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. ;D
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
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.
Thanks Bryce, appreciate that...expect a PM shortly ;D
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
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 :D ).
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
Heh, good one mate... Enjoy :)
Also, a CPC on a carpet. Boy, does it bring back memories!
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! :D 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.
Quote from: Gryzor
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. ;D
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...
Excellent work, congratulations!
I'm not patient enough to build such a device myself... ;D
I bet nobody can pick the difference between mine & the original...almost like identical twins... ::)
I see the difference!.... I used a warmer flash on my camera :)
Bryce.
Quote from: Bryce on 22:31, 19 March 12
I see the difference!.... I used a warmer flash on my camera :)
And your logo is missing as well. ;)
Nice work, 00WReX!
Actually the logo is really cool!
Thanks, I drew it myself waaaaay back using AutoCAD 9.0 as far as I can remember :D
Bryce.
After seeing Badstarr's "DIY MegaFlash (Rainbow Spaghetti Edition) Complete!"
Quotehttp://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
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.
I just wish my wire-wrap prototypes looked that good! :-[
Oh, a MegaROM. Have lost count of the devices...
It's a sad day when any CPC expansion becomes ho-hum...the more the merrier :D ;D :D
Cheers,
Shane