Acceptable in the 80s
Bridge six generations of hardware with a cable
Finding a solution for transferring files to (and I suppose, theoretically, from) the Mac SE is important for more than just Lode Runner.
At the moment, the floppy disk drive is this computer’s only connection to the outside world and it is just too temperamental to rely on. Eventually, I might set up a working AppleTalk network that lets me connect this Mac to my broadband router. But even then what sites am I going to connect to? Even the Lynx, text-only, web browser requires Mac OS System 7 – I’m running System 6. I’m not about to start Telnetting into a remote server running a Unix version of Lynx, just so I can FTP the files from there back to my Mac.
But I do remember that in the 1980s, we used to have a program called LapLink to transfer files between PCs over a serial cable. Is there something like this for the Mac? After a trawl through the dustier corners of eBay, it turns out the answer is ‘sort of’. For £8, I manage to snag a boxed copy of MacLinkPlus, by DataViz, together with the original cable. This was designed to allow data files to be transferred between Macs and PCs. The pictures on the eBay listing include a shot of the first page of the hefty, spiralbound manual and this shows a copyright date of 1986 so there’s a good chance it will work on my SE.
Original floppies
The package arrives in great condition. The manual has the original plastic pouches containing the software diskettes (3.5-inch for the Mac software, and both 3.5-inch and 5.25-inch diskette for the PC). There’s a quick-start card explaining how to connect the cable to a PC, a Sun workstation or a NeXT machine. And then there’s the cable itself. This is eight feet long, with an Apple Desktop Bus (ADB) connector at one end and a 25-pin serial connector at the other.
As if anticipating my first objection (who still uses 25-pin serial?), DataViz helpfully included a 25-pin-to-9-pin serial adaptor as well. Unfortunately, DataViz didn’t anticipate my second objection, because I don’t own any PCs old enough to still have a serial port of
I don’t own any PCs old enough to still have a serial port. And I own a lot of junk
any sort. And I own a lot of junk. Off to Amazon then, for a USB-to-serial adaptor (£8.59) to complete the last link in the chain.
Next, the software. I hold my breath and pray to the gods of unreliable floppy drives as the Mac diskette copies across to the SE’s hard disk. They smile down on me. Then I install the PC software on an old Windows laptop and light a candle to the gods of application compatibility, as I run the executable. This time I am sent a plague of boils. This is my oldest PC and it runs Windows 7, 64-bit; I don’t have any PCs running a 32-bit OS anymore. This is a problem because MacLinkPlus was written for the old DOS operating system, which is actually 16-bit. Microsoft dropped support for 16-bit apps across all their 64-bit operating systems, right back to Windows 7.
To get around this, I’ll need yet another intermediary between me and the Mac, this time in the form of a virtual DOS emulator. I start with vDOS, which is a very friendly, simple, and free app. But it doesn’t include serial port emulation, except for printers. DOSBox (dosbox.com) needs a bit more rolling up of the sleeves to set up, but it does at least recognise the adaptor cable. Even better, there is an OS X version. So now I can factor out the PC from this equation altogether!
Any serial port in a storm
Back to the hardware, and the next challenge: to persuade OS X to recognise the USB serial port adaptor. Since El Capitan, OS X has a feature called System Integrity Protection that blocks third party drivers from modifying the kernel. The drivers that ship with the serial port adaptor fall foul of this and so I waste half an hour rebooting into Recovery Mode and using Terminal to disable csrutil, which ought to fix it, but doesn’t. Eventually, I find another set of drivers for the same chipset as the one in my adaptor (bit.ly/silabs_driver_zip). These have been ratified by Apple, so they will install correctly
in Sierra. I can verify this by typing ls /dev/tty.
usbserial in Terminal. It doesn’t say ‘No such file or directory’, so the port is now recognised.
Testing, testing
Time to test my connection! I run MacLinkPlus on both the Mac SE and in DOSBox on my Mac mini (see the ‘How To…’ above). At the default communication speed of 9600 baud (about 75kbps) the connection hangs after 10 or 20 seconds – probably due to electrical noise from all the different adaptor plugs chained together, but dropping to 4800 baud seems stable. There’s also an annoying quirk where closing the connection from the DOS end of the link first will cause the Mac SE to lock up for about 30 seconds, whereas closing it from the other end requires me to reboot my Mac mini entirely. But after I have ironed out these kinks, I manage to successfully transfer some sample text files. And there is much rejoicing.
The final hurdle
But of course, it was never going to be that simple. MacLinkPlus automatically converts data files from most of the common formats, but application files are left as binary files. I can download a disk image of Lode Runner from macintoshrepository.org, but whether I transfer it as an ISO, DMG or BIN file; it doesn’t make any difference. The Mac SE has no way to mount it, without Disk Copy, which wasn’t included by default until System 7. I could download and transfer Disk Copy of course, but I’d still need some way to extract and mount that before I could use it to mount anything else. Even the tantalisingly named Self Extracting Archive (SEA) file format doesn’t work on the Mac SE.
So the bottom line is that I still don’t have Lode Runner on my beloved SE. But I’m trying not to be too downcast about it. Being able to transfer files of any description is a big step forward. One day I’ll get to the end of this rainbow.