Macintosh 68K Machines

Last Update: 2/04/05

I've recently boosted the body count in my computer museum by 3 Classic Macs and some associated hardware bringing my total of 68K machines to around 10. That's at least 9 more than any sane person needs, but they are inexpensive, readily available, and I just can't help myself when I see one. I think it must be because in my mis-spent youth I coveted one, but couldn't afford it.

Initially I acquired one original Mac and a couple Mac Plus systems, but these didn't have internal hard drives nor a PC compatible 3.5" floppy so it is difficult to get new software onto them. Given how inexpensive the later models have become (watch your nearest dumpster) I'd recommend you resist these, however they do mark the start of a great line! There are good reviews of the various models specifications at Low End Mac and Jag's House. If you are thinking of getting one of these I'd recommend you go with the later models which featured the floppy 'SuperDrive' (compatible with PC's 1.4Mb disks), 16 MHz clock rate, and internal hard drives. However you might check out Low End Mac's Road Apple awards as the Classic II and Color Classic are limited by their 16 bit data bus. As a rule I've tried to stay with the 'fish tank' form factor but have a couple with detached monitors. All my Macs use the Motorola 68000 series CPU which seems to restrict me to OS 7.5 or below. Given my usage a nice lean OS 6.0.8 normally does everything I want. The brief link list below will get you started on the extensive information that has been published on the Web if you are interested.

• WWW.info.apple.com/support/ older software
• Low End Mac especially the Early Mac area
• Jag's House can't go wrong visiting here for Mac information
• Lots of detailed Mac external connection interface information
• Mac Drive Museum lot of the older drives available
• System 6 Heaven info and download specific to system 6
• Gamba's description of boot disks, with downloadable archives
• Mac Software archive
• Pickle's Low-End Mac FAQ
• Classic Mac FAQ
• Mac Tech has archives of most of their old articles

I do not have a lot of original content to add, but as usual I did get interested in getting them to talk to the other systems in my collection. Since the early days Linux has supported AppleTalk however there are serial cabling issues, discussed below, that make this a bit messy with most PCs. However I've been very happy using a local ethernet to share data between my Mac's, Linux, and WinDoze. I have several external Asante EN/SC ethernet devices which connect to the Mac via the SCSI port and allow pretty direct communication between all my systems. Between Linux and the Mac I can use ethertalk to set up file shares. Linux also supports the HFS file system through a loadable kernel module and the HFS Utils package. This allows me to create and update Zip disks on a linux box and read them with an external scsi zip drive connected to a Mac. This is my method of choice, but for Mac's equipped with the SuperDrive I can also read and write floppies on the linux box. Although I haven't used it I believe there is a Mac Utility to directly read MSDOS formated 1.4 Mb floppies with a SuperDrive. If I need to communicate with a Windoze system I normally use my local ethernet. There is an NCSA Telnet distribution for the 68K Macs which will run in an FTP server mode. I put this up on the Mac and run WS_FTP from the PC to transfer files. This FTP interface also works with Linux, I just find the file shares a little more convenient. Recently I discovered there are ports of the Unix HFS Utils to both DOS and Windoze, but I've yet to actually try them out.

Now that I have enough Mac's that I can have one in every room I've been looking for some way to justify the collection. I have read about making them into large face clocks, an interesting concept but this doesn't strike me as being particuarly energy efficient. Neither is running a PDP-11 but since I'm likely to do that anyway it seemed the Macs might make pretty nice smart terminals. I found a couple Mac 68K compatible terminal programs at the sites above that included VT100 emulation. So the question boiled down to whether I could connect the Mac's RS422 serial line to the RS232 terminal connection available on most of my PDP-11's without cooking anything. Lots of people sell converters which do this safely, but they are currently selling for around $50 each which I find a little prohibitive (I could have two Mac's shipped for that kind of money!). After a day of searching the net and posting on info-pdp11.org I find that all I need to do is a little bit of creative soldering to create a mini Din 8 pin to DB25 RS232 cable (see link below for pinouts). So far I've only found one commercial source at a small Ebay store. If you have another source I'd love to hear about it.

• Good Cable description covers pin interconnections required for RS232
• Similar to above but includes diagram of Mac mini 8pin connector
• Serial connector voltage specs, with link to original Apple documentation
• Good overview includes interconnection table and pinous for
  various connectors (note MD8 pin 8 should be labeled Rx+)