EMMA 02

Netronics Elf II

  • Home
  • CDP18S020
    • General Information
    • I/O Map
  • COMIX-35
  • COMX-35
    • General Information
    • F&M
    • Did You Know...?
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Cassette
    • Expansion Box
    • Disk
    • Printers
    • Thermal
    • PL-80
    • 32K RAM
    • 80 Column
    • F&M EPROM
    • F&M Joy Card
    • Super Board
    • COMX BASIC V1.00
  • COSMAC Elf
    • General Information
    • I/O Map
    • Front Panels
  • COSMAC Elf 2000
    • General Information
    • I/O Map
    • Memory
    • Video
  • COSMAC Microtutor
    • General Information
    • I/O Map
  • COSMAC Microtutor II
    • General Information
    • I/O Map
  • COSMAC Vip
    • General Information
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Cassette
    • STK
    • Chip-8 and 8X
    • Test-Word
    • Floating Point BASIC 2.2
  • COSMAC Vip II
    • General Information
    • I/O Map
    • Floating Point BASIC 2.2
  • Cidelsa
    • General Information
    • I/O Map
    • Memory
    • Video
    • Sound
  • Conic
  • Cosmicos
    • General Information
    • I/O Map
    • Front Panels
    • Mops & Hexmops
    • ASCII Monitor
    • HEX Monitor & UT4
  • CyberVision
  • ETI-660
  • FRED 1
    • General Information
    • I/O Map
    • Cassette
    • CARDTRAN Syntax
  • FRED 1.5
    • General Information
    • I/O Map
    • Cassette
    • Cassette
    • FPL-2
    • FPL-4
    • FEL-1
  • HEC1802
  • HUG1802
    • General Information
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Cassette
    • Chip-8 ETI-660
  • Infinite UC1800
    • General Information
    • I/O Map
  • JVIP
  • Macbug
  • Membership Card
    • General Information
    • I/O Map
  • Netronics Elf II
    • General Information
    • I/O Map
    • Front Panels
    • Keyboard
    • Giant Board
    • BASIC/Math
  • Oscom Nano
    • General Information
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Casette
  • Pecom 32 and 64
    • General Information
    • Software
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Casette
    • Pecom 32 BASIC
    • Pecom 64 BASIC 1.0 & 4.0
  • Pico/Elf V2
    • General Information
    • I/O Map
  • Quest Super Elf
    • General Information
    • I/O Map
  • RCA Game System
  • RCA Microboard
    • General Information
    • I/O Map
  • RCA MS2000
    • General Information
    • I/O Map
  • RCA MCDS
    • General Information
    • I/O Map
  • RCA Studio II
    • General Information
    • I/O Map
    • Memory
    • Video
    • Keyboard
    • ST2
  • RCA Studio III
    • General Information
    • I/O Map
    • Memory
    • Video
    • Keyboard
  • RCA Studio IV
    • General Information
    • I/O Map
    • Memory
    • Video
    • Keyboard
    • ST4 Syntax
  • RCA Video Coin
    • General Information
    • I/O Map
    • Memory
    • GPL-A (2K RAM)
    • GPL-A (2K ROM)
    • GPL-2
    • GPL-3
    • GPL-4
  • SBC1802
  • Studio 2020
  • Telmac 1800
    • General Information
    • I/O Map
    • Memory
    • Video
    • Keyboard
    • Cassette
  • Telmac 2000
    • General Information
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Cassette
  • Telmac TMC-600
    • General Information
    • Software
    • I/O Map
    • Memory
    • Video
    • Sound
    • Keyboard
    • Cassette
    • Telmac SBASIC v24.3
  • VELF
    • General Information
    • I/O Map
    • BIOS
    • Video
    • Keyboard
  • VIP2K MC
    • General Information
    • I/O Map
    • Memory
    • Video
    • Chip 8
  • VIS1802
  • VT1802
  • Visicom COM-100
    • General Information
    • I/O Map
    • Memory
    • Video
    • Keyboard

 

 

 

 

 

 

 

 

 

 

 

 

Keyboard

The Netronics Elf II uses a 74C923, 20 Key Encoder in combination with a 74C173 Quad D Flip-Flop to control the hexadecimal keypad. The flip-flop is used to 'store' the second last key pressed and the key encoder itself 'stores' the last key pressed. This is shown in the keyboard circuit below, where 'TO A3' is connected via a quad switch (CD4016) to D0-D3 and 'TO A4' via another quad switch to D4-D7. The quad switches are controlled both via INP4 and/or the LOAD switch.

So at every INP4 the last 2 hexadecimal keys pressed are received, the same is valid in LOAD mode when the 'IN' button is pressed.