sgi

Finally, there is a proper computer to run Windows!

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MIPS Magnum 4000 is derived from the Microsoft Jazz development platform which was internally used to develop Windows NT (3.1). Then, it was ported to other CPU architectures incl. x86. Windows on MIPS was not successful but it was an important part of the history.

From the outside, the Magnum 4000 looked like a regular PC. There was a 100-MHz MIPS R4000 (on a 50-MHz internal bus) and 32-bit EISA bus for standard expansion cards (x86 option ROMs could be executed via emulation). The interesting part (for me) is the graphics hardware. There is a special 64-bit slot that allows attaching the graphics card directly to the processor bus to provide the maximum bandwidth. The card is based on a little-known INMOS G364 frame buffer with 2MB of video RAM. It supports only 256-color modes, no VGA compatibility and up to 1280×1024.

There are two parts that are the most interesting for me:

  1. You set the screeresolution in the ARC firmware and you have the same resolution during the boot and in Windows (where there is no way to change it). This allows using fixed-sync CRTs.
  2. There is no hardware acceleration (aside the hardware mouse cursor drawing) and not BitBlt. The philosophy here was to create no bottlenecks between the CPU and video memory and allow CPU to use its own full raw power for drawing.

TMM, the owner of the machine also has a nice step-by-step guide how to emulate it in QEMU: https://blog.tmm.cx/2022/06/11/running-windows-nt-4-mips-on-qemu-in-3-easy-steps/

Although the ARC firmware is crude, it apparently has multiple fonts used based on the selected resolution:

UNIX on Bytefest 2024

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Three lovely #UNIX machines networked together during Bytefest 2024.

Btw Rhapsody OS is surprisingly a nice experience compared to the standard (pre-X) Mac OS. The BlueBox environment (paravirtualized MacOS 8.1) does not support any direct hardware access (3D, video acceleration), but 2D graphics works just as fast as on bare metal MacOS.

More SGI computers

I got some new SGI computers. I was surprised because I thought the SGI guys from the Czech Republic gave me all their leftovers. I had to go to one of the original SGI offices in Brno this time. The office design was very 90s and there were classic SGI artworks on the walls. All the people there are now HPE employees but many of them started there working for SGI when every employee had an Indy or O2 on their desk.

The “loot” contains:

  • Two SGI O2 / MIPS R5000 / 2x SCSI HDD / the one with the older logo has an analog AV module installed
  • SGI Visual Workstation 320 / 1x Pentium II / a basic configuration with an IDE HDD
  • SGI Challenge / MIPS R5000 / basically an Indy without audio ports and a graphics card
  • Two sets of keyboards and mice, the PS/2 one is for O2 and the USB one for SGI 320

SGI IrisVision – a $4,995 3D accelerator in 1990

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After years, I’ve finished a long in-depth write-up about an interesting piece of history – the SGI IrisVision 3D accelerator from 1990. It was a scaled-down version of the graphics board set from the SGI Personal IRIS and was intended for PC compatibles (16-bit AT bus) and PS/2 computers (MCA).

See the deep dive article here: https://retro.swarm.cz/sgi-irisvision-add-in-3d-accelerator-for-pc-1990/

The whole thing started when IBM licensed the graphics hardware and the IRIS GL 3D API for their IBM RS/6000 UNIX workstations. Although the IrisVision was not very successful (like all 3D accelerators of the era), it is cool that IRIS GL programs could run under DOS.

At the end of the article, there is a video showing the card in action in a high-end IBM PS/2 Model 70 with a 25-MHz Intel 386 and 387.

SGI Indy CMOS Battery Fix

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Replacing a dead CMOS battery in a Dallas NVRAM/clock chip without using proper tools. This was for our precious Silicon Graphics Inc. Indy UNIX workstation.

Shark demo (1994) running on a SGI O2 workstation

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This is one of the demos that were used by Silicon Graphics and Nintendo to show the graphics features of their upcoming game console (Project Reality / Ultra 64 / Nintendo 64) during CES in 1994.

SGI used an Onyx supercomputer to run the demo. I recorded it in 1024×768 (true-color) on a much less powerful SGI O2 workstation (released in 1996). O2 is based on a graphics architecture similar to what was actually used in Nintendo 64. It was a perfect fit for an inexpensive highly-integrated computer as well as a game console.

I would rather use a different SGI computer (Octane2 was my first choice), but O2 was the only machine that was compatible with my cheap VGA-to-HDMI converter.

Bytefest 2019

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These were the computers we brought to Bytefest – a Czech vintage computer show. David and I decided not to bring more than two desktop systems. Amiga 2000 was an obvious choice – we fixed it not a long time ago and I played a lot with it recently. The other computer was SGI Indy with the original set of peripherals including the Indycam camera. There are not many vintage UNIX computers to see on vintage computer shows in this country. Thus, it is my duty to bring at least one every year.

The Aritma Minigraf plotter sitting on top of the Indy was connected using one of the Indy’s serial ports though a special ARM-based module that David built. The module contained the control software that allowed it to draw faster and with better precision than the plotter was originally designed for. From time to time, there were couple of people standing in front of the plotter, being hypnotized by the smooth movement of the pen. The Indy itself was communicating with the module as a serial terminal with the ability to send HPGL files that needed to be drawn.

I’d never played that much with Indy before (aside creating the OpenGL 1.0 version of our 3D graphics benchmark) and this was a nice experience. The graphics card in our Indy is able to display no more than 256 colors (or 16 colors for double-buffered 3D), but it’s pretty fast and allows you to have a different 256-color palette for an active window and the rest of the system. Therefore, the color flickering effects are minimized in comparison with PCs set to 256-color modes. I was surprised by the visual quality of the composite input from Nintendo 64 in 256 colors.

Commodore Amiga 2000 was configured to show the capability of this platform during the late 80s (thus, Workbench 1.3 and Kickstart 1.3 only). It didn’t have any accelerator board and the only expansions were a simple hard disk controller, 2-MB fast RAM card and A2088XT PC emulator (with an 8088 and 512kB of RAM). During the show, I also added an ISA card with a serial port (for Microsoft InterLink purposes) and a VGA adapter.

The other devices that we showed were: Apple PowerBook 100 (this year with a working hard drive and full of software), Digital DECpc 325SLC (because a 386 with color LCD is cool) and HP OmniBook 900 (just a service laptop to convert the Wi-Fi Internet into a cable form for the Indy).

Preparing my SGI Indy for a vintage computer event

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Bytefest 2019 is coming and I have only two weeks to prepare all the machines I want to take with me. I want to the show this Indy with a Nintendo 64 game console because Indys were often used for N64 game development (after all, N64 hardware was designed by SGI). It is nice to see that Indy’s VINO interface supports progressive scanning (used by game consoles and old 8bit computers) on its composite/S-Video inputs – unlike newer SGI O2 and SGI Visual Workstation 320. Anyway, the main planned part is to connect a vintage Czechoslovakia plotter (Aritma Minigraf) using our custom interface (modified to use a serial port) and plot processed images of visitors taken using the Indy’s bundled webcam.

I’m surprised that serial ports on Indy support speeds only up to 38.4 kb/s. Pretty slow for a computer introduced in 1993. Maybe that’s one of the reasons why the serial port speed was not even mentioned in the user guide. They just didn’t care.

Certain Impact on SGI

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This is my favorite photo from the Bytefest vintage computer show last year. A little girl playing Certain Impact on my SGI Octane2. Certain Impact is a flight simulator created by Paradigm for SGI in 1995. It was used as a graphics demo for the Indigo2 IMPACT line of workstations.

SGI High IMPACT Graphics (1995)

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SGI Indigo2 IMPACT systems were the best workstations for game development and other activities involving textured 3D rendering in 1995. My system is equipped with High IMPACT Graphics, which is a two-card solution with a dedicated geometry engine (one million triangles/s), raster engine with two pixel processors (two pixel per cycle, 60-70 textured Mpixels/s), 12MB of pixel memory and a single texture-mapping unit with its own 1MB of texture memory.

The high-end option was called Maximum IMPACT Graphics. It took three slots in the computer and doubled the rasterisation performance by using exactly the same principle that was later used by 3Dfx Voodoo2 SLI (scan line interleaving).

The 3D performance of SGI Indigo2 IMPACT was years ahead of PCs and other workstations. In fact, 3Dfx Voodoo2, the best gaming 3D accelerator for PCs in 1998, had similar performance to High IMPACT graphics but unlike the IMPACT series, it didn’t support windowed rendering, 32-bit color precision and high resolutions.

The last two photos show Indigo2 IMPACT systems during the development of Final Fantasy VII (source: Sony press kit).

GPUbench results – compare the SGI Maximum IMPACT performance with other 3D accelerators of the same era.