I’ve had a spate of flakey hardware The API for plugins is well documented and
recently. A wire-wrap board that only works when included with the source code. With it you can write
it’s flexed, an SE/30 that randomly refuses to boot, emulators for additional I/O devices or even create
and an Apple IIgs that only occasionally recognizes new devices of your own. The simulator is also well
its hard drive have all prompted me to take a closer suited for development. I hear PDP- 8 development
look at emulation. Space, too, has played a role. isn’t quite the burgeoning industry it used to be, but
While classic computers overflow the garage, the its educational value remains. Each device (plugin)
emulators merely occupy a directory on my hard has a window displaying its internal state. Through
drive. The manuals and disks for them, instead of the PDP-8/E CPU window, it is possible to view and
filling shelves, reside in PDFs and disk images. edit each register and the contents of memory. The
Thanks to Mini vMac, my Mac Plus rarely comes CPU supports breakpoints, a trace mode, and many
off the shelf. I no longer worry about wear and tear other features you’d expect to find in an advanced
on 20-year-old floppy disks. They’ve been imaged simulator. The front panel plugin is fully functional,
to my PowerBook and safely locked away. The so if you prefer the classic switches-and-lights view,
emulator makes it possible to quickly inspect old it is entirely possible to edit memory, load programs,
programs for my website, without the painstaking and single-step the processor using it.
task of physically transferring them from a Power-
Book G4 to a Mac Plus. “PDP-8/E Simulator does a fantastic
All of my classic Mac games are now just a few job of bringing the PDP- 8 to life on
clicks away, but as anybody knows, playing in an your desktop, offering more func-
emulator just isn’t the same as having the real tionality than the original.”
thing. Granted, it’s much more convenient when
there’s serious work to be done, but for just playing In fact, Baehr’s website contains a tutorial
around, the hardware is half the fun. There are some explaining how to operate a PDP- 8 with no system
systems, though, where the hardware is either too software, by using the front panel. The process
expensive or too large to make ownership practical. involves toggling in an 18-line program for reading
The DEC PDP- 8, a classic mini-computer from the paper tape (a paper tape reader and punch is built
60s and 70s, is a good example. Simply finding a into the ASR 33 Teletype you have attached). This
PDP- 8 is a significant undertaking, let alone amassing program is then used to load a more sophisticated
the necessary peripherals (paper tape reader, RK05 paper tape reader, which you can finally use to load
disks, etc.) and getting them all running. your own program.
PDP-8/E Simulator, by Bernhard Baehr, does a For more sophisticated use, attach an RK8-E Disk fantastic job of bringing the PDP- 8 to life on your System, and you can run Focal- 8, OS/8, Pascal-S, desktop, offering more functionality than the and ETOS. Mount the RK05 DECpack that contains original. While the 8/E has 4K words of memory your desired system, toggle in the RK8-E boot code, by default, the simulator comes with a plugin for and run. OS/8 was the most common operating a KM8-E Memory Extension, bringing the memory system for the PDP- 8 and is a good place to start. up to 32K words (each word is 12 bits). There Included on the OS/8 DECpack is the classic are additional plugins for an ASR 33 Teletype, text editor TECO, from which Emacs eventually PC8-E High-Speed Paper Tape Reader, RK8-E developed. TECO documents are created by the Disk Cartridge System, LP8-E Line Printer, three OS/8 command “MAKE filename.” For a glimpse different clocks, and a TSC8-75 board (for running at 1970s hacker humor, try entering the command the ETOS time-sharing operating system). There’s “MAKE LOVE.” even a KC8-EA Programmer’s Console (i.e., “front Tom Owad ( owad@applefritter.com) is a Macintosh consultant panel”) so you can toggle switches and watch the in York, Pa., and editor of Applefritter ( applefritter.com). He is blinkenlights. the author of Apple I Replica Creation (Syngress, 2005).
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