Just built a MegaReset ! ***UPDATED*** Now officially a MegaROM

[00WReX]

On the weekend just gone I thought I'd have a go at building a MegaROM just for fun. 

I have no PCB making facilities or much else other than a half decent soldering iron so it was always going to look ugly.

And because I don't have an EPROM programmer, it cannot test it out either...but I'll get to test it one day I'm sure. 

I have plugged it in and the CPC did not lock up or die and the onboard reset button I added works, so it cannot be too bad...

So at the moment I have the worlds most complex CPC reset button.

Cheers,
Shane

[Bryce]

Hi 00WReX,
       wow, it looks fantastic! Very neatly wired. I assume you have a plan to get an EPROM to try it out. If you don't have any local solution, let me know and I can send you one.
There are a few things you can do to test the circuit without an EPROM: For example, setting Jumper 2 (ROM 0) to "on" should make the CPC freeze on start. If the CPC freezes then about 80% of the circuit is working as it should.

Bryce.

[00WReX]

Thanks Bryce, appreciate that...expect a PM shortly 

Also thanks for the tip with regard to the ROM 0 jumper. I tried it and it worked exactly as expected, causing the CPC to cyclic reboot
only displaying the boot prompt up until it attempts to load BASIC...then reboot. And while I was at it I tried it on both a 464 & 6128.
While it is doing this if I flip the jumper back to the off position the CPC boots to the Ready prompt as normal.

While assembling the MegaROM I was continually performing continuity checks with my multi meter.
And once completed I did an end to end continuity check on all parts of the circuit that included a bridge.

So far so good  .

Cheers,
Shane

[00WReX]

OK, a huge thanks to Bryce.
Firstly for the fantastic Wiki page detailing the MegaROM.
Secondly for burning me an EPROM so that I could test out my MegaROM ( formerly a MegaReset    ).

I am very excited to say that it worked perfectly, all ROMS test fine & even moving the onboard EPROM size jumper & ROM 0 jumper (BASIC)
functioned as expected.

Below are a couple of photo's to show it in action...also the last photo shows my modified ROM 0 (BASIC v1.23 with an OK... prompt instead of Ready).

I also added a green "power on" LED since the original photo...

TFM will also be happy that I kept my word...and not only do I have FutureOS on the MegaFlash...I got Bryce to put it onto the MegaROM EPROM for me 

Thanks again Bryce. 

Cheers,
Shane

[Gryzor]

Heh, good one mate... Enjoy


Also, a CPC on a carpet. Boy, does it bring back memories!

[Bryce]

I'm seriously impressed. You're the first (as far as I know) to have built their own MegaROM from my instructions AND IT WORKED! So my description obviously isn't as crap as I thought it was? Are there any details missing from the Wiki page that would have made it easier? You'll probably use it quite a bit from now on, because there's something satisfying about using hardware that you built yourself

Bryce.

[00WReX]

Also, a CPC on a carpet. Boy, does it bring back memories!

Haha...yeh, my permanently setup CPC is a Schneider on my desk with the centronics connectors & the MegaFlash connected.
So I grabbed a CPC out of the cupboard to test out the MegaROM with the edge connector...could have walked a few more paces and put it on the dining table...but in such a rush to test it, I basically put it straight down on the carpet. 

Bryce, the details on the wiki were excellent...otherwise theres no way mine would have worked (I would not have even attempted it).
If I had the stuff to make a PCB it would have been really simple...the way I did it was a little time consuming.
Once I get something in my head, I have to give it a go otherwise it will bug me.
I also received today a CPC464 MC0099A motherboard (the really tiny one) that I plan to use in a custom case of some kind...

Shorting pins 1 & 3 on the tape connector and it all fired up nicely...

[robcfg]

Excellent work, congratulations!


I'm not patient enough to build such a device myself... 

[00WReX]

I bet nobody can pick the difference between mine & the original...almost like identical twins...

[Bryce]

I see the difference!.... I used a warmer flash on my camera

Bryce.

[MaV]

I see the difference!.... I used a warmer flash on my camera

And your logo is missing as well.

Nice work, 00WReX!

[Gryzor]

Actually the logo is really cool!

[Bryce]

Thanks, I drew it myself waaaaay back using AutoCAD 9.0 as far as I can remember

Bryce.

[00WReX]

After seeing Badstarr's "DIY MegaFlash (Rainbow Spaghetti Edition) Complete!"

http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/diy-megaflash-(rainbow-spaghetti-edition)-complete!/

I decided I want to give it a go as well. But before that I wanted to have another go at a MegaROM.
After my first MegaROM, I immediately wanted to do another one as I realised I could make the top of the board a lot neater (not necessarily the bottom of the board though). Basically I wanted to have all the wiring on the underside.
So over the last couple of nights I made version 2 of the MegaROM...still totally based on Bryce's design.
Then next I will give the MegaFlash a go.

Any tips from Badstarr or Bryce ? (I will be using the same method / technique as this latest MegaROM...so very messy underneath).

cheers,
Shane

[Bryce]

The only further suggestion/advice I could give you, would be to use solid core wire. This will allow you to define the routing on the bottom and make things a bit neater.

Bryce.

[Zetr0]

I just wish my wire-wrap prototypes looked that good! 

[Gryzor]

Oh, a MegaROM. Have lost count of the devices...

[00WReX]

It's a sad day when any CPC expansion becomes ho-hum...the more the merrier 

Cheers,
Shane