BraiLab Plus-77 target computer

Education for the blind and visually impaired

 A product widespread throughout Europe

Hungarian Academy of Sciences Central Research Institute of Physics

Structure

Central unit

Byte-organized machine (8 bpB

• controller: Zilog Z80 microprocessor, clock speed: 4 MHz
• main store:
  • 256 KB DRAM
  • 4 KB SRAM
  • 16 KB EPROM
  • EPROM character generator

Periphery

• backup: tape recorder
• external devices:
  • WD2793 floppy disk, 256 KB
  • I8251 PUSHART and MEA-8000 speech synthesizer
• interfaces:
  • two Z80 programmable input/output ( PIO )
  • standard serial and parallel connections
  • monochrome video output (for CRT display)
  • headphone jack
  • outputs for connecting two sound modules

The machine was made in a portable design, the floppy disk drive was in a separate box together with the power supply. Total weight ∼ 5 kg + CRT display.

Operation

Of the 256 KB of DRAM, 180 KB acts as a disk, under the control of the operating system; the 4 KB of SRAM stores the characters displayed on the screen (25 lines, 80 chpl)

The two PIOs automatically control the operation of external devices (system clock, interrupt handling, serial data transfer scheduling)

The keyboard, which has been expanded by 5 keys, has 4 arrow keys to help blind users navigate the screen, and the highlighted Escape key makes it easier to correct errors.

The sound output of the MEA-8000 formant synthesizer is connected to a common speaker with a keystroke beep

Program set

• operating system: CP/M
• compilers:
  • extended BASIC
  • C

Voice generator and text-to-speech converter with intonation enhancement

Historical curiosities

A unique aid for the education of the blind at European level

Resources

Detailed historical and technical description: Brailab talking computer