K1520 bus

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The K1520 bus was an early computer bus, created by VEB Robotron in 1980 and specified in TGL 37271/01. It was the predominant computer bus architecture of microcomputer-sized systems of East Germany, whose industry relied heavily on the U880 microprocessor, a clone of the Zilog Z80.

Among the large number of boards developed using the standard were

• CPU modules
• RAM modules
• graphics cards
• magnetic tape controllers
• Floppy disk controllers

It was originally intended to be used to connect boards to backplanes, as in the

• A 5120 office computer
• A 5130 office computer
• Poly-Play arcade cabinet

but was also used as an extension bus for computers that featured a main board

• KC 85/2, KC85/3, KC85/4
  • 2 internal slots for extension cartridges and one back-side connector
• D002
  • expansion unit for 4 additional extension cartridges
• D004
  • floppy controller subsystem for KC95 based systems. 2 internal cartridge slots
• PC 1715
  • 2 internal slots, one being occupied by the standard issue floppy disk controller
• A 5105 (not produced in significant quantities)
• KC 87 (a.k.a. z9001 or KC85/1)
• Z1013
• KC compact (not produced in meaningful quantities)

The bus had 58 pins and was commonly physically represented by a two-row connector with 29 pins each.

The following signals and connections were used:

• DB0 ... DB7 (bidirectional data bus)
• AB0 ... AB15 (address bus)
• /MREQ, /IORQ, /RD, /WR, /RFSH, /M1, /WAIT, /HALT, /INT, /NMI, /BUSRQ, /RESET (Z80 control signals)
• /BAI, /BOA (/BUSACK priority chain)
• /IEI, IEO (interrupt enable priority chain)
• /IODI, /MEMDI, /RDY
• clock
• +5V
• -5V
• +12V
• ground

See also

• S-100 bus

References

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