Orion-128


The Orion-128 is a DIY computer designed in Soviet Union. It was featured in the Radio magazine in 1990, other materials for the computer were published until 1996. It was the last Intel 8080-based DIY computer in Russia.

Overview

The Orion-128 used the same concepts as the Specialist and had similar specifications, with both advances and flaws. It gained more popularity because it was supported by a more popular magazine. In the early 1990s the computer was produced industrially at the Livny pilot plant of machine graphics means in Oryol Oblast. Much of the software for the Orion-128 was ported by hobbyists from the Specialist and the ZX Spectrum.

Technical specifications

"Orion" is partially compatible with "Radio-86RK" in terms of keyboard, standard ROM subroutines and data storage format on the cassette, and with another amateur radio computer, "Specialist" in terms of graphic screen format. Apparently, he also used the idea of an electronic disk from RAM from another domestic computer with 128 kb RAM - Okean-240. The Orion developers, they say, set themselves the task of creating an inexpensive, simple and affordable consumer PC with good graphics capabilities, and they succeeded. In the minimum configuration, ORION contains only 42 microcircuits, in the standard configuration there are only 59, and expensive or scarce components are not used, you can use obsolete series microcircuits. For the same reasons, the KR580VM80A was used as the CPU, as the cheapest and most affordable. Moreover, the Orion circuitry is such that the processor operates at its maximum frequency of 2.5 MHz without any delays. The same idea of transparent access to RAM is implemented, which was previously applied in the "Specialist" and its clones. Other domestic machines used WAIT cycles to synchronize the processor with the video part, which reduced performance by 25%. This made the Orion, along with the Corvette, the fastest domestic home computer on this processor. For example, Vector-06Ts, which has a much higher clock rate of 3 MHz, is inferior to Orion in terms of speed due to the slowdown of the processor by the video controller.
"Orion" has high graphics capabilities for this class of machines - a resolution of 384x256 allows good graphics in games, although the resolution is still insufficient for text processing; a full-fledged color mode is provided with its own color for each pixel, 4 colors selected from two palettes and visually the number of colors can be increased due to a mosaic of colored dots, as is done in CGA games. This mode is typical for many Western computers of this level ; and for games and texts there is a convenient 16-color mode.
The organization of the Orion screen is linear and very convenient for the programmer - the low byte of the address specifies the vertical position of the screen byte, and the high byte indicates its horizontal position. This simplified and accelerated the display of graphics on the screen. A color screen in 16-color mode consists of two planes - the graphics plane and the color plane. For text in a single-color window, this speeds up output and shifting, as before output, the window is first painted over, which halves the amount of output bytes per character, and with a video in the window, the color simply does not need to be changed. Also, in all video modes, Orion allows you to use up to 4 software-switchable screen buffers. This allows you to output to a currently invisible screen and then instantly turn it on, which eliminates the problems with flickering sprites in dynamic games and the need to deal with this due to interruptions, as in the ZX-Spectrum. On the Orion, even large sprites can be moved across the screen without flickering.
For Orion-128, its developers initially created the author's ORDOS operating system, designed to work not with a disk drive, but with a ROM disk, RAM disks and a tape recorder. ORDOS made it possible to work comfortably with a computer without having disk drives that were not available at that time. Of the serial home computers, the Junior FV-6506, which also used CP/M, had something similar.
As relative shortcomings of "Orion" can be noted only non-optimal screen resolution of 384 * 256 at a video signal frequency of 10 MHz. This leads to the need to use an ugly, and most importantly, non-byte 6*10 font, which is displayed 2.5 times slower than an 8*10 byte font. But in Corvette, Ocean and Vector, a 512 * 256 screen is used, therefore, even with a lower CPU speed and a larger screen buffer, their text processing is much faster and prettier, and the raster occupies the entire screen. As a disadvantage, sometimes they point to the lack of a hardware sound generator. This is possible because the authors understood that the gaming niche in the country was already occupied by ZX-Spectrum clones.
But the lack of hardware screen shift, contrary to the reviews on some sites, is not at all a disadvantage, because thanks to the vertically linear organization of the screen, the vertical shift of the screen by the stack is fast enough, and the horizontal shift is simply not needed.