EMMA 02

COSMAC Elf 2000

  • 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

 

 

 

 

 

 

 

 

 

 

 

 

Video

The Cosmac Elf 2000 has 2 video options, the ’onboard’ CDP 1861 or the 80 Column Text Video Board running the intel 8275. Next to this also a Video Terminal like the DEC VT52 or a PC running terminal emulation can be connected.

CDP 1861

For details on the CDP 1861 please see the data sheets for this chip or the ’summary’ on the CDP 1861 page. The Elf 2000 controls the CDP 1861 via OUT 1 to switch the display off, OUT 2 to switch the display on and EF1 to indicate the display status.

The Elf 2000 firmware has a CDP 1861 test function, started via command TE PIX (This command can be given if a video terminal is connected to the Elf 2000). The test function uses the most common CDP 1861 resolution of 64 x 32 with interrupt routine entry point at @9072 and display memory at @9500-@95FF (ROM, showing the ‘famous’ enterprise picture).

The display status is an active low output signal occurring for a period of four horizontal cycles prior to the beginning and end of the 128 line display window. The signal is used by the firmware interrupt routine to indicate the last ’row’ of the display area.

Intel 8275

The 8275 retrieves characters from memory and displays them on a row by row basis. The 8275 has two row buffers. While one row buffer is being used for display, the other is being filled with the next row of characters to be displayed. The number of display characters per row and the number of character rows per frame are software programmable.

The 8275 requests DMA to fill the row buffer that is not being used for display. DMA burst length and spacing is programmable.

The 8275 displays character rows one line at a time. The number of lines per character row, the underline position, and blanking of top and bottom lines are programmable.

For additional details on the intel 8275 please see the data sheet.

The Elf 2000 controls the 8275 via, OUT 5 to write the command, INP 5 to read the status and OUT 1 / INP 1 to write / read a parameter. EF1 is connected to the vertical retrace.

The Elf 2000 uses the 8275 with 8x10 characters, 80 characters per row and 24 rows per screen.

Note that the video mode ’highlight’ is not supported in the HW and the invisible field atribute mode is not supported by the Elf 2000 firmware.