Vintage Computers at Work

  • by

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.

Bytefest 2019

  • by

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

  • by

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

  • by

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

  • by

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

Commodore SX-64 (1984)

  • by

Commodore stated this as the first color portable computer. I’m not sure if it’s entirely true but it was quite common to have only monochrome screens in portable computers back then (Osborne, KayPro, Compaq/IBM Portable). I was surprised how small this machine is when I saw it in real life. Second surprise was its weight – with about 10 kilograms it is a heavy machine for its size. On the other hand for less than $1000 you could have a portable computer with a 5-inch color screen, 64KB of RAM and a built-in floppy drive to run advanced software like VisiCalc.

People see C64 mostly as a gaming machine. I’m not sure if this was so different in the 80s but SX-64 was not a huge success. It doesn’t make much sense for portable gaming and business customers were probably more interested in CP/M compatible machines (although more expensive).

Anyway, I like SX-64 a lot. It’s a very nice portable computer with a good color screen and a comfortable keyboard.