Dubna 48K

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Dubna 48K
1. The Dubna 48K
Type Home computer
Released 1991
Processor analogue of Zilog Z80 @ 1.875 MHz
Memory 48 KB
Operating system Sinclair BASIC
2. Mainboard
2. Mainboard
3. CPU and ROM
3. CPU and ROM
4. RAM
4. RAM

The Dubna 48K (Дубна 48К) is a Soviet clone of the ZX Spectrum home computer. It was based on an analogue of the Zilog Z80 microprocessor. Its name comes from Dubna, a town near Moscow where it was produced, and "48K" stands for 48 KBs of RAM.

According to the manual, this computer was intended for:

  • studying the principles of PC operation
  • various kinds of calculations
  • "intellectual games"

By the time this computer was released (1991), there were already much more powerful x86 CPUs and commercially available advanced operating systems, such as Unix, DOS and Windows. The Dubna 48K had only a built-in BASIC interpreter, and loaded its programs from a cassette recorder, so evidently, it couldn't run any of modern operating systems, and as such, wasn't suitable for "studying the principles of PC operation". However, the Dubna 48K and many other Z80 clones, hopelessly outdated by that time, were largely introduced in high schools of Soviet Union. According to a contemporary who studied at a school in Chelyabinsk in the 1980s, they used wooden plates with keyboard drawn on them, as the schools lacked PCs greatly for the lessons of Computer Science. So even these outdated computers were considered as a great boon.

Moreover, most of the games for the Z80 were already available for Nintendo's 8-bit game console, marketed in Russia under the brand Dendy, and it was a much cheaper, more reliable and easier way of playing games, so it became clear that the Dubna 48K wasn't in much demand for home users.

Contents

[edit] Included items

The Dubna 48K was shipped with the following units:

  • Main unit ("data processing unit", as stated on its back side), with mainboard and built-in keyboard
  • External power unit
  • Video adapter for connecting the computer to the TV set
  • BASIC programming manual
  • Reference book, including complete schematic circuit

Additionally, there were some optional items:

  • Joystick
  • 32 cm (12") colour monitor

The computer could also connect to a ZX Microdrive, but such device was never included.

[edit] Technical Details

  • CPU: 1.875 MHz, 8-bit
  • RAM: 48 KB (in 16 KR565-series chips, see picture 4)
  • ROM: 16 KB (picture 3, two white chips in the middle)
  • Resolution: 256×192 pixels, or 24 rows of 32 characters each
  • Number of colours: 8 colours in either normal or bright mode, which gives 15 shades (black is the same in both modes)
  • RS-232 port
  • Power unit: 5V, 1.7 A
  • Dimensions of main unit: 52×320×255

[edit] Other facts

  • The Dubna 48K has a steel case, while most other Spectrum clones had plastic cases.
  • There are people who buy used PCs like the Dubna 48K. The reason for this is that these computers contain little amounts of gold and silver. For example, the Dubna 48K contains (according to the manual) 1 g of gold, 3 g of silver and 0.1 g of platinum.
  • Due to lack of some chip, it could be replaced by several others. How to do this is described in the reference book shipped with the computer. For example, in the upper part of picture 4 you can see a small board with 3 chips installed in place of a single K555IR9.
  • Unlike the Dubna 48K, most Z80 computers were assembled at home by amateurs, inspired by numerous articles in the Radio magazine. Programs for these computers, usually taking many pages (in binary codes) and BASIC programs were also printed in this magazine and had to be typed in manually.

[edit] See also

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