SD Card

[Editor]

I'm continuously mixing and matching cards - which makes a case a bit of a problem.

This is actually great to hear! As "mixing and matching cards" is exactly what my original primary intent for MECB was (and still is).

I was considering something a bit simpler just to make moving everything a bit easier and perhaps just having a base onto which I can mount the main bits and pieces but still have access to the bus for unplugging/plugging. I'm just not well set up for building such things (and I don't have a 3D printer) - perhaps a simple perspex sheet would work ... or I could go old-school and do something out of plywood.

Yes, I'll be interested to se what you come up with. For my experimentation purposes, I'm perfectly happy with just the suppled Nylon PCB stand-offs as a good base. I imagine if you wanted to make a base plate from a piece of thin hardboard or perspex, then the other end of the stand-offs would probably screw to it quite nicely, with the extra supplied screws.

The top is probably more of the challenge. How to protect your system, but still make everything easily accessible? (for mixing and matching cards!).

[epaell]

At the moment I'm just looking at having just a simple board onto which everything attaches - mainly just to stop boards sliding around and potentially shorting. Anyway, I went to Bunnings (our local hardware store) and got a bit of plywood. I now have the computer side of things fastened to it. I just need to work out how to do the same for the terminal side (which I just realised doesn't have mount holes on anything) and the USB power board.

In other news ... I just compiled my first C program under FLEX - crikey, that took longer than I expected as I had to remind myself how to run FLEX, how to use the editor ... and how to run the compiler. Anyway, managed to get the sieve program running (from 80's fame for comparing compiler/interpreters on various machines at the time):



LOL, and made use of the RTC to measure a blisteringly fast run time of 8 seconds for 10 iterations

[epaell]

Of course, I could've edited the code on my Mac, cross-compiled it there and then transferred to the "system" for running ... but where would be the fun in that?

[bugeyedcreepy]

Of course, I could've edited the code on my Mac, cross-compiled it there and then transferred to the "system" for running ... but where would be the fun in that?

lol! Nice!

[Editor]

In other news ... I just compiled my first C program under FLEX - crikey, that took longer than I expected as I had to remind myself how to run FLEX, how to use the editor ... and how to run the compiler. Anyway, managed to get the sieve program running (from 80's fame for comparing compiler/interpreters on various machines at the time):

Wow! That sounds like very nostalgic fun! It's been so long since I last used FLEX that I really don't have any recollections of how things work.
Although, they do say that once you've experienced something, the memory is still there, just buried in your subconcious.
Hopefully, I get a chance (sometime soon), to try my own FLEX rediscovery journey, and see if some memories come rushing back!

I've spent the last week buried in my CreatiVision Controller project, which I believe I now have operational. I'm just waiting for my second prototype PCB to arrive for some final testing. It's been a real fun and challenging project. Meanwhile, I've started on my next video.

[epaell]

The FLEX nostalgia was indeed fun ... although I never programmed with C under FLEX back in the day and one oddity was that the Editor uses "#" to exit out of insert mode ... so I was struggling to work out how to do something basic like enter "#include <stdio.h>"! I had to do something silly like use a different character in place of "#" and then search and replace that character with the "#" I wanted in the first place. Ah, the good old days - perhaps I should read the manual a bit more carefully

I've been trying to look into what's involved in booting up NitrOS9 but I'm struggling to find instructions on how to adapt it for systems other than the ones that they have available or even how to get one of those up and running. Everything seems to assume you already have computer (typically a CoCo) already set up and just have to insert disk and type "DOS" - sigh! I think I modified the Corsham Technologies version (which is using the same disk protocol as I used for the FLEX system) and it has generated a disk image but it's unclear to me how everything connects together to start the boot process (it's not the same as for FLEX and OS9 clearly needs access to interrupts for the multitasking so must need access to the vectors). The other complication is that most 6809 systems use a kind of primitive memory management (they have a small bit of RAM (DAT) in the top part of the memory map which allows switching of different memory banks) - the Corsham system has this as well but the MECB version doesn't and it is unclear to me if that too will cause problems (I don't think it is being used but they seem to be doing things with it in the modules for it - but I don't fully understand what they are doing or whether they are just initialising it for a basic memory map). Basically I need a mix'n'match between a simple CoCo 1 version (no DAT memory) but with the I/O from the Corsham version (6850, 6821, RTC). Ah well, I'll keep searching. Unfortunately work is keeping me away from this more fun aspect of exploring.

I look forward to seeing more of your CreatVision adventures

[Editor]

I've been trying to look into what's involved in booting up NitrOS9 but I'm struggling to find instructions on how to adapt it for systems other than the ones that they have available or even how to get one of those up and running.

I suggest watching the recent video series by Boisy Pitre. He has been busy porting NitrOS9 across to the Foenix 256K.

I guess the first target for a MECB 6809 system would seem to be NitrOS9 Level 1, given that this is for a basic 64K memory map (Like CoCo 1 - so no extended paged memory).

Here's the play list. Very interesting in any case.
https://www.youtube.com/playlist?list=P ... MYqnfq7oDZ

I also recently bought Boisy's book "CoCo The Colorful History of Tandy's Underdog Computer".
I've never owned a CoCo, but it seemed like a very interesting 6809 related book to have on the shelf.

[epaell]

Yes, I agree, level 1 is the way to go and the basic CoCo 1 memory map is roughly what I'm aiming at (though I also need to get the hardware side of things right too ... so with a dash of the corsham system).

Thanks for the pointers to the Boisy's videos (I noticed his name all over the NitOS9 source code - so it's likely to be straight from the horse's mouth) - looks like he has a description of the DAT so I can try to see what bits I need to surgically extract from the Corsham version (or surgically insert into the CoCo version). And also a description of the boot process ... so will definitely have to give that a look when I get a chance.

My first "personal" computer was a CoCo so I have very fond memories of it. I pretty much grew up in a Motorola household and was probably the black sheep of the family once I entered University as I had to use an IBM PC for my Engineering degree (it didn't stop me from making a 68000 co-processor for it as my final year project though ). I also had an Amiga 500 for the "fun" stuff (I never owned a games console). Apart from a bit of dabbling with our high schools Apple II's (and clones) I never went through the 6502 or 8080/Z80 phase (so have no experience of C64s, VIC-20s, Atari's, System 80's, etc ... but it's been interesting exploring what I didn't miss via MECB and MAME - LOL!). I basically went from a 6800 home-brew (with cassette interface and 20 KB memory) to 6809 home-brew (with a whopping 56K RAM and disk drive, where my brother set up FLEX and OS-9) to 6809 CoCo (cassette and disk) and then Amiga 500 68K (and a 8088 PC - ew!). Sadly, my memory of the details are all very vague now after 40 years - particularly the 6809 FLEX/OS-9 system ... I don't even remember how I started up the OS-9 system (I just recall it seemed both powerful and overwhelming at the same time).

[lenzjo]

Here's the play list. Very interesting in any case.
https://www.youtube.com/playlist?list=P ... MYqnfq7oDZ

I also recently bought Boisy's book "CoCo The Colorful History of Tandy's Underdog Computer".
I've never owned a CoCo, but it seemed like a very interesting 6809 related book to have on the shelf.

Thx Greg, that's a nice series - just watched the first vid. That F256K system is interesting if not a bit expensive, but I did notice the cpu addon a 6809/6803 with the pin-out of a 65c02.

[Editor]

Thx Greg, that's a nice series - just watched the first vid. That F256K system is interesting if not a bit expensive, but I did notice the cpu addon a 6809/6803 with the pin-out of a 65c02.

Yes, I've been following the F256K evolution for some time. Mainly because of the FNX6809 CPU option. Quite expensive though, and more of an interesting system for someone who just wants a pre-built retro system to develop software on (as opposed to overall 8-bit hardware & software experimentation).

The FNX6809 CPU is indeed a cycle accurate implementation of the 6809, with a 65C02 pin-out. Implemented as a FPGA core on a 40-pin DIL carrier board. The only thing is that it's really only useful for the F256K, as it's 3.3V powered! So you can't just drop it into an existing 65C02 system (5V powered), DIL socket!

A pity, as if it were 5V powered it could (in theory), open up experimentation like dropping it into a C64. Of course, you'd need to re-write all the code to drive the C64 hardware with a 6809, but I could see this could be a fun project for the C64 hardware (or other existing 6502 systems).