Project Kiwi - an 68k Homebrew Computer

[nicholas]

These pages describe Kiwi, a Motorola MC68008-based computer system which was       developed and built as a hobby. The intention was rather to start another FPGA based project,       but to design a classic computer with dedicated controllers and a count of 74 TTL chips. As for design,       the goal was to create a computer system which could have existed in the 80ies. As for a typical homecomputer,       the system needs some kind of input, output and mass storage. With this in mind, I started to       draw schematics and created the printed circuit board (PCB) layout. In respect to the design goal,       old and obsolete chips were not excluded, whereby chip brookers helped to get all needed parts.       The PCB has been manufactured from my layout data by PCB-Pool.       After soldering, I began porting Lee Davison's Enhanced Basic 68k to Kiwi.       A Basic interpreter, which is free for personal or educational use.       First, with interaction via a serial connection. Over the time, I wrote routines for       the video controller and the keyboard interface. When the system ran stand-alone, I proceeded adding       more functions. I ported an freely (GPL) available FAT filesystem library       as well as a freely (BSD License)       available TCP/IP stack.

      For the future, my plans are to program some simple games.

      Specifications:
CPU MC68008, clocked with 10MHz
      RAM4MB DRAM, 512kB dedicated VRAM       VideoYamaha V9990 Video Display Processor
Audio dual SID stereo (MOS6581 or MOS8580)
Mass storage IDE/ATA and floppy disk interface (WD177x)
Time/Date Realtime clock Epson RTC72421
      Network 10base-T Ethernet (CS8900a)
Interfaces PS/2 compatible Keyboard and Mouse ports
Two Atari style Joystick ports
      RS232 and parallel ports
ROM32KB EPROM with IDE/ATA Boot Code
Operating system Enhanced Basic 68k

http://www.ist-schlau.de/
https://www.youtube.com/user/Bogog75?feature=watch

Just needs a nice lightweight operating system like AROS methinks!

[kamelito]

Lovely, but why a 68008?  Kamelito

[wawrzon]

aros is still everything else than lightweight im afraid. it would hardly be a pleasure to run it on 68000 class cpu. more work is needed and more involved experienced coders. sorry to say.

[bloodline]

aros is still everything else than lightweight im afraid. it would hardly be a pleasure to run it on 68000 class cpu. more work is needed and more involved experienced coders. sorry to say.

AROS is still more lightweight than Linux

[commodorejohn]

Man, for dual SID I'd almost put up with the crippling performance issues that a 68008 would bring.

[mfilos]

Simply outstanding!!!
I see lots of dedication and passion in this project. Amazing work!
Thanks for sharing.

[danbeaver]

Is this the one in Radio and Electronics Magazine in the late '80s?

[Dr.Bongo]

(Audio dual SID stereo (MOS6581 or MOS8580))
I can see many a poor defenceless 64 being raped of their voice.

The idea of the machine is intriguing though....

[mfilos]

You can easily find LOT of SID chips without removing from working C64's.
Other devices uses SID chips like MidiBox SID, SammichSID etc.

[Dr.Bongo]

You can easily find LOT of SID chips without removing from working C64's.
Other devices uses SID chips like MidiBox SID, SammichSID etc.

Easily? No. For a cost yes, but there isn't a 'LOT' of them spare out there.
 I'm well aware of the Midibox, SID station, hardSID etc.

[TheBilgeRat]

from Wiki:

To support lower-cost systems and control applications with smaller memory sizes, Motorola introduced the 8-bit compatible MC68008, also in 1982. This was a 68000 with an 8-bit data bus and a smaller (20 bit) address bus. After 1982, Motorola devoted more attention to the 68020 and 88000 projects.

So...an MC68008 is actually an even crappier version of the 68000.  Sign me up :rolleyes:

[commodorejohn]

Yeah, that's what baffles me here - the 68000 had enough performance issues on a 16-bit bus!

[psxphill]

Lovely, but why a 68008? Kamelito

1. less tracks on the board.
2. you can use one 8 bit rom to boot from rather than two or a 16 bit rom.
3. simpler ram interface logic.
 
I don't have a problem with 68008, but a couple of VIC IIs would have been more interesting.

[matthey]

from Wiki:

To support lower-cost systems and control applications with smaller memory sizes, Motorola introduced the 8-bit compatible MC68008, also in 1982. This was a 68000 with an 8-bit data bus and a smaller (20 bit) address bus. After 1982, Motorola devoted more attention to the 68020 and 88000 projects.

So...an MC68008 is actually an even crappier version of the 68000.  Sign me up :rolleyes:

The 68008 is for small, cheap, easy to program processor for embedded, hobby and educational projects. It's still a full 68000 inside but has less external wires to mess with or pay for. Think of a processor for something like a keyboard. It is still more powerful and easier to program that a 6502 for example. Availability is a problem though. There was a college in Ireland that was using the 68008 with breadboards for college courses and made an fpga version when the 68008 productions stopped. The 68008 is rather weak for a main CPU considering the other add-ons. A Fido or ColdFire wouldn't be much more expensive and makes more sense in a lot of ways.

[Steady]

@nicholas

Really nice looking project. I wish I had your skills.

Just one question. You use a 68008 and say you have 4MB RAM. Since the 68008 only has 20 address bits, are you using bank switching for this?