napabar, I'm totally lost now. Does Easy Share require AppleShare? And it seems to also require HFS. If that's the case, then no it will not work on a 128K. The 128K will not load the HD20 INIT, nor will it recognize HFS disks. AppleShare will also not run on a 128K as it requires HFS.
However, if you only have 400K drives on your 512K, once you startup from a 400K MFS floppy with the HD20 INIT, you can then switch over to a 400K HFS formatted disk, or use one in an external 400K drive. Theoretically you should be able to switch over to the system on an HFS formatted 400K disk, even though you can't startup from it. Since the HD20 INIT is loaded into RAM, I'm not sure it actually needs to be in the System Folder of your EasyShare disk. EasyShare and AppleShare should then have no problems writing to the HFS formatted 400K disk, assuming they will recognize a 400K volume.
One other note, there are problems with the HD20 INIT code in that it's not completely compatible with some programs because it isn't actually the same as the HFS code in the 128K ROM. Therefore, it may not work with Easy Share. This was a problem with a number of early file sharing systems during the transition to HFS, prior to AppleShare. AppleShare did not arrive until 1987, by which time, it assumed native HFS. This is in part no doubt why the 512K AppleShare client is limited, compared to the Plus and other clients, and cannot be run as an AppleShare server, RAM considerations aside.
However, if you only have 400K drives on your 512K, once you startup from a 400K MFS floppy with the HD20 INIT, you can then switch over to a 400K HFS formatted disk, or use one in an external 400K drive. Theoretically you should be able to switch over to the system on an HFS formatted 400K disk, even though you can't startup from it. Since the HD20 INIT is loaded into RAM, I'm not sure it actually needs to be in the System Folder of your EasyShare disk. EasyShare and AppleShare should then have no problems writing to the HFS formatted 400K disk, assuming they will recognize a 400K volume.
One other note, there are problems with the HD20 INIT code in that it's not completely compatible with some programs because it isn't actually the same as the HFS code in the 128K ROM. Therefore, it may not work with Easy Share. This was a problem with a number of early file sharing systems during the transition to HFS, prior to AppleShare. AppleShare did not arrive until 1987, by which time, it assumed native HFS. This is in part no doubt why the 512K AppleShare client is limited, compared to the Plus and other clients, and cannot be run as an AppleShare server, RAM considerations aside.