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Author Topic: 800k / DS 3.5 drives and the Lisa 2/5?  (Read 741 times)

compu_85

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800k / DS 3.5 drives and the Lisa 2/5?
« on: March 07, 2021, 03:18:43 pm »

I just picked up a 2/10 which has been XL-ified, including the 800k floppy upgrade.

From what I understand, the only changes required on the 2/10 are the floppy ROM, and the drive itself.

The 2/5 doesn't use an IWM for the floppy drive. Is there a way to install an 800k drive in a 2/5? I assume the ROM is different.

Thanks!
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sigma7

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Re: 800k / DS 3.5 drives and the Lisa 2/5?
« Reply #1 on: March 08, 2021, 08:00:13 pm »

Yes, there is an 800k ROM for the 2/5 I/O Board.

So that makes 5 common I/O Board ROM variants
  • 2/5 - Twiggy
  • 2/5 - 400K
  • 2/5 - 800K
  • 2/10-400K
  • 2/10-800K
The 2/10-800K ROM was not patched correctly when updating from 400K to 800K circa 1988. The consequence is that this ROM will often fail to re-format a floppy that has previously been formatted.

BLU has a "zero disk" function that clears the formatting on a floppy (not just erase the data), after which a 2/10 with this ROM can successfully format it.

Recently, the 2/10-800K error has been located and corrected, and a ROM variant created that is "universal" in that it checks to see if the drive is 400K or 800K (so the ROM does not need to be changed when changing the drive). A similar variant has been made for the 2/5 3.5" drives.

So this adds two more variants that are designated:
  • 25SSDSM6 (2/5 400K & 800K)
  • XLSSDSM6 (2/10 400K & 800K & re-formatting fix)

Finally, there is a dual Twiggy & 3.5" drive ROM for the Sapient Technologies 2/5 I/O Board, which permits changing between Twiggy and 3.5" drive ROMs using a jumper on the board. This is a double-size ROM, so is a 28 pin 2764. The other I/O ROMs are 24 pin 2732s.

Conceivably one could make a dual Twiggy & 3.5" ROM for the 2/10 as the board hardware has provisions for this option, but AFAIK a Twiggy compatible ROM hasn't been made for the 2/10.

edit: the "universal" (400K/800K) variants have been posted in the Files category
« Last Edit: March 09, 2021, 02:08:01 pm by sigma7 »
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compu_85

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Re: 800k / DS 3.5 drives and the Lisa 2/5?
« Reply #2 on: March 08, 2021, 10:04:29 pm »

Thanks for the explanation!
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