Orao (computer)


Orao 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 was designed by Miroslav Kocijan to supersede Galeb. 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+.

History

The chief designer of Orao was Miroslav Kocijan, who previously constructed the basic motherboard for Galeb. 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.

Architecture

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.

Specifications

Math


10 REM PLOTS ONE PERIOD OF SINUS GRAPH
20 for x=0 to 128
30 y=64*sin
40 plot x,y+96
50 next
60 END

Physics


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/
40 NEXT

Output

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

Design team