General Category > Lisa Troubleshooting and Repair

Sun20 Questions/Revival

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sigma7:

--- Quote from: shatle on February 17, 2023, 05:01:24 pm ---I was connecting it to the internal Widget connector. Would it be worth connecting it to a parallel card in the card cage to see if that makes a difference?

--- End quote ---
It is unlikely that a different parallel port will make a difference, although it would be a way to try a different signal path than the chassis cabling.

Note that most operating environments don't treat the parallel card drives the same as drives connected to the built-in parallel port. eg. a drive that is bootable from the built-in port is not bootable from the parallel card in most cases. Notable exceptions are MacWorks Plus II and BLU which do support moving a drive to a different port.

--- Quote ---At the least I can connect to the serial port and see what I can see.

--- End quote ---
Warning: I believe the controller's port is TTL, so you shouldn't connect it directly to an RS-232 port (which has bigger and bipolar voltage signals, and are not compatible with/may damage TTL level inputs)

You can get a few TTL to RS223 converters on Amazon for under $10

sigma7:

--- Quote from: sigma7 on February 17, 2023, 03:46:07 pm ---There was a trick to the low level format which involved subtracting 2 from something. eg. when the formatter asks for the number of cylinders or the last cylinder, you subtract 2 from the actual number. I'm sure I'm not imagining the -2 aspect, but I don't recall exactly what it applies to... I think it is number of cylinders or total number of sectors or something like that.

--- End quote ---
Found some notes...

Helmut Post in Germany was working on figuring out the Sun20 LLF procedure (ca. 2005 I think); I haven't seen a posting from him in a while, so he may not be fiddling with Lisas any more. I'm confident he would have figured it out... maybe one of the other folk in Germany know the details.

Commands for the controller board per Helmut:
>        "F"       Format
>        "BI"     Burn In - - Ten hour test. "Format Media" is test one  ? ?
>        "V"      Verify
>        "D"      Diagnosis
>        "DR"    Dump Register

In a later email, I found "In the meantime, you might see if the "F!" command is useful." Which suggests to me that "F!" is a useful variant of the formatting command. (eg. perhaps the single character "F" command doesn't actually work?)

The following questions are asked for in their formatting program (per Helmut or Larry Parks, not sure):

>> a).  Last Cylinder Number:
>> b).  Number of Heads:
>> c).  Number of Sectors:
>> d).  Pre-Compensation Cylinder:         
>> e).  LUN Status Byte:
>> f).  Flag Byte:
>> g). Interleave Number:

I believe:
- the last cylinder Number is the value that should be entered 2 less than one would expect.
- values are entered in hex
- LUN and Flag bytes should be 0

In a thread regarding the Sun40, I found this:

--- Quote ---Mystery solved. I find that:

The drive formatter in 1.0.18 supports a maximum of 32 MB, while in 1.1h (and MW+II) it is 2 GB.

As long as you _format_ the drive while running 1.1h or MW+II, you can use more than 32 MB, even if you install 1.0.18 on it.

If you format a drive > 32 MB while running 1.0.18, you will probably have I/O errors when using the drive, but these will only occur when reading a sector that has not been written to, so the error may take a long time to appear.

--- End quote ---


--- Quote ---... the Sun20s were notorious for not showing up. I don't know if this was drive specific, or MW+ version specific or what. If you can't get it to appear in Expert mode, restart and try again.

Long ago I heard from a reliable source that you should not power up a Sun20 without the data cable attached to the Lisa. In some cases this screwed up the formatting and the drive had to be sent back to SR to be fixed. I don't know if whatever caused this problem may influence what you are doing {attempting to LLF the Sun20}, but you may want to try both powering-down and not-powering-down the drive when switching from  formatting to the installer.

--- End quote ---

I'll update this post if I find more

patrick:
Years ago I had two of these drives, but never got them to work. I started disassembling the firmware then to better understand how the serial commands work. Perhaps someone would like to complete this now that the official source code is available.

IIRC the formatting routine crashed somewhere during the installation process. Maybe this was related to the "-2" issue -- I always entered the true drive parameters.


The controller board should work with any MFM or RLL drive. If the drive mechanism has more heads or cylinders than supported by the controller, just enter a lower number. The remaining part will remain unused.

shatle:
This project is on the back burner for now, but will update here once I (ever) get the thing back on the bench!

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