|Release date||Yugoslavia: 1984|
|Operating system||Orao BASIC|
|CPU||MOS Technology 6502 at 1 MHz|
|Memory||16 KB / 32 KB|
|Display||RF modulator (video)|
|Sound||internal speaker (audio, early models) or three-channel audio via RF modulator (audio, later models)|
Orao (en. Eagle) was an 8-bit computer developed by PEL Varaždin in 1984. Its marketing and distribution was done by Velebit Informatika. It was used as a standard primary school and secondary school computer in Croatia and Vojvodina from 1985 to 1991.
Orao (code named YU102) was designed by Miroslav Kocijan to supersede Galeb (code named YU101). The goal was to make a better computer, yet with less components, easier to produce and less expensive. The initial version, dubbed Orao MR102, was succeeded by Orao 64 and Orao+.
The chief designer of Orao was Miroslav Kocijan, who previously constructed the basic motherboard for Galeb (working name YU101). Galeb was inspired by computers Compukit UK101, Ohio Scientific Superboard and Ohio Scientific Superboard II which appeared in the United Kingdom and the United States in 1979 and were cheaper than the Apple II, Commodore PET and TRS-80. Driven by the challenge of Anthony Madidi, Miroslav Kocijan began to develop a computer that is supposed to be more advanced than the Galeb with fewer components, easier to produce, better graphics, performance and a more affordable price. The working title of the new project was YU102.
Miroslav Kocijan managed to gather around him a group of people who helped in the development of electronic components and software. Kocijan had the idea to commercialize Orao, and was able to convince Rajko Ivanusic, director of PEL, to support the idea. In the market of the former Yugoslavia, where the purchase of home computers were disabled due to high tariffs and due to the low purchasing power of citizens and schools computers were unattainable, the idea of mass-produced home computers made sense.
Serial production and price
The price of Orao was originally set to be around 55.000 Yugoslav dinars, however the price rose to 80.000 dinars. The production began in the summer of 1984. Since the only imported components were integrated circuits which were hard to acquire in Yugoslavia because of strict monetary politics, PEL Varaždin itself financed the imports of these components, which enabled a cheaper final product. Occasional problems that occurred in the serial production were related to the construction of certain external parts and overheating.
Lack of supported software
Since the Orao was not compatible with any home computer of the time, its software offering was scarce due to the lack of software companies whose products supported the platform.
Lack of capabilities
That was one of most common sentences related to 8-bit school computer. Result of that statement is chapter above.
The graphics were controlled by a special circuit, not by the main processor as it was the case in many other home computers because Kocijan's intention was to create a graphical computer similar to Xerox Alto, or Macintosh, and as such, he had it utilize bitmap graphics. The resolution was 256x256 dots, for up to 196,608 bits of VRAM as the graphics could need no more than three bits per pixel. Such a resolution was chosen for square dots, which enabled easy writing of graphical programs. The resolution of text was 32x32, and every character was rendered in an 8x8 field. The designers of Orao went an additional step further to create a computer which could be far more easily expanded, connect with a printer and establish a net connection through RS-232.
- CPU: MOS Technology 6502 at 1 MHz
- Read-Only Memory: 16 KB (with BASIC interpreter and Machine code monitor)
- RAM: 16 KB (expandable to 32 KB)
- VRAM up to 24 KB
- Graphics: monochrome 256×256 pixels, in up to 8 shades of gray
- Text mode: 32 lines with 32 characters each
- 72 chars in one BASIC line
- Sound: single-channel, 5 octaves through built-in loudspeaker
- Computer keyboard: 61-key QWERTZ
- I/O ports: video and RF TV out, cassette tape interface (DIN-5), RS-232 (D-25), Edge expansion connector
- Peripherals: 5.25" floppy drive, Printer
- Price: 55,000 dinars planned but increased to 80,000 during production
10 REM PLOTS ONE PERIOD OF SINUS GRAPH 20 for x=0 to 128 30 y=64*sin(3.14159*x/64) 40 plot x,y+96 50 next 60 END
5 REM CONVERTS KM/H TO M/S 10 PRINT"KM/H M/S" 20 FOR SP=0 TO 60 30 PRINT SP,SP*1000/(60*60) 40 NEXT
RUN KM/H M/S 0 0 1 .277777778 2 .555555556 3 .833333333 4 1.11111111 5 1.38888889 6 1.66666667 7 1.94444445 8 2.22222222 9 2.5 10 2.77777778 11 3.05555556 12 3.33333333 13 3.61111111 14 3.88888889 15 4.16666667 16 4.44444445 17 4.72222222 18 5 19 5.27777778 20 5.55555556 21 5.83333334 22 6.11111111 23 6.38888889 24 6.66666667 25 6.94444445 26 7.22222223 27 7.5 28 7.77777778 29 8.05555556 30 8.33333333 31 8.61111112 32 8.88888889 33 9.16666667 34 9.44444445 35 9.72222223 36 10 37 10.2777778 38 10.5555556 39 10.8333333 40 11.1111111 41 11.3888889 42 11.6666667 43 11.9444444 44 12.2222222 45 12.5 46 12.7777778 47 13.0555556 48 13.3333333 49 13.6111111 50 13.8888889 51 14.1666667 52 14.4444444 53 14.7222222 54 15 55 15.2777778 56 15.5555556 57 15.8333333 58 16.1111111 59 16.3888889 60 16.6666667
Machine code/Assembly example
1000 A9 7F LDA #7F 1002 85 E2 STA E2 ; x center 1004 85 E3 STA E3 ; y center 1006 A9 6F LDA #6F 1008 85 F8 STA F8 ; radius 100A 20 06 FF JSR FF06 ; draw circle 100D C6 E2 DEC E2 ; decrement x center 100F C6 E3 DEC E3 ; decrement y center 1011 A5 F8 LDA F8 1013 38 SEC 1014 E9 04 SBC #04 ; reduce radius for four points 1016 85 F8 STA F8 ; store it 1018 C9 21 CMP #21 ; compare with 0x21 101A B0 EE BCS 100A ; bigger or equal ? yes, draw again 101C 60 RTS ; no, return
- Miroslav Kocijan
- Branko Zebec
- Ivan Pongračić
- Anđelko Kršić
- Damir Šafarić
- Davorin Krizman
- Zdravko Melnjak
- Vjekoslav Prstec
- Dražen Zlatarek
- Orao page at old-computers.com
- Orao implementation in FPGA
- Another Orao implementation in FPGA
- MESS, Multi-System Emulator which supports Orao
- Orao emulator with source code and some software, as well as Orao 2007 recreation of original computer
- Orao Emulator written in C#
- Orao Emulator for Android
- ORAO BASKET
- Orao Emulator in web browser
- Orao Emulator in Python
- Browser Orao Emulator as standard web site, using Blazor/C#
- Browser Orao Emulator as Web Assembly app, can work offline in modern browsers