Vintage Computers at Work

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We prepared a small room with old computers as a part of a bigger event at work. After careful consideration, we selected Atari 800XL and Commodore Amiga 500 for the contest purposes. Atari was running Space Invaders and each visitor played with the highest difficulty (three lives, level 12). For Amiga, we chose Pinball Dreams and the goal was to get the highest score using just a single ball.

To make the room more appealing, we brought several old computer magazines and 80s props. Curious visitors could also experience ZX Spectrum+ with the Who Dares Wins game. The feedback on our room was very positive and people were talking a lot about their first computers there. However, the biggest surprise for me is that the joystick survived all the players. Some of them gave it a hard time.

Multivision 2000 (Amiga Scan-Doubler)

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Working with old Amiga computers with their original color monitors is always a painful experience. Especially here in Europe where these screens run at 50Hz. Fortunately, my Amiga 2000 is equipped with a Multivision 2000 scan-doubler card that not only doubles H-sync from 15.75kHz to 31.5kHz (to make the output compatible with VGA monitors) but it also allows a user to increase refresh rates up to 100Hz.

I wanted to show this computer on Bytefest (a vintage computer show) and I decided to show it with a CRT (LCDs always ruin the experience). That created an ideal situation to check how this “software controllable refresh rates” feature works. The manufacturer of the card (3-State) bundled a diskette with a simple program that allows you to find the optimum refresh rate using multiple sliders and the way it works is compatible even with old simple VGA screens from the early 1990s.

The picture frequency is increased when a user decreases the number of video lines. Speed of drawing of each line is still the same. The computer just generates fewer lines, which means that a single frame takes less time and the next one can start sooner.

I switched Workbench into the interlaced mode (512 lines instead of 256) and then used the bundled Sync Master tool to decrease the number of lines close to the original non-interlaced resolution. As a result, I got nice and steady 80Hz on a standard VGA screen, which allowed me to work with the computer for hours without eye strain. This is a perfect setup for office/productivity work. However, be prepared that this tool doesn’t work well with applications that open their own screens a display outside Workbench (you need to revert it to default before starting such application).

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).

Amiga for Bytefest

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I’m still preparing my computers for the upcoming Bytefest. Amiga 2000 with a A2088XT PC emulator card is the second computer I want to have there. Unlike others, I want to show the computer with Kickstart 1.3 / Workbench 1.3, original upgrades and late-80s programs.

I often see only heavily expanded Amiga systems with latest versions of Workbench, PowerPC accelerators and PCI cards. However, these machines don’t say much about this platform when it was really used by professionals.

Amiga 2000 (1987) – Part 2

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It took me two years to find some time to disassemble the machine and then another year to start fixing it. Repairing the PSU with the blown EMI suppression capacitor was an easy task and that’s what we started with. Worse part was the instability – machine often crashed to a guru meditation error during certain tasks and sometimes a restart resulted in a “color screen” error.

David created and programmed a small device with eight differential inputs for voltage measurement (and logging) so we could check if the electrolytic capacitors did their job properly. To our surprise, they were fine. We also tried different programs to test memory and other hardware but the computer successfully passed all the tests.

Based on the Guru error codes, we found the root cause in the faulty EPROM chip (Kickstart 3.1). It started to lose data and reading of certain regions of the chip was sometimes affected. Thus, CPU executed faulty code (like a word or long word access on an odd address boundary).

The system is now running with Kickstart 1.3 and Workbench 1.3 and all original upgrades are inside except one. The Commodore A2630 accelerator card (25MHz 68030+98882, 2MB 32-bit RAM) crashes with dark blue and green screens and I’m afraid that there is a mechanical issue.

Next steps: Fix A2630 and reprogram the EPROM chip.

Amiga 2000 (1987) – Part 1

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This quite a nice upgraded machine waited two years for a repair. Now I am on sickness leave so I finally have enough time to look inside. The logic board is covered with a lot of dust and the EMI suppression capacitor exploded so it needs to be replaced. Before the explosion (which happened when the machine was off) there was also another issue – it could not boot without the (CPU) accelerator card and even then, under certain situations it displayed the green screen error (= chip RAM).

Except for the CF-IDE adaptor, there are no modern upgrades in this A2000. The logic board contains just 68000 with 1MB of chip RAM and it is expanded with following:

  • A2630 rev 9 – an accelerator board with 25-MHz MC68030 CPU, MC68882 FPU and 2MB of 32-bit (fast) RAM
  • IDE controller for a hard drive and CD-ROM
  • Multivision 2000 – a scan-doubler (VGA compatible) with a stereo audio amplifier
  • A25000 – 2MB RAM expansion
  • PC Emulator A2000 – a PC XT emulator card with 4.77-MHz 8088 and own RAM
  • Tseng ET4000AX – a video card that allows to display the DOS session on a separate VGA

Another World

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Another World is one of my top 10 favorite games. I love cinematic platformers. FlashBack, Blackthorne (except the ugly Mac version), Oddworld: Abe’s Odyssey/Exodus and Hearts of Darkness – all of them are great games but Another World has a very special place in my heart. I still remember how sad I was as a kid when Lester collapsed and his alien friend took him away at the end of the game. The cinematic character of the game was something completely new for me.

TCP/IP on Amiga

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It was a very successful day today because I’ve managed to get TCP/IP working on Amiga 1200. There is a problem that the first version of Amiga OS with built-in TCP/IP stack is from 1999… and I don’t have it and I don’t want to install it on such old machine. There were some third-party packages available before this date but they were not for free or even cheap (~$50).

I’ve installed AmiTCP which looks like something ported from UNIX (like many text-mode software packages on Amiga). There are installation scripts where you can configure all addresses and select the NIC driver but the result is not working with PCMCIA cards. I had to change three script files by trying various combinations (and install two PCMCIA OS fixes) before it started to use the network driver the right way. Whole procedure was definitely more complicated than on any other operating system I’ve ever used.

This is the end of copying software to/from Amiga using floppies or cortex floppy emulator. I can download anything using FTP now. Hooray!

Btw I use 3com Etherlink III (3C589C) PCMCIA network card which is supported in many operating systems. I’ve used it also with Windows 95/3.x/NT3.51/4.0, Windows 2000/XP, Windows CE, Mac OS 7.5 and many older Linux boxes. If you needs PCMCIA networking solution, this is the best one.

Phase5 CyberVision 64/3D (1996)

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CyberVision 64/3D is a graphics accelerator for Zorro II/III slots used in professional Amiga computers. It was introduced in 1996 and uses S3 ViRGE chipset which was for a very short time period something like a leader of the home 3D graphics market (ViRGE stands for Virtual Reality Graphics Engine).

S3 ViRGE (86C325) was designed for PCs with PCI bus so Phase5 developers had to add some programmable logic to convert signals from the Zorro bus used in Amiga. The card is autosensing and can work with Amiga 2000 (1987) where only 16bit slots are used. Full 32bit transfers are available when the card is inserted in newer Amiga computers (A3000, A4000).

The first problem was high price ($399) when compared to the PC world. You could buy a way more powerful 3Dfx Voodoo Graphics PCI accelerator board for $299 and there was plenty of decent 2D cards under $100 for standard PCs. In addition to price there was no support for OpenGL 3D acceleration in Amiga OS in mid-90s. The main reasons for buying this card were its fast 2D acceleration (in comparison with outdated Amiga on-board chipsets) and support for 1024×768 with 16 millions of colors on a standard VGA monitor.

3D modeling in 1988

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Long time ago (before I went to college and then got a job) I played a lot with 3D modeling software on PC. My favorite one was LightWave3D. Recently I tried its very beginning – there is something called VideoScape 3D which is kind of predecessor. In the package there is a small program Designer3D which (unlike other 1988 modelers for home micros) allows to make a 3D model using graphical interface instead of text commands.

You can see in the video how creepy the interface was. There are three viewports that cannot be resized or zoomed. I’ve modelled a simple “space ship” with only 20 polygons and it took me an hour to do this.

However, I see very interesting that there is a 10-page manual program that can describe all functions of the program so even somebody who never did anything in 3D can understand it. This is not so easy with today’s 3D modelers.