Microprocessor development board

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A Microprocessor Development Board is a printed circuit board containing a microprocessor and the minimal support logic needed for an engineer to become acquainted with the microprocessor on the board, and to learn do some elementary assembler programming on it. It also served for the producer of the microprocessor as a platform for testing their new chip.

It differs from a home computer by not having any logic above what is absolutely necessary to create a working system with an ability to enter and execute a machine language program, and evaluate the result. So normally all the things you would expect to have in a computer system designed for entertainment, such as a Video Display Controller, a sound-chip, and a keyboard usable for Basic, would not be available as a standard feature.

[edit] History

The reason for the existence of a development board was only to provide a system for learning to use a new microprocessor, not for entertainment. So everything superfluous was left out to keep costs down. Even an enclosure was not supplied, nor a power supply. This because the board would only be used in a "laboratory" environment so it did not need an enclosure, and the board could be powered by a typical bench power supply already available to an electronic engineer.

Microprocessor training development kits were not always produced by microprocessor manufacturers. Many systems that can be classified as microprocessor development kits were produced by third parties, one example is the Sinclair MK14, which was inspired by the official SC/MP development board from National Semiconductor, the "NS introkit".

Although these development boards were not designed for hobbyists, they were often bought by them because they were the earliest cheap microcomputer devices you could buy. They often added all kinds of expansions, such as more memory, a video interface etc. It was very popular to use (or write) an implementation of Tiny Basic. The most popular microprocessor board, the KIM-1, received the most attention from the hobby community, because it was much cheaper than most other development boards, and you could get more software for it (Tiny Basic, games, assemblers), and cheap expansion cards to add more memory or other functionality. Also much more articles were published in magazines like "Kilobaud Microcomputing" that described home-brew software and hardware for the KIM-1 you could copy than for other development boards.

[edit] Features

The most important feature of the microprocessor development board was the ROM based built-in machine language monitor, or "debugger" as it was also sometimes called. Often the name of the board was related to the name of this monitor program, for example the name of the monitor program of the KIM-1 was "Keyboard Input Monitor", because the ROM based software allowed entry of programs without the rows of cumbersome toggle switches that older systems used. The popular 6800 based systems often used a monitor with a name with the word "bug" for "debugger" in it, for example the popular "MIKBUG".

Input was normally done with a hexadecimal keyboard, using a machine language monitor program, and the display only consisted of a 7-segment display. Backup storage of written assembler programs was primitive, only a cassette type interface was typically provided, or the serial telex interface was used to read (or punch) a papertape.

Often the board has some kind to expansion connector that brought out all the necessary CPU signals, so that an engineer could build and test an experimental interface or other electronic device.

External interfaces on the bare board were often limited to an RS232 serial port, so a terminal, printer, or teletypewriter could be connected.

[edit] List of development boards

  • 8085AAT a 8085 microprocessor training unit from Paccom
  • CDP18S020 evaluation board for the RCA CDP1802 microprocessor
  • EVK 300 6800 single board from American Microsystems (AMI)
  • Explorer/85 expandable learning system based on the 8085, by Netronics's research and development ltd.
  • ITT experimenter used switches and LEDs, and an intel 8080
  • KIM-1 the development board for the MOS Technology/Rockwell/Synertek 6502 microprocessor. The name KIM is short for "keyboard input monitor"
    • SYM-1 a slightly improved KIM-1 with better software, more memory, and I/O. Also known as the VIM
    • AIM-65 an improved KIM-1 with an alphanumerical LED display, and a built-in printer.
    • The KIM-1 also lead to some unofficial copies, such as the super-KIM and the Junior-computer from the magazine Elektor, and the MCS Alpha 1
  • LC 80 by Robotron
  • MAXBOARD development board for the Motorola 6802.
  • MEK6800D2 the official development board for the Motorola 6800 microprocessor. The name of the monitor software was MIKBUG
  • MicroChroma 68 color graphics kit. Developed by Motorola to demonstrate their new 6847 video display processor. The monitor software was called TVBUG
  • Motorola excorcisor development system (rack based) for the Motorola 6809
  • Microprofessor I (MPF-1) Z80 development and training system by Acer
  • NS introkit by National Semiconductor featuring the SC/MP, the predecessor to the Sinclair MK14
  • NRI microcomputer, a system developed to teach computer courses by McGraw-Hill and the National Radio InstituteI (NRI)
  • MK14 Trainings system for the SC/MP microprocessor from Sinclair Research Ltd.
  • SDK-85 Intels development board for their 8085 microprocessor
  • SDK-86 Intels development board for their 8086 microprocessor
  • Siemens Microset-8080 boxed system based on a 8080.
  • RCA Cosmac Super Elf by RCA . a 1802 learning system with an RCA 1861 Video Display Controller.
  • TK-80 the deveopment board for NEC's clone of Intel's i8080, the μPD 8080A
  • TM 990/100M evaluation board for the Texas Instruments TMS9900
  • TM 990/180M evaluation board for the Texas Instruments TMS9800
  • XPO-1 Texas Instruments development system for the PPS-4/1 line of microcontrollers