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- COSMAC_ELF abstract "The COSMAC ELF was an RCA 1802 microprocessor-based computer based on a series of construction articles in Popular Electronics magazine in 1976 and 1977. Through the back pages of electronics magazines, both Netronics and Quest Electronics offered low-priced kits that were based on this design. The system was a very early personal computer. It was operated without built-in ROMs and programs were entered directly with help of the CPU integrated DMA.It featured two hexadecimal LED displays for output and a set of toggle switches or a hexadecimal keypad for input.The base configuration had 256 bytes of RAM, but expansion boards could raise that to 4096 or 32,768 bytes of RAM.The original ELF design used a crystal with a frequency in the range of 1 to 2 MHz with the 1802's built in oscillator circuit.A simple circuit used the DMA feature of the 1802 to permit entry of programs and data into RAM through the toggle switches. Entering a byte via the toggle switches and pressing the \"input\" button would enter a byte into RAM and display it on the pair of hex LEDs, then advance the DMA counter to the next location. A \"memory protect\" switch could be used to disable memory alteration. If an error was made in program entry, it could be corrected by turning on memory protect, turning off load mode (thus resetting the program counter to zero), turning on load mode, and pressing \"input\" to advance to the address of the incorrect data. After turning off memory protect, the correct value could be entered.The fourth article of the series presented modifications to use a companion RCA 1861 “PIXIE” video generator IC. The PIXIE required a 1.76 MHz clock, and since that was an uncommon crystal frequency, usually a readily available 3.579545 MHz colorburst crystal was instead used in a separate oscillator circuit with a divide-by-two circuit to drive the clock inputs of both the microprocessor and PIXIE. Monochrome video output (with timing roughly approximating NTSC standard) could be generated using DMA operations interleaved with carefully arranged 1802 opcodes. The maximum resolution by the 1861 was 64h by 128v pixels. By changing the placement of instructions in the video display subroutine, pixel rows could be repeated to obtain lower resolutions, allowing the video display to be used even with 256 bytes of RAM.A one-bit output from the microprocessor, the Q line, could be driven by software to produce sounds through an attached speaker or to save programs in RAM to a cassette recorder. Branch instructions in the 1802 instruction set could read the state of the EF1 through EF4 input lines, which were used to read the I keypad button and programs from the cassette recorder, along with input from peripherals such as a light pen.".
- COSMAC_ELF cpu RCA_1802.
- COSMAC_ELF thumbnail COSMAC_ELF_CHM.jpg?width=300.
- COSMAC_ELF wikiPageExternalLink simelf.
- COSMAC_ELF wikiPageExternalLink www.emma02.hobby-site.com.
- COSMAC_ELF wikiPageExternalLink memship.html.
- COSMAC_ELF wikiPageExternalLink Elf2K.htm.
- COSMAC_ELF wikiPageID "996155".
- COSMAC_ELF wikiPageLength "6907".
- COSMAC_ELF wikiPageOutDegree "31".
- COSMAC_ELF wikiPageRevisionID "694980348".
- COSMAC_ELF wikiPageWikiLink BASIC.
- COSMAC_ELF wikiPageWikiLink BIOS.
- COSMAC_ELF wikiPageWikiLink Byte.
- COSMAC_ELF wikiPageWikiLink COSMAC_VIP.
- COSMAC_ELF wikiPageWikiLink Category:Early_microcomputers.
- COSMAC_ELF wikiPageWikiLink Central_processing_unit.
- COSMAC_ELF wikiPageWikiLink Colorburst.
- COSMAC_ELF wikiPageWikiLink Disk_operating_system.
- COSMAC_ELF wikiPageWikiLink Forth_(programming_language).
- COSMAC_ELF wikiPageWikiLink Hexadecimal.
- COSMAC_ELF wikiPageWikiLink Home_computer_remake.
- COSMAC_ELF wikiPageWikiLink Keypad.
- COSMAC_ELF wikiPageWikiLink Light-emitting_diode.
- COSMAC_ELF wikiPageWikiLink Magazine.
- COSMAC_ELF wikiPageWikiLink Microprocessor.
- COSMAC_ELF wikiPageWikiLink Netronics.
- COSMAC_ELF wikiPageWikiLink Nuts_and_Volts.
- COSMAC_ELF wikiPageWikiLink Personal_computer.
- COSMAC_ELF wikiPageWikiLink Popular_Electronics.
- COSMAC_ELF wikiPageWikiLink Quest_Electronics.
- COSMAC_ELF wikiPageWikiLink RCA.
- COSMAC_ELF wikiPageWikiLink RCA_1802.
- COSMAC_ELF wikiPageWikiLink Random-access_memory.
- COSMAC_ELF wikiPageWikiLink Read-only_memory.
- COSMAC_ELF wikiPageWikiLink Switch.
- COSMAC_ELF wikiPageWikiLink Video_display_controller.
- COSMAC_ELF wikiPageWikiLink File:Early_Personal_Computers.jpg.
- COSMAC_ELF wikiPageWikiLinkText "COSMAC ELF".
- COSMAC_ELF caption "COSMAC ELF with PIXIE Graphics Display".
- COSMAC_ELF cpu RCA_1802.
- COSMAC_ELF memory "256".
- COSMAC_ELF name "COSMAC ELF".
- COSMAC_ELF wikiPageUsesTemplate Template:Cite_journal.
- COSMAC_ELF wikiPageUsesTemplate Template:Infobox_information_appliance.
- COSMAC_ELF wikiPageUsesTemplate Template:Reflist.
- COSMAC_ELF wikiPageUsesTemplate Template:Start_date_and_age.
- COSMAC_ELF subject Category:Early_microcomputers.
- COSMAC_ELF hypernym RCA.
- COSMAC_ELF type Album.
- COSMAC_ELF type Device.
- COSMAC_ELF type InformationAppliance.
- COSMAC_ELF type Computer.
- COSMAC_ELF type Microcomputer.
- COSMAC_ELF type Thing.
- COSMAC_ELF type Q1067263.
- COSMAC_ELF comment "The COSMAC ELF was an RCA 1802 microprocessor-based computer based on a series of construction articles in Popular Electronics magazine in 1976 and 1977. Through the back pages of electronics magazines, both Netronics and Quest Electronics offered low-priced kits that were based on this design. The system was a very early personal computer.".
- COSMAC_ELF label "COSMAC ELF".
- COSMAC_ELF sameAs Q5013511.
- COSMAC_ELF sameAs m.03xqpr.
- COSMAC_ELF sameAs Q5013511.
- COSMAC_ELF wasDerivedFrom COSMAC_ELF?oldid=694980348.
- COSMAC_ELF depiction COSMAC_ELF_CHM.jpg.
- COSMAC_ELF isPrimaryTopicOf COSMAC_ELF.
- COSMAC_ELF name "COSMAC ELF".