From: B. Degnan (billdeg_at_degnanco.com)
Date: 2006-07-03 15:18:24
Ethan, Thanks for answering my questions. I realize that a lot of this stuff had been the subject of posts years ago, but for me it's new ground and I appreciate you're passing along your knowledge. The miniscribe 3650 described in this thread _does_ blink an error after attempting to format for a 1/2 hour or so. I was able to reproduce this effect again by attempting to format the same drive in an IBM XT last night. My D9090 does not have the J14 2 pin jumper, it's a soldered wire. I also tested my ST-225 - It's bad. I do not have any other 6 head drives on hand that are not already committed to another system, I will attempt to get one and let you all know how it goes. If I can't get an ST 251 or Tandon 603s to work, I will make the "snip" and go with the sure thing. Bill At 02:50 PM 7/3/2006 +1200, you wrote: >On 7/3/06, B. Degnan <email@example.com> wrote: >>I just opened up the drive and found J14. As I was about to cut J14 I >>decided that I am ready yet to make this change ... I would rather try to >>find a 6 head drive first. I am patient and I would like to get the full >>7.5 MB's if I can. I am not 100% sure that my ST-225 works, and then I >>would have circumcised the drive controller for no reason. :-) > >On my boards, at least, there's a 2-pin jumper - you can install it or >remove it as you wish. Unlike the metaphor you describe, you _can_ >"uncircumcise" a D9060. > >>A while back I tried using a Miniscribe 3650 that I was given from a >>reliable source, who described it as working. I read someplace that this >>drive was used to replace a tandon 603s successfully. This drive has 6 >>heads and 809 cylinders. > >There's more to it than that... ST506 and ST412 interface drives hace >parameters like at what cylinder to reduce the write current to >prevent bleed-over and a timing thing called "write precompensation". >You have to ensure that the replacement mechanism performs the same >over the cylinders in use as a TM602S and TM603S. I don't have the >relevant parameters memorized, but they can be found in tables of >ancient drives. We all used to have to worry about all these numbers, >if the OS or the controller could be set to honor them, etc. > >A Miniscribe 3650 _may_ be a match, but I have no experience with it. >The ST-225 _is_ a match and that's handy because Seagate made many >millions of them. > >>When I format it starts out OK (you can hear the >>click click click for about a 1/2 hour, and then it just spins with no >>further format activity. I am aware that it can take quite a while to >>format a d9090 drive, but after 5 hours I pulled the plug. > >There are two different formatting times, depending on exactly which >ROM revision you have in your D9090. I found an application note and >posted it once. It describes that with a later version, the format >does indeed take hours and hours (3 for a D9060?), but IIRC, you >_should_ hear it ticking nearly all the time. > >>Perhaps the drive had a defect. > >Perhaps, but I'd expect it to halt and flash the LEDs, not fail silently. > >>Is there a header command that stops the formatting >>process at a pre-defined number of cylinders? > >The normal "N0:..." command does a low-level format, and the number of >cylinders is fixed in the ROMs (the D602S and D603S have the same >number of cylinders, but with 4 and 6 heads respectively). That's why >you get 5MB out of a ~21MB ST225 - it ignores 75% of the drive. > >>Do I understand correctly that the ST-225 is a straight substitute for the >>Tandon 602s D9060 "out of the box", and that no drive controller changes >>are needed? > >That's my understanding from working with various folks 7 years ago on this. > >>I will see if I can dig up a working 6-head ST 251. I may also be able to >>get a Tandon TM603SE. > >OK. > >>One last question...I use this command to check the drive >> >>?ds$ >> >>I get the response code 73 and the DOS version. Is there anything else I >>can do to make sure that the controllers are working? Maybe I have been >>barking up the wrong tree. > >If you get a message then the DOS board can at least talk IEEE. No >guarantees about the SASI-processor on the board or the SASI<->ST506 >bridge board. Without a formatted HDA, I don't know that you'd be >able to prove the bridge card works. > >-ethan > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list
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