Folks, I discovered something new with my SE/30 & FloppyEMU last night. I reported it to Steve Chamberlin of BMOW, and he kindly wrote back with the answer. I thought it might be a situation where some of you vintage Mac hackers might get some kicks out of this.
BACKGROUND
As you know, the SE/30 cannot support the Apple Hard Disk 20 (aka HD20) serial hard drive. The HD20 attaches to the external floppy drive connector on the SE/30. That means even if you set your FloppyEMU to be in HD20 Mode, connecting it to your SE/30 won't work. However, if you have a BMOW ROM-inator II ROM SIMM (or similar ROM SIMM from Kero's Mac Mods, CayMac vintage or Garrett's Workshop), it is programmed with a modified IIsi ROM that enables HD20 Mode on the SE/30! Such a ROM SIMM allows you to use a true HD20 or the FEMU (in HD20 Mode) on the EXTERNAL drive connector.
THE PROBLEM
What I discovered last night is something few people have ever tried. I connected my FEMU (set to HD20 Mode) to the INTERNAL floppy drive connector on my SE/30 motherboard. That's easy to do because the FEMU's ribbon cable has a detachable connector, allowing you to make that connection very easy! Sadly, the FEMU is not detectable at all that way. Neither when booting from ROM or booting from a floppy disk or SCSI drive. That's why I wrote to Steve C. last night.
ROOT CAUSE
Steve told me that the issue is Apple's HD20 INIT code in ROM only supports detection of the HD20 when the HD20 is connected EXTERNALLY.
POSSIBLE TO HACK?
That got me thinking that if the HD20 INIT code could be hacked, maybe the code could be altered to allow a FEMU to be connected to the INTERNAL floppy drive connector and use it as an HD20 Mode drive, which is really neat because you can have drives that are hundreds of Megabytes in size (albeit, running at the speed of a floppy drive). In other words, there seems to be a restriction in place that prevents the HD20 from working when connected to the INTERNAL floppy connector. So a hack to remove that limitation should allow the HD20 to work, right? Or am I missing something?
WHY EVEN TRY?
Hackers don't need a good reason to hack. They just hack. I'm not a hacker, but some of you are. But I actually do have a reason. It's hard to get data onto the SD card of the TashTwenty. It's not as simple as the FloppyEMU or BlueSCSI or MacSD to use a modern Mac to simply drag and drop files to the SD card. It's much more complex. So I was thinking that if I could connect my Tash20 and my FEMU (in HD20 mode) to my SE/30 at the same time, I have a System 3.2 disk image on my FEMU packed with software that I would only need to drag and drop onto the Tash20 drive! Super simple! And in the future, if I wanted to modify that software, I'd do the mod on the FEMU DSK image, then connect both again on my SE/30 and do a file copy in the Finder. But because of the HD20 INIT code limitation, I cannot connect both at the same time. That got me thinking about the reason why, and inspired me to write Steve C., who then replied and inspired me to write this post.
I'm not a 68K programmer, so I don't know if a hack to the HD20 INIT code in the IIsi ROM is even possible, but I just wanted to mention this for those of you who love tinker with code a little different.
BACKGROUND
As you know, the SE/30 cannot support the Apple Hard Disk 20 (aka HD20) serial hard drive. The HD20 attaches to the external floppy drive connector on the SE/30. That means even if you set your FloppyEMU to be in HD20 Mode, connecting it to your SE/30 won't work. However, if you have a BMOW ROM-inator II ROM SIMM (or similar ROM SIMM from Kero's Mac Mods, CayMac vintage or Garrett's Workshop), it is programmed with a modified IIsi ROM that enables HD20 Mode on the SE/30! Such a ROM SIMM allows you to use a true HD20 or the FEMU (in HD20 Mode) on the EXTERNAL drive connector.
THE PROBLEM
What I discovered last night is something few people have ever tried. I connected my FEMU (set to HD20 Mode) to the INTERNAL floppy drive connector on my SE/30 motherboard. That's easy to do because the FEMU's ribbon cable has a detachable connector, allowing you to make that connection very easy! Sadly, the FEMU is not detectable at all that way. Neither when booting from ROM or booting from a floppy disk or SCSI drive. That's why I wrote to Steve C. last night.
ROOT CAUSE
Steve told me that the issue is Apple's HD20 INIT code in ROM only supports detection of the HD20 when the HD20 is connected EXTERNALLY.
POSSIBLE TO HACK?
That got me thinking that if the HD20 INIT code could be hacked, maybe the code could be altered to allow a FEMU to be connected to the INTERNAL floppy drive connector and use it as an HD20 Mode drive, which is really neat because you can have drives that are hundreds of Megabytes in size (albeit, running at the speed of a floppy drive). In other words, there seems to be a restriction in place that prevents the HD20 from working when connected to the INTERNAL floppy connector. So a hack to remove that limitation should allow the HD20 to work, right? Or am I missing something?
WHY EVEN TRY?
Hackers don't need a good reason to hack. They just hack. I'm not a hacker, but some of you are. But I actually do have a reason. It's hard to get data onto the SD card of the TashTwenty. It's not as simple as the FloppyEMU or BlueSCSI or MacSD to use a modern Mac to simply drag and drop files to the SD card. It's much more complex. So I was thinking that if I could connect my Tash20 and my FEMU (in HD20 mode) to my SE/30 at the same time, I have a System 3.2 disk image on my FEMU packed with software that I would only need to drag and drop onto the Tash20 drive! Super simple! And in the future, if I wanted to modify that software, I'd do the mod on the FEMU DSK image, then connect both again on my SE/30 and do a file copy in the Finder. But because of the HD20 INIT code limitation, I cannot connect both at the same time. That got me thinking about the reason why, and inspired me to write Steve C., who then replied and inspired me to write this post.
I'm not a 68K programmer, so I don't know if a hack to the HD20 INIT code in the IIsi ROM is even possible, but I just wanted to mention this for those of you who love tinker with code a little different.