swarm

Vienna 286: cleaning

It took me five hours to clean whole computer. I had to remove all components to properly clean the case, but It looks much better now. Anyway, the complete disassembly allowed me to take higher quality photos of all cards inside. I’ve never seen a standard desktop PC with so large mainboard – everything is done using many single-function chips instead of large multi-function chipsets (btw the missing chips are for an FDD controller).

Installed cards:

  • AST RAMvantage RAM card (supports up to 3 megs of XMS)
  • Western Digital WD1003A-WA2 HDD/FDD controller (connected to a ST-4038 hard drive)
  • GeniScan interface (for GeniScan hand scanners)
  • ATI Graphics Solution rev3 (the first ATI chip – supports Hercules and CGA)

Bringing “Vienna 286” back to life

A friend of mine found an early 286 computer from the 80s in his garage. It was built in 1987 in Austria and then sold to an engineering school in socialistic Czechoslovakia for an incredible amount of money. The system contains 8-MHz Intel 80286 & 80287, a 1.5MB RAM expansion card, a Hercules clone (the first ever PC graphics chip from ATI) and a 30-MB Seagate hard drive for the ST-506 interface. We were not sure if it worked after decades in garage but to our surprise, we were able to boot. The system was fully working once we set up CMOS variables.

A few notes:

  • Modern computers with USB floppy drives are still usable for creating and testing DOS boot floppies without a need for emulators
  • The Czech “old computing” community is very generous. We forgot to take a PS/2-DIN adaptor and didn’t want to go back to Prague for one (two hours of driving) so I wrote a message on Facebook and got a keyboard (with mechanical switches) for free from a person living in a city near us.
  • Copying a whole 30-MB disk drive over a 115 kb/s serial port is faster than copying modern drives over USB 3.0
  • Booting to DOS prompt takes only 12 seconds (including BIOS)
  • I had to find a generic BIOS setup utility, because the early Phoenix BIOS didn’t
    have it built-in. GSETUP31.EXE was a solution. Check this for good DOS stuff (more
    info in 00_index.txt).

Atari Stacy And a New Display

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You can still buy a new white-on-blue LCD for Atari Stacy (a 30 years old system). The reason is simple – the same screen is used in multiple medical/industrial devices. The result is better than backlight replacement we did on a different unit although the new screen is glossier. Now we have two fully working machines.

I don’t have much experience with 16-bit Atari computers so I was quite surprised that the system has also some tricks to get more than 16 colors our of the machine. Albeit not as useful as the HAM mode on Amiga, this is still impressive.

Tesla 3WN1660

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Tesla 3WN1660 Computer Mouse (made in Czechoslovakia):

Repairing PowerBook 100

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It took us three evenings to get two of the three PowerBooks back to life. The logic board of one of them was so damaged by leaked capacitors that it was impossible to fix it. The other two are now in a working state except for the SCSI hard drives. The most difficult part was to disassemble the display panel. The layer with liquid crystals contained several electrolytic capacitors that needed to be replaced as well. The original Conner drives did not properly spin up but that was expected behavior – I think that all first gen Conner 2.5-inch drives are already dead.

The only way to boot the laptop is to use an external floppy drive at the moment (or an external SCSI device). Running the System 6.0.8 from floppy is not very convenient. Fortunately, there is a nice solution. You can create a RAM disk, install the operating system into it and then set it as a boot device. PowerBook 100 is the only PowerBook with a persistent RAM disk function which content is backed up by three coin cell batteries. Data remains intact even after shutdown.

Apple PowerBook 100

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This is the smallest model from the first generation of PowerBooks. It was very thin and light for its time but didn’t have an internal floppy drive, which resulted in poor initial sales (before discounts). The logic board is based on a low-power version of 16-MHz Motorola 68000 coupled with up to 8 MB of RAM and 20 or 30-MB SCSI hard drives.

I have three non-working units and all of them need (at least) to replace bad capacitors. Their owner told me that I can keep one if I fix another for him.

CGA Color Palettes

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The infamous default 4-color palette with pink, cyan, black and white is probably the first thing that comes to mind when somebody starts to talk about CGA. I previously wrote a post about 16-color modes available for composite monitors but it’s good to add also something about the palettes for RGBI TTL monitors. These started to be used heavily when people stopped using TVs with their IBM PC compatibles.

The CGA palettes were designed for good viewing on NTSC TVs. That’s the reason behind the strange color combinations. The default one can, however, be modified using a video chip register – it replaces pink with red but also disables color burst on the composite output. Such trick was used in many games, but it did nothing on newer cards (EGA/VGA).

CGA also supports changing the color 0 (usually black) to any other color. Several games used this with the default palette to get blue, cyan, pink and white which allowed for better color transitions. Anyway, the easiest way to get more visually appealing games was to use the second palette – red, green, yellow and black.

CS:GO and Kids at School

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Today? Teaching kids how to make new maps in Counter-Strike: Global Offensive.. It took me six hours to learn the Hammer editor and another six hours to make the map shown on the pictures.

CP/M running on Sinclair ZX Spectrum +3

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Unlike previous ZX Spectrum computers, +3 is equipped with an internal 3-inch floppy drive (compatible with Amstrad computers) and it is fully capable of running CP/M. The system runs snappier and more responsive than Commodore 128 in the CP/M mode but there are two caveats. Multiple keys are missing in the crippled keyboard layout and these are replaced with cumbersome keyboard shortcuts. This can be especially annoying when working with spreadsheets.

Another issue comes from the fact that the video circuit works in a resolution of 256×192 so it cannot handle the standard 80×24 text-mode typical for CP/M machines. The computer normally displays only 32 characters per row which would not be enough for any CP/M program. The +3 version of CP/M therefore uses a reduced font resolution with just 5×8 pixels for each character (including space between characters). Such font allows to display 51×24 characters and that’s the default text mode when +3 is booted in CP/M.

Of course not all programs work correctly with the reduced screen size so there is a program called SET24x80.COM. It provides a virtual 80×24 screen and you can quickly switch between displaying the first 51 columns or last 51 columns of the screen using a keystroke.