ironborn65 Posted December 13, 2020 Report Share Posted December 13, 2020 (edited) hi all, is it possible to replace the ROMs of the Macintosh II with 800k floppy with the version of the one with FDHD? from this 1987-12 - 9779D2C4 - MacII (800k v2).ROM to this 1988-09 - 97221136 - Mac II FDHD & IIx & IIcx.ROM thanks! Edited December 13, 2020 by ironborn65 Quote Link to post Share on other sites
360alaska Posted December 13, 2020 Report Share Posted December 13, 2020 Yep, I actually got a dead IIcx board for the roms and used a FDHD SWIM from a MAC SE with an adapter. Quote Link to post Share on other sites
ironborn65 Posted December 13, 2020 Author Report Share Posted December 13, 2020 so, do I just need to download the ROMs and burn 4 27C512? Quote Link to post Share on other sites
68kMLA Supporter davidg5678 Posted December 13, 2020 68kMLA Supporter Report Share Posted December 13, 2020 I may be wrong here, but I think that there is more to HD floppy support than just ROMs. I think there is a SWIM chip that also is required in addition to ROMS for this to work. I believe that this is how Mac SE floppy upgrades work, at least. Quote Link to post Share on other sites
ironborn65 Posted December 13, 2020 Author Report Share Posted December 13, 2020 in https://everymac.com/systems/apple/mac_ii/specs/mac_ii.html I read "With the FDHD upgrade kit, the system is capable of supporting 68 MB of RAM (1 MB SIMMs in bank A and 16 MB SIMMs in bank B)." I was wondering if a ROM upgrade from the iifx could do the trick, @davidg5678 is saying a SWIM chip is to be replaced as well. Is anyone aware of what the FDHD upgrade kit for Mac II consist of? Quote Link to post Share on other sites
68kMLA Supporter karrots Posted December 14, 2020 68kMLA Supporter Report Share Posted December 14, 2020 Per wikipedia the Mac II shipped with a IWM. Which is how my board is labeled. Pretty sure the get what you want you need to swap the IWM for a SWIM. Quote Link to post Share on other sites
68kMLA Supporter cheesestraws Posted December 14, 2020 68kMLA Supporter Report Share Posted December 14, 2020 On 12/13/2020 at 5:24 AM, ironborn65 said: I was wondering if a ROM upgrade from the iifx could do the trick, @davidg5678 is saying a SWIM chip is to be replaced as well. Upgrading the ROMs will not magically make an FDHD floppy drive work. The IWM or SWIM is the chip that generates the signals that actually control the floppy drive. The IWM cannot drive an FDHD drive. The SWIM is the upgraded version which can. Quote Link to post Share on other sites
ironborn65 Posted December 14, 2020 Author Report Share Posted December 14, 2020 ROM does magic sometimes .... thanks for the reply, I did not know that, I did no find any SWIM chip for sale, is it something that is usually done as an upgrade? Quote Link to post Share on other sites
Franklinstein Posted January 1 Report Share Posted January 1 Back in the day the SWIM chip was available as an upgrade part; I think it's listed by model number in one of Larry Pina's books. The SE could also be upgraded to FDHD in the same manner. Offhand I don't know the various revisions of the SWIM and which were compatible where, but it's possible you could pull a SWIM from a junk board (probably SE FDHD, SE/30, or other member of the II family) and install it in yours. It should be a PLCC-type chip so just make sure the leads are clean after you desolder it (if necessary) and it should drop straight into the socket on the II's logic board. Anyway the official Apple upgrade to a Mac II FDHD was a set of ROMs, a SWIM, and one SuperDrive along with an "FDHD" sticker to put on the case next to the upgraded drive so you could differentiate it at a glance from the remaining 800k drive. Again, the SE FDHD upgrade was basically the same. Quote Link to post Share on other sites
360alaska Posted January 15 Report Share Posted January 15 Here's and Idea f the hack I did: Quote Link to post Share on other sites
tjjq44 Posted February 22 Report Share Posted February 22 A macintosh II is far more valuable when unmodified... Original (non upgraded) mac IIs are more and more scarce these days... Quote Link to post Share on other sites
ironborn65 Posted February 23 Author Report Share Posted February 23 you are right @tjjq44, I was expected to apply an Apple upgrade, but I was wrong. I'll not mangle with my Mac II. Thanks for sharing you POW best PF Quote Link to post Share on other sites
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