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.

Early Apple Macintosh PowerBooks

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PowerBook 100 has a special place in my heart. I had one back in the 1990s and I loved its big trackball, comfortable keyboard and proper palmrest area – features that were not present in typical PC laptops. Other early PowerBooks were not as small and light as the PowerBook 100, but they shared many design decisions with it. I perfectly understand people who bought and used these computers when they were new. On the other side, I cannot agree with those who see early PowerBooks as universally superior machines to PC notebooks. That’s just not true.

From time to time, I see nonsense statements like that PowerBooks were the first laptops with stereo sound, optical drives, docking stations or other features. Not sure at the moment, but I think that you can find some of these statements even on Wikipedia. However, all of these features were previously available in PC laptops.

In fact, the generations of early PowerBooks that came after the first generation were not considered very innovative back then. Just a few examples:

  • Support for gray-scale video modes on internal screens was added at the end of 1992. Until that, it was possible to run only programs that were written to work with the black and white mode. All VGA-equipped PC laptops supported gray scale and could also translate colors into levels of grey in hardware (no OS or program support was required).
  • Unlike with PC laptops, there was no support for features like color LCD screens, PCMCIA expansion cards and microprocessors with built-in power management capabilities in 1992.
  • There was no graphics acceleration in Apple’s video circuits which resulted in significantly slower screen redraw. This started to be a problem when Apple offered PowerBooks with color screens where the graphics core had to process far more data. The first color PowerBooks with competitively fast graphics chips were available after Apple started to use generic PCI solutions from the PC world (mostly Chips & Technologies, later ATI).
  • Many of the PowerBook graphics chips didn’t support more than 256 colors on external screens even in 1994. Lower-end machines didn’t even have a video output for an external screen.

The first color TFT PowerBook – 180c – was released in August, 1993 – almost a year after major PC brands released their first TFT portables. The PowerBook 180c was equipped with a small 8.4-inch 640×480 screen when PC laptops often used 9.5-inch screens and there were some with even 10.5-inch screens (like the famous IBM ThinkPad 700C – December, 1992). That was not the only issue – it lasted only about an hour on one charge because (unlike PC laptops) it didn’t have a 3.3V CPU, advanced power management features and NiMH batteries.

Heat and power consumption was so big issue with Motorola 68040 that Apple had to release 040-based PowerBooks with a version of the CPU that didn’t have a math coprocessor. Thus, programs that used it heavily were twice as fast when running on the previous generation of high-end 030-based PowerBooks. 486DX-based PC laptops could run the same code four times as fast.

The machines on the photos:

(1) Apple PowerBook 100 (1991), 16-MHz 68000, 4MB RAM, 20MB HDD
(2) Toshiba T2200SX (1991), 20-MHz 386SX, 4MB RAM, 60MB HDD
(3) Apple PowerBook 145 (1993), 25-MHz 68030, 8MB RAM, 80MB HDD

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.

Atari STacy 2 (1989)

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It would be a shame to not share the rest of Atari STacy photos. This was my first experience with this machine and it was wonderful. The large trackball is a pleasure to use and the only thing I don’t like are small arrow keys.

The machine is in perfect condition (the display is less bright though). Its internal 640×400 1-bit monochrome LCD operates in the ST High mode and it doesn’t support any other mode. You can use STacy for playing games but you need to attach a TV set or a color monitor then.

You’ve probably noticed that there is a battery LED indicator. The machine doesn’t have a battery (other than the one for RTC backup) because Atari was not satisfied with a very low battery life and decided to not include it (in order to lower the price).