Sage II Computer

oblique view of Sage II computer
(click image for larger view)

The Sage II computer was introduced by Sage Technology of Reno, Nevada in 1982. The quick synopsis of the machine is that it contains a 68000 running at 8 MHz and has 512 KB of DRAM. As is obvious from the picture above, it has two integral 5.25" floppies. It had no hard disk (that was left to the Sage IV). External connections included a serial port for communication with a terminal, a serial port for communication to a modem, a parallel port for connection to a printer, and an IEEE 488 port.

There were two versions of the Sage II. The earlier version had full height 5.25" floppies; the later version had half height 5.25" floppies and a corresponding reduction in the height of the box. Another way to distinguish the machines is that the first edition had under bars and over bars on the "II" of "Sage II", while the second didn't have them (see the picture above).

The UCSD p-System

More interesting than the hardware is that the primary operating system used by the Sage II was the UCSD p-System, specifically a multi-user version of p-System IV. The UCSD p-System was an operating system written in Pascal with a lot of standard software for writing/compiling/debugging Pascal programs (compilers for other languages also existed). Eventually UCSD transferred ownership and rights to SofTech, who continued developing it, including the version used by the Sage.

The p-System wasn't a native compiler. The source program was compiled to an abstract stack machine using a pseudo machine language, called p-code. The "p" of "p-System" stands for pseudo. Like Java, the p-code programs were then interpreted by a native machine language program. Although this extra level of interpretation sapped performance, it also meant that the p-System could be (and was) brought up easily on a machine since most of the OS and utility software didn't even need to be compiled -- p-code was transportable across very different machines.

There were four versions of the p-code architecture, and the Sage used the final one, p-System IV. The original p-code architecture could address only 64 KB of RAM. The IV edition was modified to allow up to 64 KB of p-code and 64 KB of data. As the Sage had 512 KB of DRAM, only 128 KB was used by the p-System, leaving 384 KB for running the p-code interpreted and, mostly, a RAM disk.

Reports exist that say the p-code files could be compiled to native code to achieve faster run times for many types of programs.

Other Operating Systems

Although the Sage II was sold with the UCSD p-System as the primary operating system, others were available. One was Digital Research's CP/M 68K. I'm trying to track down information on this. If you have documents or boot disks and are willing to sell/share, I'm interested.

Mr. Marcus Wigan, a long time Sage/Stride user, notes the wide variety of operating systems available for the Sage. Interestingly, the software architecture of the Sage allowed the machine to host multiple simultaneous operating systems; one user could be running Unix and another running p-System UCSD Pascal.

The Machine

Externally, the box is simple, attractively so. The front panel has two half height 5.25" disk drives and a single bi-color LED. This LED is green while the CPU is "thinking," and turns red when it is halted waiting for I/O or hits an unrecoverable error. There are no connections or distractions on the top, bottom, and sides. The rear panel has the power jack, the power switch (lever toggle), and clearly labeled ports IEEE 488, printer, modem, terminal, two dip switches, and a reset switch.

Here is what is inside the box.

My machine is serial #068789. While it originally went for $3600 (in 1982 dollars!), I picked up for $22.50 on EBay. It is one of my better EBay purchases.

Sage IV

The Sage IV came out in 1983, a year later than the Sage II. The Sage IV used the same CPU logic board as the Sage II and added a second board that sat atop the first board and connected via the system bus connectors. This second PCB contained another 512 KB of DRAM, four serial ports for supporting more simultaneous users, and a winchester controller connecting to either a 5 MB or 40 MB hard disk. Of course the box was larger to accommodate the extra hardware.

Stride 440

After Sage became Stride Computer, they introduced a model called the Stride 440; it was an evolution of the Sage IV. The 8 MHz 68000 was replaced with a 10 MHz 68010, and much more DRAM (e.g. 8 MB) was on hand. This extra power was not of much use for people who used the UCSD p-System OS since individual users were still limited to 64 KB code and 64 KB data. Apparently most users of this machine switched to using A Unix variant or even CP/M-68K.

Documents

Sadly, my Sage II didn't come with any manuals. However, through the power of the internet, a couple people have contributed to make the following documents available. Jerry Wright scanned part of the Getting Started manual. The other manuals here came from David Erhart, who the me manuals for scanning.

The size of the documents normalized by the number of pages varies widely, in part that some manuals are simple bitonal images and others have a large fraction of their content consisting of text over very high frequency colored backgrounds that Acrobat decided to encode with jpeg. With some work to de-screen the jpgs the files could have been made smaller; alas, it wasn't done.

If you have any documentation on this system, please contact me, and perhaps we can arrange some sale or trade to make it worth your time to sell/copy/scan the documents for me.

Monitor ROM

The machine has an 8 KB monitor ROM, appearing at FE0000 to FE1FFF in the memory map. This ROM performs a simple system test after every reset, then it attempts to boot from disk. If the boot fails, or if the user requests it, there is also a command line monitor prompt. Details of the debugger are in the SDT manual, above.

Here is a dump of the monitor in my machine (no revision is noted on the EPROM labels, but on boot it says "SAGE II Startup Test [1.2]"). Beware that this is a dump from the viewpoint of the processor; in real life the file would need to be split into even and odd bytes to be burned into two EPROMs.

Intel HEX file for the monitor program

Boot Disks

As the Sage II uses the NEC 765 floppy disk controller, its disks should be readable and writable from any PC equipped with a 5.25" floppy drive of the right configuration (96 tpi, double sided).

SAGE4UTIL reports the floppy disk geometry as

David Erhart used the fantastic ImageDisk utility from Dave Dunfield to capture images of the system boot floppies. A PC that can boot into DOS and that has either double sided, double density (720KB) or a high density (1.2 MB) floppy drive should be enough for you to reconstitute boot disks for your Sage.

Pictures

The machine description above has image links scattered throughout. Here are links to the same pictures, labeled more clearly.

Links

Here are a few other links of significance on the Sage II computer:

Feedback

If you want to contact me for whatever reason, try me at jim@thebattles.net.

Other documents, software, peripherals, or even just an email with stories, are all welcomed. I'm happy to pay shipping for anything you are willing to donate.

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Last updated: February 26, 2017