[v2.0] MECB TMS9918 / TMS992x VDP Video Card

[bugeyedcreepy]

Do you guys watch The 6502 Show on YT? Despite the title, recently he has started off down the 6802 path as well. He has added a CF "drive" to it and yesterday added FLEX to it. Besides that he provide a number of links to the relevant 6802/09 docs. All good stuff.

Oh, More handy stuff! I will have to check it out, sounds like I need it... Thanks again for that!

Thank you @bugeyedcreepy for the offer, but I've already got the hardware waiting to be put together. I'm just lacking the software I'm coming at it from the 6502 side as I can work with that a lot faster, once I have the drivers working I can hopefully translate it to 6809 speak. I would really like to get os9 working but that's far off at the moment.

I would still like to get SD cards working as then I can transfer files between the 6809 and my linux box. But that means getting SPI working first.

Seems we're all working to something mass storage, OS9 was used on some versions of my first computer, though I never personally used it. I've seen plenty of references to it and have some pretty keen intentions to try it out now...

[lenzjo]

Yes. I've had an initial look at the NitrOS9 repository. That would be awesome to eventually get up and running.
It would certainly promote the desire for a CF (or SD) drive solution.

Indeed. I think it had directories whereas flex didn't, it was a flat file system.

I do have some WD floppy controller chips, and some 5 1/4" floppy drives from the era, but just dropping in a CF card would be much more convenient these days.

They're not 1771's by any chance? I have a couple of them. Haven't looked into it yet, but one of my CF sockets have a 40pin IDE socket and might be usable with the 1771...

Hmm... why is it always: So much I want to do, but only limited time availability. But, we get there eventually. One step at a time!

To true... I seem to get less done now than when I was working and had limited time.

[Editor]

Indeed. I think it had directories whereas flex didn't, it was a flat file system.

Yes. When I see a Flex prompt these days it always brings back long forgotten memories. I do recall with Flex we simply grouped files by "disk", before we had the luxury of directories on later systems. But, it seemed to work perfectly okay at the time, when disks were only SD/SS 40 track capacity anyway?

They're not 1771's by any chance? I have a couple of them. Haven't looked into it yet, but one of my CF sockets have a 40pin IDE socket and might be usable with the 1771...

They are WD1770 FDC chips. I don't recall the WD1771, I'll need to google. I do recall also the WD1772 at the time, which I recall just added stepping advancements over the WD1770, but was otherwise identical.

However, I don't think I really have any immediate plans for pressing my WD1770's into service, as the simplicity of just directly hooking up to the bus, a cheap / relatively tiny CF Card, with no moving parts, seems to win over the nostalgia. Although, there is the need for writing new drivers (over any pre-existing FDC driver code).

To true... I seem to get less done now than when I was working and had limited time.

I hear you. So much to do around the house, and so many maker projects on the go.

And to add to that, this discussion now has me visualising a MECB I/O Card design with a CF socket and perhaps also a PS/2 keyboard interface. Adding these should complete the components I believe MECB would need for porting Flex 9 and making a standalone Flex system.
This perhaps diverges a bit beyond my initial MECB plan of mainly focusing on different CPU Cards and different Peripheral chip Cards, for the purpose of easy experimentation with different CPU and Peripheral device combinations.
But, there is certainly some appeal to perhaps also spending some time on bringing back some early self-contained disk OS system nostalgia. Hmm...

[lenzjo]

And to add to that, this discussion now has me visualising a MECB I/O Card design with a CF socket and perhaps also a PS/2 keyboard interface. Adding these should complete the components I believe MECB would need for porting Flex 9 and making a standalone Flex system.

I have similar reasoning, except as I now have sound on the TMS9118 cardI have taken the sound chip off the I/O card and put the PS/2 iin it's place, though I haven't yet sent off the gerbers. For the "storage" card, I'm mulling around the idea of having both the CF and SD on it along with an RTC for time stamping the files.

This perhaps diverges a bit beyond my initial MECB plan of mainly focusing on different CPU Cards and different Peripheral chip Cards, for the purpose of easy experimentation with different CPU and Peripheral device combinations.

And why not, we have several back planes just lying there doing nothing courtesy of JLCPCB may as well use them. I certainly see a "real" computer along with some smaller "play" computers based on diff CPU's. I'm already getting a little tired of swapping out the CPU cards.

I really have to thank you for MECB Greg. In the past I have always designed SBC's and when I wanted to add something I designed a new SBC. I had thought about using a backplane but it was easier to update an already existing layout. Then I found the MECB with several cards already made and it was just the kick up the rear I needed. I've found it truly liberating from my old way of thinking.

[Editor]

I really have to thank you for MECB Greg. In the past I have always designed SBC's and when I wanted to add something I designed a new SBC. I had thought about using a backplane but it was easier to update an already existing layout. Then I found the MECB with several cards already made and it was just the kick up the rear I needed. I've found it truly liberating from my old way of thinking.

Thank you immensely for this feedback. It means a lot!

This is exactly what I intended with MECB. i.e. Easy mix & match of different Card functions, to support our experimentation.
Also, this is exactly what I intended by sharing what I'm doing via my YT channel and Blog / Forum etc. i.e. That this might also interest or benefit other enthusiasts, who share the same passion.

Creating a community and sharing with others, who have the same interest, is the icing on the cake. Hopefully, with the input of other "like minded" enthusiasts, we all benefit.

I have similar reasoning, except as I now have sound on the TMS9118 card I have taken the sound chip off the I/O card and put the PS/2 in it's place, though I haven't yet sent off the gerbers. For the "storage" card, I'm mulling around the idea of having both the CF and SD on it along with an RTC for time stamping the files.

Since we're getting a bit off-topic (in the VDP topic thread), I've just created a new topic here: MECB Mass Storage and/or Keyboard Interface Card

As I've noted, my current PS/2 Keyboard interface thinking is amounting to about 5x TTL IC's. So, if you've already played with retro PS/2 interfacing, I'd be interested to hear your more about your approach (before I get myself too deep into it). Although, of course, there are always many different ways of rolling the dice. Perhaps I'll see you over at the new topic?

[bugeyedcreepy]

I really have to thank you for MECB Greg. In the past I have always designed SBC's and when I wanted to add something I designed a new SBC. I had thought about using a backplane but it was easier to update an already existing layout. Then I found the MECB with several cards already made and it was just the kick up the rear I needed. I've found it truly liberating from my old way of thinking.

Thank you immensely for this feedback. It means a lot!

This is exactly what I intended with MECB. i.e. Easy mix & match of different Card functions, to support our experimentation.
Also, this is exactly what I intended by sharing what I'm doing via my YT channel and Blog / Forum etc. i.e. That this might also interest or benefit other enthusiasts, who share the same passion.

Creating a community and sharing with others, who have the same interest, is the icing on the cake. Hopefully, with the input of other "like minded" enthusiasts, we all benefit.

You guys keep on talking now, don't stop, y'all hear! I have coat tails to ride!!

In all honesty though, I did much the same (but without all the knowhow) and sought out a project and community I could get behind, so I too signed up to MECB as my modern day 8-bit goto platform, I do believe this will go far (not to jinx you up front though, Brian)...

[epaell]

Great work @lenzjo!

I like the idea of having the sound chip on the VDP board - they seem naturally paired. As it was I had to remove the sound chip from my I/O card because I needed to use the PIA B-port that the sound chip was connected to (for other experiments relating to the storage side of things).

Nice back plane too - the idea of having the reset switch, power LED and activity LEDs there is really useful (particularly when debugging).

[lenzjo]

Great work @lenzjo!

thx @epaell, sorry about the late reply, I've been in hospital with DVT for the last 4 or so weeks. Just got out on Thursday and have been catching up with all I've missed.

I like the idea of having the sound chip on the VDP board - they seem naturally paired. As it was I had to remove the sound chip from my I/O card because I needed to use the PIA B-port that the sound chip was connected to (for other experiments relating to the storage side of things).

Nice back plane too - the idea of having the reset switch, power LED and activity LEDs there is really useful (particularly when debugging).

Glad you like 'em In case you missed it, I've got all my cards/gerbers etc. on Github. Before going into hospital I sent off some gerbers to jlcpcb so expect to see some new/updated stuff in the coming week.

[epaell]

I've been in hospital with DVT for the last 4 or so weeks.

Oh no! I hope you're OK and had a full recovery!

I'll definitely have a look at your GitHub ... although, I'd have to admit that I'm not really set up for SMD (as it is, I'm struggling enough just trying to read the component values on the through hole devices ).

[Editor]

... I've been in hospital with DVT for the last 4 or so weeks. Just got out on Thursday and have been catching up with all I've missed.

I trust they have sorted it out, and you are now well on the way to a full recovery. Take care and be sure to look after yourself, first and foremost!