Hobby Computer Kit

[MskoDestny]

I've long been fascinated by the hobby computers of the late 70s and early 80s. They were really hackable and gave the owner a better understanding of how computers work. I find it unfortunate that there seems to be very little to fill that role today (the C-One being the closest example I can think of).

To that end I'm thinking of putting together a little hobby computer kit and a book/booklet/ebook explaining how the machine works and a few "experiments" for expanding the machine. I'm a bit torn as to what direction to go in with what the base hardware should include. On the one hand, starting with an ARM or ColdFire(extension of the 68K family) SoC (system on a chip) would give enough performance to do some useful tasks (basic web browsing, MP3 playback, etc.) and they tend to come with useful built-in peripherals (timers, DRAM controllers, ethernet, etc.). On the other hand, keeping that kind of logic external to the CPU would probably be useful to the learning experience, particularly if some of it was added by the user. Also, older CPUs like the original 68K and Z80 tend to be a bit easier to hack as the busses are simpler, slower, and generally have fewer signals lines.

So this poll is here to both gauge interest in such a kit and get a feel for what kind of hardware people would like for such a kit. Feel free to comment on hardware you think should be included in the basic kit (like ethernet, audio, blinkenlights, etc.). I'd also like to know if people would be interested in assembling their own kits (surface mount components would still be soldered ahead of time) or if they want the basic stuff to be ready to go out of the box.

Here are the basic choices:
ARM SoC Based
ColdFire SoC Based
68K Family (68000 or 68020/EC020)
8-Bit CPU (Z80 or 6502)
Interested, but no idea which to choose

Note: It's very unlikely that a ColdFire version would use a V4e Coldfire so it probably wouldn't provide a very good base for an Amiga clone, though I haven't looked into the differences between the different core versions.

[vic20owner]

I did something similar with the 8085 and 8155 ram/io chips.  I learned quite a bit about cpus, address space, ports, etc from that little project.

[billt]

While not marketed to home hobbyists, there are things out there. Look up some evaluation boards for microcontrollers, they have buttons, LEDs, a serial port or parallel port, headers and sometimes LCDs and keypads.

Jameco has some stuff at Long  url edited by admin which might be suitable, some of their Basic Stamp boards should be suitable for learning stuff and tinkering and are priced for most mortals to handle.

There was also a DIY game console that came up in some discussion some time ago. http://www.xgamestation.com/about_gamestation.php Looks like fun.

I work at Atmel for my day job, and I know we have various AVR and ARM eval boards that could apply, but I don't know any prices or anything, as an evaluation board they may start stepping into expensive territory for a hobbyists's budget. There's also the FPslic, which is an AVR and FPGA combined into a single chip, but I've also seen an Atmel FPGA eval board with a socket for a discrete AVR from someone called Kanda (AVR chip not included though).

Microchip (PIC), Freescale (Coldfire, 68HC11 etc), and surely many companies have ARM or 8051 things. You might also think about a Xilinx eval board and look into some of the free microcontroller cores on opencores.org. Of course you might have to deal with higher prices or short-term licenses with some of these, especially for FPGA boards with HDL synthesizers or simulators.

[MskoDestny]

While Basic Stamp and PIC boards definately fall into the right price range, they tend not to interface with the rest of the world in a fasion that teaches a whole lot about how computers work. Instead of having a data and address bus they just have a handful of I/O lines.

The XGameStation is probably the closest thing to what I'm talking about in terms of purpose and intended audience, it's based around an SX microcontroller which has the same kind of I/O line interface that PICs do.

Most ARM processor dev boards I've looked at are pretty expensive though the AVR butterfly seems pretty cheap. However, it would seem the AVR doesn't have a standard address/data bus either.

An FPGA-based soft core would probably be the most cost-effective solution, though I personally don't find that nearly as satisfying as having a "real" CPU to play with.

[InTheSand]

Hi,

From a purely selfish point of view, I'd go for a Z80-based CPU, but that's only because it's the CPU I'm most familiar with.

For my HND (UK exam qualification) project many moons ago, I pulled apart a multi-user CP/M machine that consisted of five lots of CPU/RAM/serial I/O boards (one for each user!) and a further board containing the interface logic for its shared 10Mb hard drive.

I took one of the CPU/RAM/RS232 boards, disassembled its 4Kb boot EPROM, doubled the ROM address space from 4Kb to 8Kb, replaced it with my own OS (fairly rudimentary!), added a PIO (parallel input/output) and finally added an AY-3-8912 sound chip. I made a board containing 16 LEDs and connected that to the PIO (so I could make "chasing LED" effects), and also had the AY-3-8912 playing ripped ZX Spectrum game music.

All in all, it was a great learning experience for real low-level hardware stuff. Of course, this was all easy to solder, non-surface-mount and the hardware I added was created on standard stripboard so it was cheap too.

Anyway.... if you're targetting the Amiga audience, I guess the 680x0/Coldfire would be a better place to start...

 - Ali

[Doobrey]

@MskoDestny,
 If you're considering a simple 68k based system, have a look at the MC68306,   20Mhz 68000 core with 2 timers, 1 uart, DRAM controller,interrupt controller ,programmable external chip selects etc, the only downside for hobbyist use is the QFP package.

 Now if someone can come up with a simple 24bit gfx chipset that can do TV output and needs a minimum of glue logic to interface to the 68k, then I have a cunning idea..

[Dr_Righteous]

Guessing your kit would likely use new components, I vote for a ColdFire SoC... Simply because the ol' 68K chips are getting expensive as hell. That said, the ColdFire would be the closest to 68K instructions for assembly programs on this little kit. All aimed at more insight into our beloved Amigas.

[MskoDestny]

@InTheSand
Well this kit isn't aimed at the Amiga community in particular, though I certainly don't mind tailoring it a bit in that direction. In general, I really like the 68K family so it's likely I'd go with something of that lineage.

@Doobrey
The 683XX series chips are under consideration, but for the educational value I tend to lean towards having fewer things integrated into the CPU itself.

@Dr Righteous
68000 and 68EC020 chips are still quite cheap, cheaper than ColdFire chips in many cases. Of course you get more bang for your buck with ColdFire.

In some ways, the ColdFire 5407 is tempting. It's the only V4 ColdFire that comes in a QFP package (most of them are BGA only). Since it's a V4 ColdFire it can run CF68KLib allowing 68K code to run transparently. Some enterprising person could port AROS to a suitably expanded kit and integrate CF68KLib so that most non-hardware hitting Amiga software could run (in theory anyway). Unfortunately it's a bit on the expensive side for the purpose of this little project.

[billt]

I'm not sure what you man by "standard address/data bus".

For FPGA solutions, while it's not a "real" cpu, it is possible to get experience with a number of different architectures without having to buy tons of boards. You also get to learn about what is going on inside the CPU and how CPUs are designed. Something you don't get by tinkering with a discrete CPU chip.

I've also come across some potentially interesting books:
long link edited by admin
long link edited by admin

And if anyone gets into FPGA stuff, Verilog seems to be easier to pick up then VHDL. A good Verilog book is
long link edited by admin

I only link to Amazon for descriptions and reviews, if anyone's interested buy from where you want.

[bloodline]

Here are the basic choices:
ARM SoC Based
ColdFire SoC Based
68K Family (68000 or 68020/EC020)
8-Bit CPU (Z80 or 6502)
Interested, but no idea which to choose

I think it would make sense to use the ARM SoC. That should be the cheapest part.

I would prefer a lot of integrated toys (timers, DRAM controllers, ethernet, etc) so that one could get it up and running quickly. A Serial interface is vital for getting the thing running without having to worry about gfx and TCP/IP stacks :-) These SoC's tend to provide a normal Address/Data bus as well, so it would be easy enough to add a VGA controler and other fun stuff as well.

[TheDaddy]

Hi Everyone,

I don't know if this fits into this topic but I have had this idea for months and I would like you guys to post any advice or contact me if you want to discuss it. I have already emailed Amiga Inc. but I have had no reply yet.

This is the idea and please take into account the fact that is a draft and all the concepts are still in the early stages.

I have been thinking that producing a portable Amiga (classic games) console could be an interesting proposition. Something in between one of those C64/Atari joysticks and a PSP (less multimedia oriented though).
 
I have been sketching a few proposals for a Portable Classic Amiga Game Console and it would be nice to know of
any ideas, advice on hardware, software, possible problems, costs, obstacles and so on.

Hardware wise, emulation or native...all suggestions are welcome.

Cheers
 

 

[bloodline]

TheDaddy wrote:
Hi Everyone,

I don't know if this fits into this topic but I have had this idea for months and I would like you guys to post any advice or contact me if you want to discuss it. I have already emailed Amiga Inc. but I have had no reply yet.

This is the idea and please take into account the fact that is a draft and all the concepts are still in the early stages.

I have been thinking that producing a portable Amiga (classic games) console could be an interesting proposition. Something in between one of those C64/Atari joysticks and a PSP (less multimedia oriented though).
 
I have been sketching a few proposals for a Portable Classic Amiga Game Console and it would be nice to know of
any ideas, advice on hardware, software, possible problems, costs, obstacles and so on.

Hardware wise, emulation or native...all suggestions are welcome.

Cheers

This topic hase been disscussed at length, just search the Fourms :-)

The idea is not really feasable. But it is certainly possible to run UAE on some small XScale based platform (as many here already do including myself on an HP iPAQ 4150). But it's unlikely that you could bring any system in (no matter how you implement it) for under $200.

[JimS]

I kinda like the Z80 also, back in the day, I wire-wrapped a Z80 system from various magazine articles. It's still around here somewhere...
But the Coldfire makes more sense from an Amiga perspective.

I've been wanting to learn something about FPGAs as well, maybe using them in some sort of Amiga hack like a scan doubler or extended graphics system. I was looking at an experimenters board from XESS.com, but these guys http://www.opalkelly.com/ seem more interesting. 400,000 gates for $200, with a USB interface... fun stuff. :-) I had this idea of taking the 12-bit digital data coming from Denise and sending it over USB2 to a pc for display... or maybe putting a PCI core in there and making the Amiga's Zorro II ram space a pci memory card...

 

[hppacito]

I know this thread seems a bit dead after one month but anyways...

I'm currently planning in a 68000 replacement board based on a Coldfire 5206e or better, something QFP with 0.65mm pitch. That is difficult to solder, but not impossible.

The basic idea is:

A kind of accelerator with DRAM, Flash, IDE port.

The amiga would provide chip ram, and chipset in the right areas. Everything runing under an emulation layer.

I already got some ColFires.
And I'm thinking how I'm going to program the emulation.

But the good thing would be to make it in a kind of "do it yourself", with schematics, soft, pcb layout... (under the GPL of course !).

If you want something small, and 8 bit, I'd recommend a 68HC11, they are quite powerful and have frendly packages (PLCC) and useful periferials.

I think that an AVR is also a good idea, but you cannot expand the memory.

For quite a bit I considered using H8/300H, they have a somehow similar programming model than 68k, and are some more or less usable packages. They are 32 bit processors with 16M addressable memory. Quite cool.
I even wrote my own simulator and a ton of floating point routines for it. And also got uclinux working in the simulator, when the port was still in its infancy (2001 or 2002). kinda fun, I never got to buy the actual processors, but learned a lot about them.

Another cool line to work are the Hitachi SH-1 and SH-2. There are some QFP with acceptable pitch. those are 20 or so Mhz parts. RISC processors... I also wrote a simulator and some soft for it, like I did with the H8/300H.

If you want some ideas or some (limited) real experience, I have plenty of both to offer.

Anyway I'm pushing now this CF thing... lets see.