# ELF II

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{{Short description|1978 microcomputer trainer kit by RCA}}
{{Infobox information appliance
| name         = ELF II
| logo         = 
| image        = ElF II Computer.jpg
| caption      = 
| aka          = 
| developer    = 
| manufacturer = Netronics
| family       = 
| type         = Hobbyist computer
| generation   = 
| lifespan     = 
| discontinued = 
| media        = 
| os           = Monitor ROM
| power        = external power supply
| system_on_chip          = 
| cpu          = 8-bit [RCA 1802](/source/RCA_1802)
| memory       = 256 bytes to 64&nbsp;KB via 4&nbsp;KB or 16&nbsp;KB memory expansion cards
| storage      = Cassette Tape
| memory_card  = 4&nbsp;KB or 16&nbsp;KB [static RAM](/source/static_RAM) memory cards
| display      = none
| graphics     = 64x32 pixels, monochrome, [NTSC](/source/NTSC) TV output
| sound        = 
| input        = 
| controllers  = 
| camera       = none
| touchpad     = HEX keypad
| connectivity = 
| platform     = 
| dimensions   = 
| weight       = 
| compatibility= 
| predecessor  = 
| successor    = 
| related      = 
| website      = <!--{{URL|example.org}}-->
| release_date  = {{Start date and age|1978}}
| price        = 
| units_sold    = 
| units_shipped = 
| online_services      = 
| top_game      = 
}}
The Netronics '''ELF II''' was an early [microcomputer](/source/microcomputer) trainer kit featuring the [RCA 1802](/source/RCA_1802) microprocessor, 256 bytes of [RAM](/source/Random_Access_Memory), [DMA](/source/Direct_memory_access)-based bitmap graphics, [hexadecimal](/source/hexadecimal) keypad, two-digit [hexadecimal](/source/hexadecimal) [LED](/source/LED) display, a single "Q" LED, and 5 expansion slots. The system was developed and sold by Netronics Research and Development Limited in [New Milford, CT](/source/New_Milford%2C_CT), USA.<ref>{{Cite web|url=http://www.vcfed.org/forum/attachment.php?attachmentid=8240&d=1331861424|title=Image of Mailing Box with Address Label|last=|first=|date=|website=VCFED.org|publisher=|access-date=27 June 2016}}</ref>

== Hardware ==
Available hardware accessories included:
* The "Giant Board" ([ROM](/source/read-only_memory) monitor, serial and parallel I/O, [Cassette](/source/Compact_Cassette) interface)
* 4&nbsp;KB and 16&nbsp;KB ([static](/source/static_RAM)) RAM boards
* Low-resolution color [graphics board](/source/graphics_board)
* "Full BASIC" board with [BASIC](/source/BASIC) preloaded in [ROM](/source/Read-only_memory) chips
* [EPROM](/source/EPROM) burner board
* External power supply
* Attractive, heavy-duty metal cases for the CPU and power supply

==Software==
Available software included:
* [Tiny BASIC](/source/Tiny_BASIC) ([integer](/source/integer) [BASIC interpreter](/source/BASIC_interpreter))<ref>{{cite web |last1=Pittman |first1=Tom |title=Tiny Basic Info |url=http://www.ittybittycomputers.com/IttyBitty/TinyBasic/ |website=Itty Bitty Computers |accessdate=4 August 2020}}</ref>
* Text Editor
* Full BASIC ([floating point](/source/floating_point) [BASIC](/source/BASIC) [interpreter](/source/interpreter_(computing)) using [Reverse Polish Notation](/source/Reverse_Polish_Notation))

==Notable features==
* Unlike similar "bare circuit card" trainer/experimenter computers of the day, the ELF II could be easily expanded thanks to its built-in [bus](/source/Bus_(computing)).
* Memory mapped TV graphics was provided in the base kit by the [CDP1861](/source/RCA_CDP1861) "Pixie-Graphics" chip. Pixels were large. With unexpanded 256 byte memory, the [interrupt](/source/interrupt) routine needed to service the chip showed on the screen.
* The "Full BASIC" ROM card provided an [RPN](/source/Reverse_Polish_notation) calculator chip as a simple and low-cost [math coprocessor](/source/math_coprocessor).  As a result, floating point operations were an order of magnitude faster than what was possible in software. However, the BASIC syntax for math was non-standard as it used postfix RPN (see code example below). Historically, this was also the heyday of [Hewlett-Packard](/source/Hewlett-Packard) calculators, so it was a fair bet that any technically-minded person willing to assemble a computer either already knew RPN or could easily learn it and adapt.<syntaxhighlight lang="Qbasic">
10 REM This program will print the number 30
20 A=10,B=20
30 C=A#B+
40 PRINT C
50 END
</syntaxhighlight> In the code above, the "#" symbol is equivalent to the "Enter" key on a RPN calculator.

==Netronics video terminal==
Netronics also offered:
* An [ASCII](/source/ASCII) keyboard kit
* Heavy-duty metal keyboard case
* Video terminal card kit (monochrome text, 16 lines by 64 characters, upper & lower case)
The keyboard could be used alone to generate ASCII parallel codes.  The video terminal card fits underneath the keyboard in the optional case to form a stand-alone video terminal sending and receiving serial ASCII. Either configuration could be interfaced to the ELF II through the Giant Board.  The terminal kits were also marketed independently of the ELF II.

== The name ==
The ELF part of the name came from an earlier machine called the "[COSMAC Elf](/source/COSMAC_Elf)", published as a construction project in [Popular Electronics](/source/Popular_Electronics) magazine. Improvements on its predecessor included an etched [PCB](/source/PCBoard), a hexadecimal keypad instead of [toggle switch](/source/toggle_switch)es for program entry, the [RCA CDP1861](/source/RCA_CDP1861) Pixie-graphics chip, and the 5 slot 86-line bus for expansion cards.

==See also==
*[COSMAC Elf](/source/COSMAC_Elf)
*RCA [COSMAC VIP](/source/COSMAC_VIP)
*Quest SuperELF
*[RCA 1802](/source/RCA_1802) microprocessor
*[Early Microcomputers](/source/Early_Microcomputers)
*Competing [6502](/source/MOS_6502) microprocessor based trainers [KIM-1](/source/KIM-1) and Rockwell [AIM-65](/source/AIM-65)
*[8080](/source/Intel_8080) Based machines: MITS [Altair 8800](/source/Altair_8800) and [IMSAI 8080](/source/IMSAI_8080)
*[RCA Studio II](/source/RCA_Studio_II)

==References==
{{Reflist}}

== External links ==
* {{cite web
 | url = http://www.cosmacelf.com/links.html
 | title = COSMAC ELF
}}

Category:Early microcomputers
Category:RCA computers
Category:1802-based computers
Category:Computer-related introductions in 1978

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Adapted from the Wikipedia article [ELF II](https://en.wikipedia.org/wiki/ELF_II) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/ELF_II?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.