New Hardware Projects

[sirmorris]

Yeeha! Now that's what I'm talkin' about!

The boards I've made came from another user - details on page 7 - schematics etc from the megaupload link a couple of messages back - the 'no-inversar' version.

There's no composite output from this board, which is something I'd like to address. I don't think 3 transistors are going to add significantly to the cost

I make my own boards where possible but once things get serious then I use a board house. Have you seen the zxmmc thread? Anyway back on topic - here's the pix from last night's action:

(slideshow)
http://img217.imageshack.us/g/dscf4248z.jpg/

(Individual)
1. This shows the trimmed UV sensitive PCB material after it's been exposed through the mask, on the right, and developed.
http://img217.imageshack.us/i/dscf4248z.jpg/

2. Here the board has been in the etchant for a few seconds. See how the copper has gone all 'new penny' coloured.
http://img130.imageshack.us/i/dscf4251.jpg/

3. 20 or so minutes into the process and the copper has nearly been eaten away. There are only a couple of small islands left.
http://img217.imageshack.us/i/dscf4254l.jpg/

4. Done! All washed and ready for drilling. The spots are water drops on the reverse side.
http://img810.imageshack.us/i/dscf4257y.jpg/


I'll follow up with some action shots Hot drilling and soldering action.

C

[Moggy]

Hi sir Mo

How is the MMC project progressing?

Regards Moggy

[Andy Rea]

excellent, work Charlie, yes i have seen the mmc thread it's come a long way in 2 years i dare say it's starting to look like a professional job, something that back in the day people would i'm sure have been happy to spend mega bucks on.

you could easily make it composite output you just need to add an emmiter follower with say a 1K resistor in the base and connect it to the output of that circuit labeled 2 which goes to the modulator, the modulator is pretty much expecting a composite signal anyway.

Regards Andy

P.s... oh i just looked at that other page, the circuit is based on mine i even get a mention

[sirmorris]

Hi sir Mo

How is the MMC project progressing?

Regards Moggy

I have had a very hard time with it. A lot of frustration before Christmas coupled with me spending 3 weeks away has meant that at least a month has gone by and I haven't touched it.

However today I set up all the kit at work and I intend to spend at least an hour a day working at it!

Which reminds me - I need to go and solder some keyboard connection ...

Be right back

[sirmorris]

excellent, work Charlie, yes i have seen the mmc thread it's come a long way in 2 years

Indeed. I'm at the final hurdle, but it's quite high

you could easily make it composite output you just need to add an emmiter follower with say a 1K resistor in the base and connect it to the output of that circuit labeled 2 which goes to the modulator, the modulator is pretty much expecting a composite signal anyway.

I'll do that.

P.s... oh i just looked at that other page, the circuit is based on mine i even get a mention

Hehe yes I know It was quite a (welcome) shock to see you back again after reading of your work only the day before ...!

[sirmorris]

Here's the result of a lunchtime's poking into the inner workings of the 1st prototype zxmmc2. The one with the discrete logic.

The green balloon shows the outboard (i.e 'shadow') ROM being enabled for a period when it shouldn't be. There isn't any other bus activity at this time so clashes shouldn't be an issue, but it's not right.

Apart from that I don't have a clue what's happening. I'll be trying to re-acquaint myself with all the little details that I've forgotten about in the time away from the project ;(

brainhurt.jpg

logic trace

(159.17 KiB) Downloaded 1713 times

[Andy Rea]

Doh... it's not right, another look at your logic, if you can remeber what it was supposed to be doing. Keep at it i'm sure you'll crack it

[sirmorris]

... and back to the video board

I fancied some solder fumes for pudding.
http://img651.imageshack.us/i/dscf4261e.jpg/

Mmm. Fumes.
http://img824.imageshack.us/i/dscf4258o.jpg/

[Andy Rea]

Looking good, hope it's trouble free when it comes to testing.

Regards Andy