Elwro Computers -  Elwro 804 (Junior)

Elwro Junior 800-4 (Prototype)

THe Elwro 800-4 Junior PC was an Elwro 800-3 Junior with new capabilities. It no longer had the toy piano housing, but a specially designed case that borrows elements from the Commodore 65.

The main differences to the previous version of the Elwro Junior were

  • Built in 720k 3.5" Disk-Drive
  • Default boot to CP/M
  • Color TV modulator
  • Support for 3 floppy disk drives

One of the biggest draw-back of this computer was the slower emulation for Spectrum Software: spectrum programs ran about 20% slower than on previous Elwro Juniors.

Overview of Elwro Junior Computers

From 1985 to 1990 Elwro produced the Elwro 800 Junior line of computers, meant for education. The polish department of education needed computers for the students. Many biggers schools had opted for ZX Spectrum, Timex or MSX. For smaller schools, the computer had to be cheap, ZX Spectrum compatible and easy to produce and repair.

The 800 Junior computers were produced using an existing case that was designed for the "Elwirka" toy piano. The elwro computers therefore have an odd feature: a sheet music stand that folds up to hold a paper with a music score.

I/O on the Elwro Junior

Elwro Junior computers were cheap, but well designed. It was ZX SPectrum compatible, but had better specifications than the Spectrum itself.

  • Joystick connector
  • SPectrum network connector
  • Composite Output
  • RGB Output
  • Tape connector
  • Junet network connector
  • Diskdrive connector (if controller installed)
  • Centronics Printer Port

JUNET was a serial bus network. The computers were daisy-chained; if you disconnected one computer, all computers further in the chain were disconnected from network. Connecting to network was performed by plugging 2-DIN plugs into the computer. Sockets are jumpered 1:1 inside. Network has 3 lines: Data, Clock and busy. The clock was set at 14MHz/256, with the master computer giving the clock to the rest; the data transfer rate is around 55kbit/sec The networking is done by 8521 USART or it's Soviet cousin, the KP580BB51A.

History of Elwro Computers

The Elwro company was established in February of 1959 in Wroclaw, Poland. The company's full name is The Wroclaw Electronic Works (Wroclawskie Zaklady Elektroniczne). The Elwro's first computer was the vacuum-tube based Odra 1001. This computer only reached the research stage and not mass produced. The next model was the Odra 1002 which replaced the vacuum tubes with transistors. The company also produced the tube-based UMC-1 from 1962 to 1965, 25 units were built.

By Elwro CPU U880D @3.5MHz (Z80 Clone) Memory 64K RAM, 24K ROM Sound 1 channel, 10 octaves Sprites none Display 32x24, 64x24 Text, 256x192 Graphics 8x2 colors Display Chip Sound Chip none CPU Class Z80 Developed by Elwro
Related Systems
Elwro Computers
Elwro  804 (Junior)
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