Looking to build my first SBC, advice welcome!

[free_electron]

I meant: what would people WANT on a "modern" x51 SBC?

an F120 cpu !

[westfw]

OS9 was supposed to have been a pretty sweet system.  I don't know if you can still use it.


Also, didn't MIT have a 6811-based robot board (handiboard?)

[westfw]

The Radio Shack Color Computer ("CoCo") was the most well-known 6809-based personal computer.  It ran OS9, I think.  (OS9 was vaguely unix-like, along the lines of MSDOS 2.x)   Unfortunately, it was likely to have been based on a bunch of support chips that are hard to find any more (but perhaps good candidates for implementing in an FPGA/CPLD.)

The MIT Robotics board was "Handy Board", and it looks like there is still some support community.  I'm not quite clear on the relationship between 6809 and 6811; The 6811 is more microcontroller-like (and one of the big claims to fame was some eeprom memory that could be used for short programs), and is "similar" in architecture.  But "similar" could mean as far off as 6809 is from 6800, or 8086 from 8085...

[Crazy Ape]

You could always design a board that could take either a 6502 or a 6800, you'd just need to map in a different boot-rom based on which CPU you have plugged into the board.

Other than a slight clocking difference you'd need to cater for, the two CPUS are almost interchangeable at the hardware level. The Apple 1 board for example,  had this interchangeability designed into it.

Some more info:
"The Apple-1 motherboard was designed in such a way as to make it possible for the hobbyist to remove the 6502 processor and use a Motorola 6800 as the CPU instead. This was not a trivial operation, as the 6502 and the 6800 were not pin-compatible (the earlier 6501 was pin-compatible, but was withdrawn after Motorola sued MOS Technology). However, some other hardware would need to be added, and the software needed to operate it would be completely different."
http://apple2history.org/history/ah02/

Video of Apple 1 board running with a 6800.


The pin-outs are very similar.
http://www.cpu-world.com/info/Pinouts/6800.html
http://images.wikia.com/microchip/images/e/e5/MOS-6502-pinout.jpg

[BulletMagnet83]

That's a cool-looking system! I'm hoping to build rather than buy, but once I get home from work I'm gonna have a proper read through the docs and see if there's anything in the design I can steal. I'm quite taken by the red/green address and data displays, that definitely needs robbing for whatever I build if only for the aesthetic appeal.

Given we've had a slow day today I've spent most of it reading more about Grant's projects, and doing some datasheet diving... and now I'm leaning towards the 6502 version of the simple SBC, possibly built with WDC's brand-new compatible parts so I don't have to take any chances on eBay shitpiece socket-pulls that may or may not work.

Mouser seem to have everything I need: The CPU, ACIA (65C51, which the datasheet claims is a replacement for the 6850), and the 65C22N VIA. I thought I might as well get a few of those when I get around to a parts order, as I pretty much have a complete system then, with all the I/O I could possibly want.

Has anyone reading this thread worked with WDC's 65xx toolchain before? I know it's not going to be a piece of piss like Arduino but how's the learning curve on it? If all I want to accomplish (to start with anyway) is to shove some bytes around to prove the machine works is there anything else I should be using? If the machine WORKS and I decide to take things further, $40 for a proper licence doesn't seem like a lot.

[Crazy Ape]

Lots of home made 6502 systems to gain knowledge from.

http://www.6502.org/homebuilt/

[senso]

No love for the intel 80186, my first experience with what I call crippled micro-controllers was in the university, programming this bad boy in assembly, REAL funny to put half the address bus and the data bus into two breadboards and then implement address decoders with discrete logic, shall I say, I failed the subject due to a busted 4 bit buffer that was half dead, half because at each power up the outputs would either choose to be high or low, regardless of the inputs, and the professor never discovered what was going on, he said, maybe its a wiring fault, rip that crap and redo it(again, I have made that mess of wires 3 times), in the end, I couldn't program or follow the class, so bye bye till next year..

That and the segmented or what the hell was the memory distribuition 

[westfw]

if you don't want to debug hardware, and don't want to put up with "weird" architectures, you might as well stick with programming in python on a raspberry pi.  (that way, all you have to learn is unix system administration skills!)

[legacy]

anyone knows an EAGLE's project for such a SBC ?

[westfw]

I have several 8051 "paper" designs (not built yet, so I don't know whether they work.)

[legacy]

I realized an 8051 board, and a 68000 board, also a 68hc11 is up running out of the proof of concept, any way i was used to use Orcad software which i was licensed at work, at home i just have a licensed copy of Eagle Cad, may be also a copy of PCB Express, but ... never done nothing with them, so i am looking for a short start up.

[zx80nut]

Hi.
I stumbled on this forum by accident looking for something, and I saw my pages mentioned.
...and yes, they really do work

Regarding the 6809...
The E output is directly derived from the incoming clock / 4 and is constant rate, so this is ideal for running the 6850 baud rate clocks (as well as the E signal for which it is intended).
7.3728MHz / 4 = 1.8432 MHz to the ACIA. Then using a div 16 clock setting in the ACIA, so 1.8432 MHz / 16 = 115200, giving the required exact baud rate.

As has been mentioned, the 6850's are being overclocked but I have had no issues with any of my chips, however, use a 68B50 if possible (I actually updated my web pages to mention this earlier today )

Several others have built the 6809, 6502, Z80 and CP/M designs with no issues (I'll be adding a photo gallery of other people's builds to the pages shortly), but please feel free to contact me if needed - I'm more than happy to help out.

Regards.

Grant

My simple SBCs...
http://searle.hostei.com/grant/6809/Simple6809.html
http://searle.hostei.com/grant/z80/SimpleZ80.html
http://searle.hostei.com/grant/6502/Simple6502.html
http://searle.hostei.com/grant/cpm/index.html

My main page...
http://searle.hostei.com/grant/

[zx80nut]

Hi.
Bit more help regarding this thread...

Above someone mentioned using a 6551 instead of a 6850. They are not identical so can't be interchanged as-is.

However, a 6551 can be used instead of the 6850 with minor code changes (the status bits to be checked/control registers to use x16 external clock) and I can design the replacement code needed if required - please feel free to ask. I'll see if I have a spare 6551 and I'll try it.

Many designs are on the net, but my goal was to produce a design that really can be used by beginners and experienced people alike. They are intended to be the simplest practical expandable and useable design that I could do so that the core design is not hidden inside a more complex schematic. They can be built and work "out of the box" exactly as-is, all have been tested by rebuilding by myself and others, and then you can expand as needed without the clutter of already-present peripheral chips that may not be needed in your design.

SBC schematics often look complex due to expansion devices already present on the design, I hope to show how easy a computer system really is.


Regards.

Grant
http://searle.hostei.com/grant/

[legacy]

it would be pretty if we design a pcb in order to realize these tiny boards, what do you think about ?

[westfw]

Someone should do a PCB featuring the "common" components (RAM, EPROM, UART?  Is there a 32pin or smaller parallel IO chip?)  Maybe using a cheap modern connector (PCIe, like the Freescale "Tower" boards?  Only smaller?)

[legacy]

i have found this 6809 project, it looks pretty with schematic and files included

[legacy]

here, in my free time, i am still toying around building a 68hc11-F ("F" means no multiplexer, and much more internal ram, ~1k) board.

any news, guys ?