d7pernb@hacke0.UUCP (Nicklas Pernblad) (06/25/88)
I recently got a Seagate ST4144R hard disk for my A2090 controller. The hard disk has a MFM formatted capacity of 80MB, but since it has 9 heads and 2090 only can handle 8, the maximum storage you can expect is 71MB. I was able to successfully format all 1024 cylinders and info revealed 69MB free. But after a reboot or loadwb the hard disk would go into an endless validating loop. After prep-ing the drive with decreasing number of cylinders, 777 seemed to be the highest reliable value giving me 52MB. Is this a limit in AmigaDOS, 2090 or in my knowledge? And why a 52MB limit, I could understand 32, 64, 128MB...? A question to some CBM technical expert: The A500/A2000 Technical Reference Manual (page 160) documents a pin on the 2090 called 'Write Protected'. I thought this would be a neat way to keep any virus' greedy hands off my hard disk. But after a few experiments I discovered that the pin does not seem to be used at all. Is this a correct observation? Is there any other way to write protect the hard disk? Nicklas Pernblad
cmcmanis%pepper@Sun.COM (Chuck McManis) (06/28/88)
In article <191@hacke0.UUCP> d7pernb@hacke0.UUCP (Nicklas Pernblad) writes: > ... And why a 52MB limit, I could understand 32, 64, 128MB...? >Nicklas Pernblad Because there isn't an archive bit in the root block. (Finding out why this causes this problem is left as an exercise for the reader, note you will need Kim DeVaughn's file system document and the 1.2 enhancer manual (or autodocs 'cuz the clue is in the readmes too). Suffice it to say that you can have, at most 52 Meg in a partition for 1.2, >52Meg in 1.3 iff you are using the Fast File System for that partition, and >52Meg anywhere in 1.4. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.
lfk@amdahl.uts.amdahl.com (Lynn Kerby) (06/28/88)
In article <191@hacke0.UUCP> d7pernb@hacke0.UUCP (Nicklas Pernblad) writes: >I recently got a Seagate ST4144R hard disk for my A2090 controller. The >hard disk has a MFM formatted capacity of 80MB, but since it has 9 heads >and 2090 only can handle 8, the maximum storage you can expect is 71MB. >I was able to successfully format all 1024 cylinders and info revealed >69MB free. But after a reboot or loadwb the hard disk would go into an >endless validating loop. After prep-ing the drive with decreasing number >of cylinders, 777 seemed to be the highest reliable value giving me 52MB. >Is this a limit in AmigaDOS, 2090 or in my knowledge? And why a 52MB limit, >I could understand 32, 64, 128MB...? > I think that I can answer this one, the limit is in AmigaDOS, it can't handle more than 54MB per partition. I don't know why the number is 54 though. You can partition the drive into multiple segments and you should be able to use the full capacity (less filesystem format info and lost heads). >Nicklas Pernblad -- Lynn Kerby - Amdahl Corporation Sunnyvale, CA ...inhp4!amdahl!lfk Disclaimer: Any and all opinions expressed herein are my own and do not necessarily represent the views of anyone, especially my employer.