ND-120 CPU

From NDWiki
Revision as of 03:51, 22 December 2023 by RHansen (talk | contribs) (First summary of the great ND-120/CX CPU)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Overview

The ND-120/CX CPU was a complete reimplementation on an LSI chip (The so-called Delilah chip).

The designers was Lasse Bockelie and Chris Cherrington.


Introduction

The ND-120/CX is an improvement over the ND-110_CPU in a number of areas.

  • Finally, the CPU board has an UART with RS-232 interface. Up until now all the ND CPU's used current-loop interface.
  • Onboard memory up to 6MB.
  • The ND-120/CX CPU is a high-speed version (approximately 1.9 times faster) of the ND-110/CX CPU.
  • The ND-120 CPU is upwards compatible with the ND-110 and ND-100 CPUs.
  • The CPU
    • In the ND-110 the CPU is constructed from three VLSI gate arrays (RMIC, RMAC and BUFALU).
    • In the ND-120 the CPU is constructed from one big VLSI gate array, the CPU Gate Array (CGA)
      • The ND-120 has a helper chip, the DELILAH Decoding Logic Gate Array (DGA). It was produced by NEC.
    • There is an onboard 68705U3 CPU/Microcontroller on the CPU board, for Panel Control and real-time clock.
  • Cycle Control:
    • The cycle controller, which defines the timing sequence in executing microinstructions, operates differently in the ND-120 compared to the ND-110.
  • Microcache:
    • The ND-110 has a 2K long instruction cache and microcache address area occupying the top 2K in control store.
    • The ND-120, in contrast, has a 1K long instruction cache and microcache address area occupying the top 1K in control store.
    • In ND-120, the address range 6—7K is not required for microcache, and may be used as a further 1K of extension area.

Print versions

  • 3202 - The development phase used board revisions A, B and C
  • 3202 - The final revision was D. The design documents dates this revision to 5/10/1987.

Macrocode

There doesnt seem to be any new macrocode opcodes in the ND-120/CX vs the ND-110/CX.

Microcode

The microcode is very similar to the microcode in the ND-110 except a few changes. And most of the changes seems to be related to the change of the UART.

Summary:

  • For the ND-110, bits 21-27 of the microinstruction word are inverted after assembly. This has been fixed for the ND-120.
  • Bit 21 has been renamed to DLY from DELAY to accord with revised timing delay function.
  • Bits 32-36 (Command field):
    • Changed Command 5
    • New Command 36.2 : LCS (Load Command Store) - The whole of the control store is loaded from Control Store PROM to Control Store RAM
    • New Command 36.3 : XSLOW - In ND-120, force current microcycle to the maximum length of time (435.2ns). This is used for very slow I/O devices e.g. the UART
    • Changed Command 06,0
      • In ND-110, 'TBSTR' - Transmit Data Strobe command to the UART on the PCU card
      • In ND-120, 'spare'
    • Changed Command 10 SLOW (Command a "slow" microcycle)
      • In ND-110 a slow microcycle is 256ns
      • In ND-120 a slow microcycle is a minimum (no wait states) of 204.8ns
  • Bits 37-41 (IDBS - Internal Data Bus Source)
    • IDBS 34 - In ND-110 this was 'JMPA', in ND-120 this is a 'spare'
    • IDBS 36 - In ND-110 this was a 'spare', in ND-120 this is 'PICMASK" (Read PIC mask register)
    • IDBS 37 - In ND-110 this was a 'spare', in ND-120 this is 'UART' (For reading from UART. See also command decode 5.x CEUART)


For more details check out the "ND-06.031.1 EN ND-110 and ND-120 Microprogrammer's Guide" document.[1]

A scanned source of the the Microcode and a dump of the EPROM's from an ND-120/CX CPU version L is available

Design documents


There is also a copy of the scanned design document PDF's at norsk-data.com:


Training videos

  • ND-120 - DELILAH - Hardware Introduction - Part 1 of 2 YouTube

The ND-120 CPU was a complete reimplementation on an LSI chip (The so-called Delilah chip). This is part 1 of 2 - with Lasse Bockelie from February 1987

  • ND-120 - DELILAH - Hardware Introduction - Part 2 of 2 YouTube

The ND-120 CPU was a complete reimplementation on an LSI chip (The so-called Delilah chip). This is part 2 of 2 - with Chris Cherrington from February 1987