Apple Macintosh Classic II

Model M4150 (for UK), 4MB RAM, 80MB SCSI HDD. System Software B1-7.0.1. It was used as a word processor primarily around 1995.

ToDo

try out PPP, SCSI, Ethernet
find a toolchain
MacTerminal and mactar

Repairs

floppy drive eject mechanism has been cleaned and oiled;
CMOS battery has been replaced;
CRT has been adjusted to fill the screen;
unclogged and refilled printer cartrige.

Interoperability

Macintosh relies on multi-stream files on filesystem, which makes file exchange a little cumbersome. It's best to keep files either in text, .hqx or Apple Double, binary representation.

What works:

1.4M floppy drives are readable with an USB FDD on linux, and contain hfs filesystem;
unar can handle both .hqx and .sit to peek into its content, and extracting streams as separate files;
Disk Copy is a must;
StuffIt Expander 4 for System 7 unpacks .sit.hqx;
The Unarchiver for Mac OS X opens .sit just fine;
ShrinkWrap™ 2.0 can mount some images, like .img (same way as .dmg are mounted on modern Mac OS X);
Simple Text for most of the needs;

What's somewhat works:

Compact Pro 1.51 can handle packing large archives (10Mb, 600 small files), however there are no modern unpackers;
small ZIP archives can be created with ZipIt 1.3.8;
fondu can create AppleDouble binary files from resources;

What didn't work:

can't reliably handle 800K floppies;

Connectivity

RS-232 is known to be more error-prone than RS-422, even on short distance. USB RS-232 is readily available, so the only trick is a short and shielded serial cable.

ZTerm 1.0.1 works just fine, note that it configured for software flow control instead of hardware one that used in linux by default;
to setup terminal, run agetty --local-line -hm 57600 ttyUSB0 vt100;
rzsz gives ability to exchange files over serial connection;

Networking

For System 7, MacTCP 2.0.x and MacPPP 2.0.1 are known to work. I found a few resouces: