Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!shawnee.cis.ohio-state.edu!tj From: tj@shawnee.cis.ohio-state.edu (Todd R. Johnson) Newsgroups: comp.sys.amiga Subject: Re: Setting up HardFrame and Quantum 40S Message-ID: <60237@tut.cis.ohio-state.edu> Date: 11 Sep 89 20:50:57 GMT References: <2038@se-sd.NCR.COM> Sender: news@tut.cis.ohio-state.edu Reply-To: Todd R. Johnson Distribution: na Organization: The Ohio State University Dept of Computer & Information Lines: 122 In article <2038@se-sd.NCR.COM> ewing@se-sd.sandiego.ncr.com (David Ewing (AEP)) writes: < I have some questions about setting up my Quantum 40s hard disk < with the Microbotics HardFrame using the HardFrame's RDPrep < program. < With the MB documentation (or lack) its no wonder you have questions. < I want to have two partitions, but all of the defaults in RDPrep < assume you are only going to have one partition. I decided to < make my partition at the point where the sectors/track density < changes, as recommended. < If you are on BIX, you can download a beta RDPrep that is supposed to be better than the old version. < --> Cylinders 0 to 589 contain 35 sectors per track, 105 < physical sectors available. < < --> Cylinders 590 to 833 contain 26 sectors per track, 84 < physical sectors available. < This will not work for several reasons. First, MB is wrong about the number of sectors per track from 590 - 833. It is actually 28, not 26. 3 heads * 26 sectors/track = 78 sectors per cylinder. However, you actually have 3 heads * 28 sec/track = 84 sec/cyl. Second, 590 * 105 + 244 * 84 = 82,446 total sectors. However, one sector for every 6 tracks is used for default management, so you can't use all 82,446 sectors for data. 82,446 - 417 (for default management) leaves 82,029 usable sectors. Third, your mountlist entries can't use all of these sectors because the first part of the drive must be set up as the Rigid Disk Block. Usually the first cylinder is used for this. Fourth, if you set up two mountlist entries with the second having a smaller number of sectors per track than the first, you will actually end up with overlapping partitions. This occurs because each entry is used to compute a sector number without respect to other entries. AmigaDos then uses this sector number to access the disk. If you were to create the mountlist entries you suggest above, the first partition would end at sector number 590*105 - 1 = 61,949, but the second partition would start at sector number 590*84 = 49,560 and end at 834*84 - 1 = 70,056. Because the second Mountlist entry has 28 sectors per track, AmigaDos assumes that the first 590 sectors also have 28 sectors per track when it calculates sector numbers for the second partition. To overcome this you need to calculate the logical number of cylinders, heads, and sectors per track that will result in the total number of usable sectors. Then you use these numbers to make your mountlist entries. It doesn't matter if the numbers don't actually correspond to the physical construction of your drive, because they are only going to be used by AmigaDos to compute sector numbers. For a 40S use these numbers: 737 cylinders, 3 heads (surfaces), 37 sectors per track 737*3*37 = 82,029 the total number of usable sectors. If you these numbers to set up your two entries (remembering that the first cylinder will be used for the RDB), you will be able to describe the partitions as if they have identical numbers of sectors per track. Thus, AmigaDos will correctly compute sector numbers that don't overlap. Note, that you don't have to worry about actually making the partitions where the density changes. AmigaDos doesn't care what the disk actually looks like, it just needs to be able to compute sector numbers that don't overlap. < My questions are: < < Do you need to (can you) set up a Rigid Disk Block for each partition ? Just one for the entire disk. < If no, how does the controller know that the second partition < has a different number of sectors/track ? It doesn't. < Apparently, the recommended default for the Quantum is 32 sectors < per track. Is this just a compromise between the two values < (35 and 26) ? Yes, and not a very good one. 32*3*844 = 81,024 sectors. You lose 1005 sectors. I beleive that the beta RDPrep will actually compute numbers similar to the ones I've suggested above. < What is "logical blocks per track" (asked for each partition) and < why is the default 98 ? Not sure about this one. < I assume it is desirable to set up both partitions with the Fast < File System. Is this correct ? Unless you crave a slow HD. With 1.3 roms and the HF you don't need to use an OFS partition. < What exactly do I need to add to Startup-Sequence (I am booting < from the hard disk). It says SETPATH must be the first command. < What is the exact command in its entirety ? Setpath or setpatch? All I did was change various floppy assigns to put to HD directories. < Could some kind person send me answers to these questions and any other < pertinent information that I might need to know. < < Note: I have a stock Amiga 2000 (1 megabyte of RAM). < < Thanks in advance, < < Dave Ewing < ewing@se-sd.sandiego.ncr.com ---Todd -=- ---Todd tj@cis.ohio-state.edu