives from MicroXpress for $520. I also bought a power Y-cable ($15) and an external logic cable ($35) which plugs into the disk controller card in back; I routed it back inside to the drives. And of course I needed the device driver software; I bought the Tall Tree Systems JFORMAT package for $35 from MicroXpress. The package includes a disk formatter and a driver. It comes in versions for 1.1 (patches DOS) or 2.0 (loadable device driver through CONFIG.SYS). DOS cannot really use the quad-density drives as "standard IBM" drives unless you fool it by copying the first 40-tracks of a standard DOS diskette onto the first 40 tracks of the normally 80-track diskettes used in the quad drives. Instead of fooling around with that mess, I set my system switches to say I have one "official" drive (A) which is my old standard SSDD drive. I boot from that drive. The CONFIG.SYS for DOS 2.0 is set to load the JFORMAT driver for the quad drives which I can then use as drives C and D. The JFORMAT driver has logic to go out and look at the media descriptor byte on the first diskette sector and figure out what kind of diskette it is. If it is a 48-tpi format, the driver "double steps" so you can read the standard diskettes. You can also write them if you are careful. The key is not to write in 48-tpi format on a diskette that has been used in 96-tpi format unless you first degauss the diskette. This can be accomplished with a bulk tape eraser (available for around $15 from your local Radio Shaft store). If you don't do this, there is "noise" left between the tracks and the 48-tpi drives will detect it and get confused. I have written numerous 48-tpi diskettes and read them on other systems with no trouble. The best part of this whole affair is that I now have 5-1/4" diskettes that can hold over 800,000 K bytes if I use the JFORMAT 10-sector/track mode. By the way, you don't have to buy those expensive diskettes - the DSDD diskettes work fine. I found it useful to patch the driver tables as noted in the JFORMAT manual. This is not something you want to try to tackle if you are a novice. To put it another way, I know a rank novice who actually did this and made it work, but I was able to help him make it work much better by understanding what these patches were doing. The JFORMAT package does include the device driver source, by the way. A note of caution: I have not tried any copy-protected diskettes. I imagine some of the protection schemes bypass the DOS drivers and muck-around on the diskette. So I don't know if I can use, for example, LOTUS 1-2-3. I have been using this system for about a month now without any hardware problems. I am not overly enamored with the TEAC drives. They work fine, but unlike the Tandon drives, they don't leave the head loaded all the time, so you get a "clack" sound every time you spin-up the drive and load the head. They tell me that saves on media (diskette) wear, but I am no expert in such matters. As for MicroXpress as a mail-order supplier, their heart seems to be in the right place, but their execution left something to be desired. My first shipment arrived within a couple of days after my telephone order, but they left out the cables and mounting brackets. The next time around, they sent the wrong mounting brackets. They seem happy enough to correct these problems promptly over the telephone, and I know other people who have done business with them with no trouble. They are located in Anaheim, Calif. (714)632-8512. The best thing I can say is that they had the best prices I could find for these drives. Happy hacking (clacking?) !!! Tom Putnam ...!pur-ee!pucc-h:ac4