a2000

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 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
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