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68K-MBC assembly instructions, setup and user guide?

R

rwcooper

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Jan 17, 2023
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Hi, I just received a 68K-MBC full kit. I was expecting there to be instructions on assembly, setup and usage. I'm finding it very difficult to find any useful documentation on the 68K-MBC. If anyone can point me to online documentation regarding this or provide me with information I'd really appreciate it.

Thanks, Randy.
 
Have you looked at,
hackaday.io

68k-MBC: a 3 ICs 68008 homebrew computer

The 68k-MBC is an easy to build 68008 CPU SBC (Single Board Computer), using only easy to find TH parts. It follows the same "concept" of the previous Z80-MBC2 (https://hackaday.io/project/159973) and V20-MBC (https://hackaday.io/project/170924) boards, using a PIC18F47Q10 MCU as EEPROM and...
hackaday.io hackaday.io
 
Thank you for the link. It looks promising. I did find a link to this project on hackaday, but it was not as good as this one...Randy.
 
Regarding the 3-Chips 68008-based 68K-MBC - Is there any way to connect this to a bus ?? Something like the RC2014 or similar ?? Address Lines, Data Lines, Control Signals ?? To allow this SBC to connect and communicate with a second Card or Kit or ... ?? If not this one, Does anyone know of a different 68008 SBC Kit that > IS < Compatible with an expansion bus ?? Does not need to be compatible with other Z80-Based RC2014 Cards. Just use the Backplane ?? Example of a second card might be a DUART board with a 68681 DUART ?? Timing and handshake might only match between MC68k -Based Cards ??
 
Pt68k5 - Thanks Very Much for your posts. I did have the Mega-Micro page Bookmarked, and also the 68K-MBC "3-chips" board. And I have looked for and read all the Bill Shen Plasmo or Plasmode SBC projects I could find. And I have also read up on the whole ECB Bus which is sadly now dead. The S100 Google Group and Facebook S100 remain active thus my choice of S100 68008 SBC - project on a goal of a single S100 prototype board.

What I am wanting does not yet actually exist so far as I have found. I want to try to squeeze an MC68008 CPU with a single 512k x 8 Static RAM, and Something Similar to an EPROM that is roughly the same size internally. Both 512k x 8 - to hold BIOS, Monitor, and maybe CPM-68K in EPROM, etc. UART either a single or pair of 6850 UARTs or a single MC68681 Chip. A Power Socket for off-board 9V DC Wall-Wart and a 7805 or Switching Equivalent for +5V DC power. Goal = Stuff ALL of this in as small as possible space on a Single S100 prototype board. If I could get there, as an SBC, then look at the S100-Bus interface afterwards.

This idea is inspired by the Very-Recent Z180 SBC for S100 created by John Monahan - His S100Computers.Com website and he frequently posts on the S100 Google Group online. My idea is to "do the same thing" but this time with the 8-bit 68008 CPU. Smaller chip better for squeezing as much as possible onto the one S100 card which is about only 5-inches High by about 10-inches Wide. John already has the 68000 CPU / 68010 S100 Master/Slave card. The 16-bit version. Huge Chip. And both Odd and Even ROMs and RAMs. By using the 8-bit 68008 uses only a single RAM chip and a Single EPROM chip. John has the 68000 S100 card But it Does Not Have Either a UART or DUART. I hope by using the 8-bit CPU chip and the one-each RAM and EPROM, I hope that there will be enough room then to stuff in a Single UART or DUART and use the MAX232 chip or chips. Stick with 5-volts only where-ever possible. No +12 and -12 V Regulators for the MC1488 + MC1489 pair. "Tradition" says use the + & - 12V and the two MC 1488/89 chips. But keeping it all as small as possible says use the MAX232 or equivalent. The Z80 S100 SBC already exists. And the JAIR 8080 CPU SBC also exists. But I am a fan of the m68k. When I have looked around, the ROSCO 68000 motherboard comes closest. But the cards for the ROSCO bus are few. I started a long long time ago with the Altair8800b but using the SAGE 2 and SAGE 4 in College made me want my own 68000 Home-PC - not implying any relationship to the IBM PC. I owned a Xerox 820-2 with the 8088 Co-Processor Card. CPM-80 2.2 and also MS-DOS 2.0 on an 8-INCH Boot Floppy. I've spent 40 years on IBM PC descendants as an On-Site Xerox Computer Repair team and also the Xerox Computer Repair Depot Shop in Redmond, Washington IIRC. And spent decades of IBM PC Compatibles. 8080, 8085, and Z80, Z180, and Z280 are not attractive to me as I have already "Been There Done That". But that 40-years "Lust" for my own 68K Home Computer, Inspired by wanting a SAGE 2 or 4 Computer never died. I wanted my own Sage. Still Do. But in the S100 Bus.

I hope that all of the above gives you a very clear description of what I want and Do Not Yet Have - My Own SAGE-Equivalent Home Computer. And NO The 68K Apple Mac computers and the Amiga 68K Computers and the Atari ST 68k - All of those feel like "Gamer Machines" and NO I am NOT a Gamer. I only play Klondike-Style Solitaire. Like on Windows and Linux.
 
Harry, I would look at using the 52 pin version of the 68008 as it supports 4 meg of address space and is in a plcc package which uses less space
The kiwi is based on the 68008 https://www.ist-schlau.de/hardware.html
And also there is the Katy which is also using the 48 pin version https://www.bigmessowires.com/68-katy/
Mega-micro offers bore boards for the 68000 and the 6850 or the 68681 using a 16 bit eprom to hold bios and Cp/m all in one chip which would get you started and the are small, he has two different versions on 68000 cpu boards, one is the plcc version
 
Harry,
S100 is enormous amount of board space! How do you feel about CPLD in board designs? CPLD saves lots of board space so what you want can be done in 2"x4" pc board if CPLD is involved. For 68000, the idea is eliminating 2 EPROM and use x16 DRAM and bootstrap from CF disk. So the core design is 3 chips (68000, DRAM, CPLD) + CF disk. A DUART can be added to the core design. It can be something like T68KRC (3"x4"), but smaller because the serial bootstrap EEPROM is replaced with existing CF disk.
Bill
PS, if you accept serial bootstrapping, then CPLD and DRAM can fit inside the footprint of DIP64 68000, so the core design is not bigger than DIP64 68000.
PPS, another small design is based on P90CE201 which is derived from 68008. Kuno fits in Arduino Mega enclosure.
 
Last edited:
Plasmo said:
Harry,
S100 is enormous amount of board space! How do you feel about CPLD in board designs? CPLD saves lots of board space so what you want can be done in 2"x4" pc board if CPLD is involved. For 68000, the idea is eliminating 2 EPROM and use x16 DRAM and bootstrap from CF disk. So the core design is 3 chips (68000, DRAM, CPLD) + CF disk. A DUART can be added to the core design. It can be something like T68KRC (3"x4"), but smaller because the serial bootstrap EEPROM is replaced with existing CF disk.
Bill
PS, if you accept serial bootstrapping, then CPLD and DRAM can fit inside the footprint of DIP64 68000, so the core design is not bigger than DIP64 68000.
PPS, another small design is based on P90CE201 which is derived from 68008. Kuno fits in Arduino Mega enclosure.
Click to expand...
Bill - Thanks for the suggestions. Excellent. However I presently have a LOT to learn about this and buy more "tools". I don't yet have any sort of "chip burner" whether EPROMs or CPLD Chips. I also do not yet own an oven for joining tiny surface-mount chips. I do not yet own an O'scope nor Logic Analyzer. I do own a very-old but dependable Fluke DVM and am fluent in it's use. ;-) So I'm about as newbie as ever was. I lack all of the above for a 40+ years career in "swapping FRU's" (IBM Parlance). Pull misbehaving part, insert new one, power it up again. So No Experience and few tools. I've been kicking around the idea of adding one more SBC card to the S-100 / S100 community but this time based on the 68k. So I am specifically targeting the S100 bus and try to fit all these into one S100 prototype board - 68008 CPU, One Single EPROM or EEPROM or equivalent (like Flash), One Single Static RAM Chip, A UART or DUART chip with 2 choices: Mode 1 = RS232 I/O, - or - Mode 2 = TTL-Level Serial IO to USB IO. A number of these chips are available in DIP package suitable for wire-wrapping, for example, or point-to=Point soldering. Other chips with PLCC sockets would also be used. For Context, consider that the S100 users groups have an 8080 CPU All-In-One JAIR Board from Josh in Canada, And then a Z80 SBC S100 Card by John, and most recently a Z180 SBC that John Monahan also created. You might think there are plenty of S100 SBC's available and you'd be right but my focus is on all things 68000-Family unlike most of the S100 groups which are the Intel and Zilog crowd. Anyhow, I think that this will be do-able but I have a LOT to learn before I could ever "Breathe Life" into my S100 68008 CPU SBC Card. And sadly my progress is very slow as I am disabled / Retired. PS - Bill - Thanks for all of your inspiring projects in 68k SBC's. Very encouraging. So thanks again. :-) HSS
 
Harry.Speer said:
For Context, consider that the S100 users groups have an 8080 CPU All-In-One JAIR Board from Josh in Canada, And then a Z80 SBC S100 Card by John, and most recently a Z180 SBC that John Monahan also created. You might think there are plenty of S100 SBC's available and you'd be right but my focus is on all things 68000-Family unlike most of the S100 groups which are the Intel and Zilog crowd. Anyhow, I think that this will be do-able but I have a LOT to learn before I could ever "Breathe Life" into my S100 68008 CPU SBC Card. And sadly my progress is very slow as I am disabled / Retired. PS - Bill - Thanks for all of your inspiring projects in 68k SBC's. Very encouraging. So thanks again. :) HSS
Click to expand...
Presumably you're already familiar with:

S100 Computers - 68000 CPU Board

S100 Computers 68K CPU board
s100computers.com

S100 Computers - 68030 CPU Board

S100 Computers 68030 CPU Board
s100computers.com

Similar there's also (non-Plasmo):

boards:ecb:kiss-68030:start [RetroBrew Computers Wiki]

www.retrobrewcomputers.org www.retrobrewcomputers.org

boards:ecb:mini-68k:start [RetroBrew Computers Wiki]

www.retrobrewcomputers.org www.retrobrewcomputers.org

Just some other possible leverage points :->.
 
I guess what I would like to see is the ECB Mini 68k which is a 68008 CPU chip and "port it" to the S-100 / S100 bus. But whereas the ECB Mini 68k requires a second ECB IO card in the same bus, I would like to try to squeeze at least one UART (16550 ?) or DUART (68681 ?) into this prototype 68008 SBC for the S100 bus. If I ever get this far, I would certainly start with that ECB card on a prototype board for S100. There might not be enough space (5-inches by 10-inches ?), for all of it on a single prototype board so I may have to piggy-back a second prototype card - a "sister" board. And for the prototype, I'd start with the same kind of 9V supply input that John Monahan used for his Z180 SBC card recently. He gave credit to Steve Cousins. Get it to work as an SBC with no S100 interface. Get it running that way first then add the S100 interface later. This is what John did. Now the question is this: is this something I could ever actually do ?? Probably not, but I can at least "daydream" about it. :-) The path I choose has almost nothing to do with the Intel / Zilog processors that are usually on the S100 Bus. Been there, done that. CPM-80 2.2 and MS-DOS for example. Later FreeDOS. I'm thinking CP/M-68k to be the goal, after getting it all working, after the monitor of course. Damian Wilde, of Australia (I think), has done a great job of "Blazing a Path" or "Paving the Road" before me. He has already been very helpful to me and I am deeply grateful. :-) And I've read Bill Shen's (plasmo or plasmode) 68000-Family designs with Great Interest. Excellent SBC's. But I prefer having a bus. Doing that is not "taboo" for the S-100 crowd.
 
January 10th, 2025 - Harry here again. Just an update on my goal of an S-100 SBC with 68008 CPU, 1x EPROM or Flash, 1x Static RAM, 1x 68681 DUART or equivalent, using either +12V and -12V with mc1488 and mc1489 to create RS-232 -- or -- instead use one of the many +5V-only MAX232 types of chips. Serial Port 1 used for Terminal "Console:" and then Serial Port 2 for Downloads & Uploads with a supportive host computer. Note: NOT Using any USB Ports with this, just good old RS-2332. The 68008 S-100 SBC may, or may not, have any pseudo "disk drives" such as an SD card or a CF card. The use of a Host computer for virtual Disk I/O is well supported by the S100 Google Group and a FDC+ Floppy Controller Card which has it's own Serial Port.

While the S-100 Boards are available for a 68000 CPU Card and also a 68030 CPU, Thanks to John Monahan, neither of them has it's own serial port. An S-100 novice would need to build at least 2 cards - The 68K S100 CPU Card - AND - then also a Second S100 card for the Serial "Console:" IO. For a novice to build 2 cards as an untested pair of boards when one is brand new to the S-100 / S100 RetroBrew World or the Vintage Computer Federation, that's a HUGE challenge.

Thus the SBC S-100 cards using the 8080 JAIR made by Josh Bensadon of Canada, and also John Monahan's Z80 SBC and Z180 SBC. So thanks to John and Josh, we have Intel & Zilog SBC's. Note the absence of a Motorola 68xxx SBC.

Looking ahead, I want to build a second computer with a 68030 CPU and the CPU Card on a Bus that has Both 32-Bits Address and also 32-bits of Data. I have looked and I found found only the Mega-Micro in the UK which offers the full 32-bits Bus for Both Address and Data. See his Mega-Micro here: https://www.mega-micros.co.uk/68030_sbc-2.htm - Then a weird idea came to me: Use the S-100 Prototype cards to build the boards * BUT * then have the Cards plug into the ECB Bus Backplane. Does ECB handle Both 32-Bits Address and also 32-bits of Data ???

Can anyone tell me whether the ECB Bus can handle both 32-bits of Addresses AND the 32-bits of Data ?? With the ECB Bus connectors using 3-Rows - ABC - and Each Row has 32-pins - Total of 96 pins on the ECB Bus, There * SHOULD * be enough room for it.

There is the ECB "KISS" 68030 CPU Card BUT once again it relies on a Second ECB Bus Card for the Serial "Console:" IO like a Serial RS-232 Terminal. Can anyone here tell me just Exactly what is the ECB Bus Specifications ??? If there ever WAS an ECB Bus Definition or Specification ?? I just need to know whether using an ECB Bus Backplane will allow bi-directional "dual" 32-bits ?? Address and Data ??

I think it likely pretty obvious that there is "no future" for a 32-bits CPU and Such on the S-100 Bus. Even using the IEEE-696 standard we only get 16-bits of Data. A severe hobbling of a 32-bit CPU forced to always treat the Bus as a 16-bits only Bus. Like tying one's legs together and then trying to Walk or to Run. Thus I see no future 68030 builds using the S-100 Bus. Nor any other 32-bit CPU's. So what about ECB ?? Anyone ??
 
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