--- title: RCA Cosmac Microtutor categories: - Computers params: name: Cosmac Microtutor image: /media/museum/photos/rca_cosmac_microtutor_1s.jpg company: /companies/rca company_name: RCA tabs: - photos - links photos: - title: SYSTEM EXPLAINED subtitle: '' text: |- 1 - 256 byte memory board\ 2 - micro-processor board\ 3 - clock speed adjustment\ 4 - clock capacitor\ 5 - NAND gates\ 6 - NOR gates\ 7 - flip flop\ 8 - LOAD switch\ 9 - IN button\ 10 - data switches\ 11 - START button\ 12 - CLEAR button\ 13 - 2 characters LED display (hexadecimal)\ 14 - converters and drivers for LED display\ 15 - 5V DC regulator Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_explained.jpg - title: MAIN BOARD subtitle: '' text: Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_1.jpg - title: COMPLETE SYSTEM WITH BOARDS INSERTED subtitle: '' text: Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_front_1.jpg - title: REAR subtitle: '' text: Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_rear.jpg - title: 256 BYTES MEMORY BOARD subtitle: '' text: Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_memory_board.jpg - title: MICROPROCESSOR BOARD (RCA CDP1801) subtitle: '' text: Thanks to Paul H. Tarver for this picture image: /media/museum/photos/rca_cosmac_microtutor_cpu_board.jpg - title: MICROTUTOR II subtitle: '' text: |- Almost the same computer but with a RCA CDP-1802 micro-processor integrated into the main board Thanks to [www.decodesystems.com](http://www.decodesystems.com) for the picture image: /media/museum/photos/rca_microtuto2_detail.jpg - title: MICROTUTOR II MANUAL subtitle: '' text: '' image: /media/museum/photos/rca_microtuto2_manual.jpg links: - title: Detailed article url: http://www.decodesystems.com/cosmac/computer-readout-ee-76nov.html text: column which appeared in the November-December 1976 issue of Elementary Electronics magazine - title: www.decodesystems.com url: http://www.decodesystems.com/cosmac/#microtutor2 text: Some info about 1802 based systems, inlcuding Microtutor II - title: Yahoo Groups - Cosmac Elf and 1802 based computers url: http://groups.yahoo.com/group/cosmacelf/ text: discussion group dedicated to RCA 1802 based micro computers comments: - author: Mario (Switzerland) date: Sunday 14th February 2021 text: '@Juan Suarez: yes, I''''m interested. Can you please send me a message to diverses ( at ) inbox ( dot ) com? Thank you, Mario' - author: Juan Suarez (Brazil) date: Sunday 7th June 2020 text: I both microtutor I and II with Manual if. You need more information please let me know. My Father worked many years for RCA - author: Mike Dalgleish (UK) date: Monday 24th July 2017 text: I''m interested in finding a microtutor. If you have one please $ me a line on md @ md46 . com oc_id: 1255 source: url: https://web.archive.org/web/20230603010019/http://www.old-computers.com/museum/computer.asp?c=1255 date: '2023-06-03' --- The Microtutor, manufactured in 1976, was used to educate engineers and others on how to program microprocessors. The unit is fully self-contained with the exception of the 9-volt power converter which plugs into the back of the unit. A clear plexiglass bottom allows the user to see all of the soldering done on the underside of the main board. The chips are all labelled both on the chip and on the board itself. There are three slots in the back labelled M,P,E. The M slot (M for Memory) allows the insertion of a card containing 256 bytes of memory. The P slot (P for Processor) allows the insertion of a processor card (here RCA CDP1801). The third slot labelled 'E' is for expansion and allows the user to create custom cards for controlling other devices. Microtutor is an 8-bit computer whose heart is the RCA CDP1801 microprocessor. It's made up of two plug-in ICs; the control IC and the register IC, both of which are mounted on the same plug-in card. RCA also proposed a CDP1802 which could handle more instructions than the 1801, and is on a single chip, but the basics of the 1801 and 1802 are the same. The control chip of the 1801 receives control signals from the clock and in turn controls the movemement of instructions and data through the register chip and into the RAM. There are 256 memory locations available in Microtutor although an 1801 can address up to 65,536 locations. There are four control switches and eight data switches. Let's look at the four control switches: Clear, Start, Load, and In. The Clear button returns the microprocessor to the first instruction of your program and lets it sit there. The Start button begins execution of the program. The Load toggle switch is turned up when the program steps are entered and down when the program is to be run. The In button is pressed once for each instruction or data wword to be loaded. An instruction or data word is selected with the 8 "data" switches (these are toggles) and then In is pressed. Each press of In causes the instruction or data word to be entered into the next available memory location in the RAM. Also, as In is pressed, the values set on the data switches are displayed on the two digit LEDs. One year later, in 1977, RCA released a **Microtutor II** system. It is basically the same computer but with a RCA CDP-1802 micro-processor integrated into the main board. Thus, no more "P" expansion slot, only "M" (for memory) and "E" (expansion) slots. --- **Contributor:** Paul H. Tarver (pictures & info)
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