cyamamot@aludra.usc.edu (Cliff Yamamoto) (04/12/90)
Greetings! This question has probably appeared before, but I have never heard a realistic answer to it. I was going to get a Perstor 180 controller to run ARRL (31 sec/trk) using a ST4096. I've called Perstor and they say it works but when I asked if they *guarantee* my drive will work, they refused. "We can't guarantee the quality of hard disks put out from manufacturers". Ok made sense. But why do they sell controllers like this in the first place? (QUESTION #1). So I called Seagate to see if they had any qualms about it. The guy said he's heard of people running MFM drives at higher capacity, but Seagate doesn't recommend it (ok.. sounds familiar). I asked what's the difference between MFM and RLL? He tells me just the electronics since data rates and density are different. I ask him about media differences and he says both MFM and RLL use the same type of media nowadays. Well can't the analog portions of the disk electronics be "retuned" to run MFM, RLL, ARLL or ESDI? (QUESTION #2). Well I could have saved about $330 going the Perstor way (180-16FN with ST4096). But since I've not been convinced that ARLL can be *safely* run on a MFM drive, I went out and ordered a WD10007-SE2 with a 1355 Micropolis drive. I'm sure I should be 'more safe' with this ESDI combination. Yet I'm still curious; how does "tuning" the electronics for a particular drive affect the magnetic patterns on the disk? (QUESTION #3). Does the read/write head require more current to generate higher flux? (QUESTION #4). Or is even the physical geometry of the read/write head on a MFM vs. RLL entirely different? (QUESTION #5). Do the amplifiers on the analog board need to be of higher gain for different encoding formats or is just higher bandwidth necessary? (QUESTION #6). This turned out longer than I wanted but I since I shelled out $330 more, I want to feel "justified" that there is some legitimate technical reason why higher capacity drives cost more even though others may be doing the same with their MFM drives (at a greater risk??!?) Please reply via email or post to these newsgroups (I hope others may be interested in this info as well). Clifford Yamamoto - KA6JRG Email: cyamamot@aludra.usc.edu Jet Propulsion Labs cyamamot@devvax.jpl.nasa.gov 4800 Oak Grove Drive cyamamot@jato.jpl.nasa.gov M/S 238-737 cky@hydra.jpl.nasa.gov Pasadena, CA. 91109 (818) 354-1242