ibm

50-line text mode on a gas-plasma screen

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I took this photo while working on the MS QuickBasic version of our benchmark (previously written in C and Assembly). The goal was to compare speed of different languages and compilers. This required me to relearn BASIC so I always needed to see online help, my BASIC code and the original C code on a single screen. Switching a screen into the VGA 80×50-character mode is invaluable in these situations.

Regarding the results: I tested all versions of our benchmark, which is mostly about integer performance and memory access (similar to compiling and XML parsing), on this IBM PS/2 P70 with a 20-MHz 386 (DX). Interpreted QuickBasic 4.5 version was used as a baseline (1x). These are the speed-ups:

  • Compiled QuickBasic = 3x
  • Borland C++ (8086 instructions) = 15x
  • Borland C++ (386 instructions) = 33x
  • Hand-tuned Assembly (386 protected mode) = 70x
  • Metaware High C/C++ (386 protected mode) = 70x

Repairing IBM PS/2 P70 before Bytefest

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I shared a photo of computers we brought to Bytefest (a vintage computer show in Czech Republic). IBM PS/2 P70 was one of those which needed fixing before the show. In this case, there were issues with an Alps floppy drive and power supply. I have to admit that this was one of the most painful disassemblies we did.

This is a dream machine for a user but total nightmare for maintenance. One example – it was necessary to disassemble a half of the unit just to connect a floppy cable back to the drive.

Bytefest 2018

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I’ve brought some of my computers to Bytefest (a big Czech vintage computer show): Apple PowerBook 100 with an external floppy drive, IBM PS/2 P70 as a cool gas-plasma-screen serial terminal, SGI O2 (used only as a hard drive cloning machine running in headless mode), SGI Octane2 with all necessary peripherals and DELL Precision M50 for sharing wireless Internet connection with my other machines (and also to show how the graphics workstation market changed in less than two years from Octane2).

Vienna 286: cleaning

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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

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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).

Flight Simulator 3.0 Running on IBM PC with CGA Graphics

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Users with composite monitors (or TV sets) could use the 16-color video mode that was based on the same trick as was used in Apple II. On the other side, it was not possible to use more than four colors at the same time in the game when the system was connected to a standard RGBI (TTL) monitor. This was typical for many early PC games.

Windows 3.1 on Gas-Plasma Displays

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Windows 3.1 running on IBM PS/2 P70 with the gas-plasma display. There was a special color scheme included with Windows 3.x specifically targeted for use with this type of screens (to minimize the screen burning effect).

Laptop Display Troubles

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IBM PS/2 Model P70 (1989) on the left side and Toshiba T2200SX (1991) on the right side. The IBM machine is equipped with a gas-plasma display and Toshiba has a typical side-lit passive-matrix LCD. The photo can hardly show how superior the plasma screen is. Its black is so deep that it cannot be beaten with any modern LCD. It is as fast as CRT monitors (unlike passive-matrix LCDs with 300ms response time) and as sharp as active-matrix LCDs (that were introduced a year after this machine).

There are no plasma screens in laptops today so where was the catch? It was in power consumption which was significantly higher. Typical machine with a gas-plasma display was either AC-only or with battery life usually up to one hour. Active matrix displays started to be affordable in 1992-1993 and with their color capability and lower power consumption they pushed plasma screens out of the market. Until then gas-plasma displays were the hi-end choice for many portables.

My P70 in action: https://www.youtube.com/watch?v=RaaIg8mrBkE

IBM RT (RISC Technology)

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IBM PC was not intended as a high-performance workstation back in early 80s. It could hardly be so with its slow CPU, limited graphics capability and a single-task operating system. However, IBM had an answer for performance demanding users requiring multi-tasking UNIX workstations. It was called IBM RT (known also as IBM RT PC) and was introduced in 1986.

There is some interesting history behind this computer. IBM had a RISC technology way before others (early 70s) but it required to pass a lot of internal processes and bureaucracy stuff to get it working in a custom chipset – IBM 801 CPU. IBM RAMP was introduced in 1986 and it was a spin-off project of the original CPU architecture. This 32-bit CPU was made of multiple chips on a single board and the computer needed another board to handle floating-point calculations in hardware (which was optional).

The first (6-Mhz) version of the system was quite underpowered in comparison with workstations based on MIPS R2000 RISC CPUs. This was not the only issue on the competitive market with well-established players like Apollo, DEC, HP and Sun. AIX* (IBM’s UNIX implementation) was not 4.2BSD compatible which resulted in limited software availability. IBM didn’t give much support to this product and company salesmen had no reason to push it due to low commissions.

The system used custom 32-bit bus for CPU cards and memory. Other cards like graphics adapters or storage (ST-506, ESDI) and network (token ring, Ethernet) controllers were designed for standard 16-bit AT slots fully compatible with PC line.

There were four graphics adapters available. Two with resolution of 720×512 in monochrome (black & white) or with 16 colors (out of palette of 64 colors) which were combined with 15-inch CRTs. Other two adapters offered 1024×768 (1-bit monochrome) or 1024×1024 with 256 colors out palette of 4096 colors and were combined with 19-inch CRTs (with 60hz refresh rate). Unlike standard PC graphics cards, these supported BitBlt transfers, line draw and image copy/merge to offload graphics operations from main CPU.

IBM RT was used for certain CAD applications and for shopping store control but it was not very successful on the workstation market.

*) AIX stands for Advanced Interactive Executive

Kids and Old Computers

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There is a way to see many old computers running in one room in Czech Republic. It’s called Bytefest and it is probably the biggest public retrocomputing event in the country. I took about twenty computers in my car with me this year in order to show the evolution of portable computers.

There were a lot of people walking around and some of them brought their kids. It is somehow nice to see little kids trying to do something with computers that are few decades older than they are. When they grow up there is a high chance that these computers will not work anymore.