Scor­pio News


October–December 1988 – Volume 2. Issue 4.

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Features of the Z180 processor

  • Z80 compatible CPU running at up to 8MHz clock
  • Memory Mapping Unit giving access to a 1MByte address space
  • Two vectored interrupt inputs in addition to the standard Z80 NMI mid INT facilities
  • Two DMA channels to provide fast memory to memory, and memory to/from I/O data transfers
  • Two full duplex asynchronous serial communication interfaces
  • One synchronous, or clocked, high speed serial interface
  • Two programmable counter/​timer channels
  • Illegal opcode software interrupt (trap)
  • Enhanced Z80 instruction set

Features of the NE898 board

  • Z180 with a link selectable 4 or 8MHz clock, giving access to all the above facilities
  • GM813 compatibility in all respects except for the serial interfaces
  • 80-BUS compatibility, running the bus at the full 8MHz
  • 256Kbyte dynamic RAM (120 nanosecond)
  • 32 Kbyte Monitor/​Boot PROM
  • Five additional byte-wide sockets each accepting 32Kbyte ROM or static RAM, with link selectable battery backup
  • An SPCT chip offering, in-one package, the following fully Z80 compatible 8MHz devices:
          Z80 PIO – two parallel channels
          Z80 CTC – four programmable counter/​timer channels
          Z80 SIO – two full duplex serial ports
  • Battery backed, 58274 real time clock chip
  • P-Bus parallel interface to allow connection to the range of Newburn Industrial I/O modules
  • LCD interface capable of driving standard alphanumeric displays
  • Multi-processor facilities – two NE898s can operate in one backplane, sharing peripherals and the work-load
  • Watch-dog timer to allow recovery or detection of system crash or hang-up situations

The decision to run the bus at 8MHz is a brave one. Although the possibility had been recognised in the 80-BUS specification by inclusion of the AUX CLK line, I believe this is the first time it has been done commercially. Newburn claim to have tested many of the existing boards with the NE898 at 8MHz, and have had no serious problems. The NE898 is also available without the eight DRAM chips at a price of £399. This option will appeal to those wishing to run the system on static RAM, or who might wish to populate the DRAM sockets themselves.

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