Motorola MEK6802-D5 single board computer

[Christoffer]

I got this for next to nothing yesturday, in working order. sortof.
It's a Motorola trainer for the 6802 processor, datecoded late '81, but the design looks more 70's-ish, so I guess it could be older.

It's a standard trainer, with HEX 7seg displays for data/address and a hex+function keypad. It features a "wrap area" for wire-wrapping your own additions, and a massive expansion connector on the back of it. It has a 6832 PIA broken out to a DIP socket for the user to use, and one for keypad/display stuff. The keypad is interrupt driven, by the way.
It has a small monitor in ROM, allowing you to punch in and run assembler code, review/set registers, set breakpoints in your program, and save/load to/from cassette.

Mine came in a very homemade aluminum case, with aclear plexiglas front (sorry for the screenglare) - complete with 220V psu.
This turned out to be less-than-ideal, since the transformer is putting out a bit more than the manual reccomends- almost 9V more, actually. The poor 7805 in a TO-3 case gets pretty hot pretty fast, but I plan to make an external 5V supply.

What makes this trainer very interesting, is that it's designed for almost limitless expansion. The card-edge connector on the back is compatible with the Motorola EXORCISER system, allowing this board to be used as a processor board for a such system, with the possibility of adding more boards to the backplane, like floppy or hard-disk controller, more RAM, and more!

The standard config is the one I have, but the board has room for a lot more. It's explained nicely in the manual, too. Under the keypad (I guess you won't need it, then, or you'd put it on a ribbon cable) is room for a MC14411 baudrate generator and the classic MC6850 ACIA serial controller, as well as RS-232 line drivers and a DSUB-25 connector, allowing it to talk with a terminal!

It has an empty ROM socket, where I believe you can put the Motorola "JBUG" rom. I don't know if that's required to run any meaningful serial comms, or it's present in the current "d5BUG" rom. Don't even know the difference, really.

Attached is a photo. I hope others has this machine too and has more knowledge/info

--Christoffer

 

[pamphonica]

10 years later, I find your post!
I just got a pair of these lovely small Motorola development boards for very little, as well!
I am quite interested in getting them to work with a terminal via ACIA, using the chip locations under the keyboard, especially as one keyboard is missing.
Did you ever find any information about using the ACIA, and more particularly, which monitor ROM would support that?
all best
Jeremy

 

[stanleyruppert]

10 years later, I find your post!
I just got a pair of these lovely small Motorola development boards for very little, as well!
I am quite interested in getting them to work with a terminal via ACIA, using the chip locations under the keyboard, especially as one keyboard is missing.
Did you ever find any information about using the ACIA, and more particularly, which monitor ROM would support that?
all best
Jeremy

Hi Jeremy,
Cool find picking up those D5 kits. Fun little boards.
The D5BUG doesn't support the added serial port capability, but one could port a number of other 6800 simple monitors as a replacement (or second userrom you could jump to from the keypad).
Previously I had ported motorola's minibug II as a test on my D5 kit. I can send some instructions for wiring up / testing the additional rs232 circuitry I had grabbed from another group.
Welcome to the vcf forums! Cheers, Stan

 

[ncherry]

I was under the impression that something from that time frame (~77/78) supported the ACIA. It may not have been JBUG, I bet MIKBUG would work also (a guess). I have 2 boards, one with ACIA (no keypad/display) and one with the keypad/display. I haven't booted them in a long time. The manuals are in the archive. I'm not able to dig them out right now.

 

[stanleyruppert]

For reference here is a comparison table of selected 6800 monitors with various attributes (ACIA/PIA/code addresses etc)
MIKBUG itself was PIA based, but did include a very minimal (MINIBUG) in the same ROM for ACIA proof of concept.
Reset vectors pointed only to MIKBUG though.
Later Motorola MINIBUG II, III, and MICROBUG were all ACIA based as were most other contemporary monitors like SWTbug etc.
For deconfliction, the 'Fantom II' monitor in the table refers to the original Wintek Corp Fantom II monitor for their line of SBCs. They later modified Fantom II monitor under contract from Heathkit for use in Heathkit ET3400 expansion unit, same name but different monitors/code.

 

[wrm]

Two or three Elenco XK-300s popped up here in Cape Town recently. I have one. Johannes le Roux ported MIKBUG to his https://www.facebook.com/groups/minimalistcomputing/permalink/1483148242775299/

 

[ncherry]

For reference here is a comparison table of selected 6800 monitors with various attributes (ACIA/PIA/code addresses etc)
MIKBUG itself was PIA based, but did include a very minimal (MINIBUG) in the same ROM for ACIA proof of concept.
Reset vectors pointed only to MIKBUG though.
Later Motorola MINIBUG II, III, and MICROBUG were all ACIA based as were most other contemporary monitors like SWTbug etc.
For deconfliction, the 'Fantom II' monitor in the table refers to the original Wintek Corp Fantom II monitor for their line of SBCs. They later modified Fantom II monitor under contract from Heathkit for use in Heathkit ET3400 expansion unit, same name but different monitors/code.

View attachment 1315833

The Original MIKBUG (1.0) was PIA based, a later version (1.1?) was PIA/ACIA based. I think it was in one of Motorola App Notes I found this.

Wrm, I think you are correct that minibug was ACIA based

 

[MiaM]

I haven't got much to add to this thread, except that I also own one of those.

I added an ACIA (happaned to have a Hitachi 6350, compatible with the Motorola 6850) but I didn't have the intended chips for baud rate generation so I used a divider (probably 74HCT4040, can't remember) and I might had used a gate to be able to divide by something else than an even power-of-two. It's well over a decade ago so the details are fuzzy.

Anyways I had some sort of plan on modifying the monitor to accept input both from the keypad and the ACIA, and also somehow output both to the LED displays and the ACIA, but I didn't get that far.
If you want to tinker with it, I'd recommend looking into using the cassette interface to transfer data to/from it, so you don't need to use the keypad or use a ROM emulator or whatnot.

I also had some sort of plan on modifying it to be compatible with the SWTPC 6800, and/or modify the monitor and whatnot for the SWTPC 6800 to work with this board. Again never got around to actually do that.