Search Posts:

Motorola MEK6800D2 Microcomputer


Return to Threads

  Motorola MEK6800D2 Microcomputer by Bill Degnan - 01/05/2005 17:57


I have not yet tested this single board computer. I have the manual, it's very good,
should be fun. Requires a 5V DC @ 2.5 MA. I have to splice up an adapter, etc.

  MEK6800D2 by Bill Degnan - 07/16/2012 19:38
Motorola MEK6800D2
The Motorola MEK6800D2 6802 (6800) processor-based development kit from 1976. The original configuration included a 1K ROM monitor called JBUG, and a 6850 ACIA to drive a teletype or serial device. The original system shipped with 512 bytes of RAM (less than 1K). Click image for larger view.

Motorola MEK6800D2 RAM Upgrade
The previous owner of this computer upgraded the RAM to 32K. You can see by this picture that numerous jumper changes were made. If you review the detailed photos you'll see that many chips were replaced as there are chips with late 70's and even early 1980's date codes. Click image for larger view.

Motorola MEK6800D2 JBUG relocated to F000
A search of the memory map reveals that the JBUG monitor program is present at BOTH E000 and F000, but why? My guess is that the owner was trying to move the monitor to make room for another ROM to be located on E000, but did not finish the job, or changed his mind.

This was the system I took to HOPE 9 to exhibit as part of the M.A.R.C.H. club's booth. The theme was single board computers and trainers. I first got this MEK6800D2 years ago, well before 2005 when I started this web site. I used my time at HOPE as an excuse to finally to debug the entire system, run though the key chip pins with an oscilloscope, test the RAM and so on. I was surprised to find that it had so much RAM. This system has a cassette port and it would probably not be much work to install MIKIBUG and configure to run with a teletype for I/O, or a glass terminal. Given the upgrades, this MEK has more power than my SWTPC 6800.

More Pictures

MEK6800D2 Manual

  Motorola 6800 JBUG Monitor by Bill Degnan - 04/25/2013 00:01
Message from Roberto Berner:

>Comments: The monitor ROM has 1K extention, and the memory map decoder
>line selects an 8K block, so the JBUG monitor "mirrors" 8 times across
>that 8K block boundaries. You will find the same memory contents in
>$E000 , $E400 , $E800 , $EC00 , $EF00 , $F000 ... etc. I have learned
>almost everything I know with this excellent tool. Greetings from
>Buenos Aires, Argentina.



Buy a Commodore Computer Poster

Popular Topics and FAQs

  • Commodore B Series Tips and Tricks
  • Aerocomp TRS 80 M 1 Expansion Unit DDC
  • Items Wanted
  • Lobo Max 80
  • Zenith Z-19-CN
  • Prototype PET 2001 photo
  • Using Toggle Switches to Analyze Memory
  • Commodore Disk Archive Project
  • PET 2001 Prototype at Gametronics 1977
  • Jim Butterfield Photo
  • IMSAI 8080 With Processor Tech. Cutter
  • Secrecy is the keystone of all tyranny
  • Cromemco System Three
  • Northstar Horizon - Boot Problem
  • Computer History and Restoration Links
  • Commodore BX-256-80 - 8088 Co-processor
  • S-100 board testing with Z-80 ICE
  • Donner 3500 - an early portable computer
  • Digital (DEC) PDP 11/05 NC Assembly
  • Univac 1219 rescue
  • Fido BBS listing node list 6-13-1986
  • PDP 8e
  • MITS 88-2 SIO (2SIO) for BASIC
  • Visual Technology Inc Model 1050
  • Amiga 2500 Restoration
  • The Evolution Of IBM Computers
  • Replacement teletype print hammer head
  • Archiving and Copying Software 101
  • Computers Built 1940 - 1950
  • CBM B-520 (a.k.a B256-80 or B500 256)
  • RCA COSMAC Microkit
  • Commodore 64K C-116 Mods
  • MITS 8800b Turnmon 9600 baud
  • Catweasel, 8in and 5 1/4
  • Raspberry Pi as Gateway to Internet
  • Digital PDP11 late 1969 early 1970
  • PDP 11/40 72 inch cabinet model
  • PDP 11/40 Industrial 11 model
  • Digitial MicroVAX 3100 30 System
  • Digital VAX 4000-200
  • Commodore 64 / 1541 DRIVEKNOCK
  • Booting the System Using RL02 drive
  • PACS: Reflections by Kathleen Mauchly
  • Tele-Graphic Computer Systems Inc.
  • Commodore B Series SID Jukebox?
  • Installing Core into PDP 11/40
  • Setting Up OpenVMS 7.1 DNS CLERK
  • Felt-Tarrant Comptometer Model J
  • NextStation Color
  • Digital Rainbow (PC100-B2)
  • 1970 Compusad Compulogical Tutor
  • Archiving Papertapes Using DSI NC 2400
  • 1976 P.C.C. Features the MAI JOLT 6502
  • 1961 Beckman DEXTIR Computer
  • UNIVAC 1 and UNIVAC File Computer 1
  • Past Issues:

    IBM Thing

    This image was selected at random from the archive. Click image for more photos and files from this set.