Yamaha YIS-805/128R2
This page was last modified 08:22, 27 February 2018 by Gdx. Based on work by Mars2000you.

Contents

Description

Computer

The Yamaha YIS-805/128R2 is the adaptation of the YIS-805/128 computer for Soviet Union. It has by default one disk drive, but there's a location planned for the addition of a second disk drive. The expansion bus slot at the back has been removed. This machine was not sold in shops and could only be used in schools. The "КУВТ2" logo is the abbreviation of "Комплект учебной вычислительной техники 2" and means "Class of Teaching Computing Equipment 2".

This computer has a Russian keyboard, it was generally used by the teacher while the students had a YIS-503IIIR without any drive.

Brand Yamaha
Type YIS-805/128R2
Year 1986
RAM 128kB in slot 3-2
VRAM 128kB
Media MSX cartridges, DD floppy disks
Video Yamaha V9938
Audio PSG (YM2149 integrated in MSX-Engine S1985)
Chipset Yamaha S1985
Extras 1 or 2 720kB 3,5" floppy disk drives, Network unit + switch + Network BASIC, THE PAINTER (graphic tool)

Serial I/O Unit

The communication between MSX computers is actually controlled by a sophisticasted interface build around the YM3802 chip (MIDI Communication & Service Controller). This communication system is completely incompatible with the RS-232C system used on the MSX1 YIS-503IIR computer.

The Yamaha Serial I/O Unit (CB55448) is placed in the side module slot, it has 2 specific serial ports and an internal DIP switch with 4 configurable bits that define the number of student machine (1 - 15). Setting DIP to 0 makes the machine a teacher's machine. This module is used to create an MSX Network.

In this MSX-Network, up to 8 student machines are connected to a teacher machine using one of the floppy disk drives for centralised file storage.

Firmware

When booting, the network is automatically initialized, you can switch it off by CALL NETEND or _NETE and eventually switch it on again with CALL NETINIT or _NETI (all CALL commands can be shortened to 3-4 letters and a space is not required after the underscore).

The network firmware can be disabled by pressing DEL key while booting. It is recommended to disable it for playing games, this to avoid eventual incompatibility or for using the machine as a standard MSX2. However, some games were adapted to play them in network.

Another firmware is included in this computer, it's THE PAINTER, a graphic utility in screen 5. From MSX-BASIC, this firmware can be launched with CALL PAINT or _PAINT, but you can also boot the computer while pressing the SPACE key to directly start this utility.

Pictures

Computer

Yamaha YIS/805-128R2
Yamaha YIS/805-128R2 keyboard
Yamaha YIS/805-128R2
Yamaha YIS/805-128R2 front
Yamaha YIS/805-128R2 PCB
Yamaha YIS/805-128R2 back
Yamaha YIS/805-128R2 right side

Serial I/O Unit

Yamaha Serial I/O Unit
Yamaha Serial I/O Unit underside
Yamaha Serial I/O Unit PCB
Yamaha Serial I/O Unit external side

Firmware

The Painter
The Painter

Specifications

The YIS-805/128R2 is a MSX2 with a Z80A from Sharp (LH0080A) and an MSX-Engine S1985 from Yamaha. Floppy Disk Controller chip is the 8876.

This model can be easily upgraded internally to 256kB RAM.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3-0 Slot 3-1 Slot 3-2 Slot 3-3
Bank C000h~FFFFh Cartridge
Slot 1
Cartridge
Slot 2
Painter
ROM
128kB
Memory
Mapper
Module
Slot
Bank 8000h~BFFFh
Bank 4000h~7FFFh Main-ROM Disk-ROM
Bank 0000h~3FFFh Sub-ROM
  • By default the Module Slot contains a serial network interface module from 4000-BFFF

Connections

  • RGB output
  • Analog sound & Composite video (monochrome NTSC)
  • Keyboard connector
  • Tape recorder connector
  • Centronics compatible Parallel port for a printer
  • 2 general connectors (joysticks, mouse, paddle controllers, ...)
  • 2 cartridge slots
  • 1 module slot (on right side, 60 pin connector)
  • 2 serial port connectors (on the Serial I/O Unit)
  • Two AC power plugs