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Spectrum user needing help in this Amstrad world.

Started by Rorschak, 14:11, 03 July 22

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Hi, i'm a 40 year Spectrum user with a faily deep knowledge of the speccys hardware.
I've decided to dip my feet into this other flavour of Z80 goodness.

I've bought a non working CPC 464 and a recreated 270100 CPC 464, which i'm slowly building.

I've fairly proud of my google-fu skills, but they have let me down a couple of times...

1. The broken CPC 464 is the last revision Z80329/MC0099A, and i can't for the life of me find a schematic for this board.
2. I managed to find gatearrays in Spain at, which i thought would be the toughest part of the new build. The one component i can't find is the joystick port... The footprint is not easy to find. Does anyone have a part number for at compatible part?

The broken 464 gives me a ram error on bit 1. It doesn't matter if i change the ramchips (TMS4464), the error persists. I'm not even sure which of the two chips contains bit 1. I've ruled out broken traces and soldersplashes, so i kinda need the schematics to proceed.

The rest of the machine seems to work fine.

The attached picture is my current progress on the new 464...


Hi, welcome to the CPCWiki!

On the amendment service manual ( you can find some info on the MC0100 board of the 6128, which is the one that also uses a new SMD Gate Array.

Unfortunately, looking at the pictures of the board (, it seems that they are connected directly to the gate array, so if your ram chips are good, then maybe the gate array is damaged and the only way to fix it is get a new one.

Do you have some 4164 at hand, or can you test your ram chips for faults?


I do have 4164 chips, but as someone thought it would be a good idea to fill the holes for the 4164s with solder, it's gonna take a while to mount them.
I don't think that the 4464 ram is faulty though, as i get the same error on bit one when i swap the two ram chips.
Thanks, i'll take a look at the MC0100 schematics.


what do you mean with "The broken 464 gives me a ram error on bit 1"? 

How do you test this?

roy bates

im not sure why your  trying to get it working without the suport logic in place,like the 74ls153's
or  a fully populated board


Quote from: roy bates on 13:12, 04 July 22im not sure why your  trying to get it working without the suport logic in place,like the 74ls153's
or  a fully populated board
Because that's not the board they're talking about.


You misunderstand. I have two CPC 464s. The blue one from the original picture is a first revision 464 than i'm building a little at a time. Thats the one that needs a joystick socket. I'm nowhere near ready to test that machine yet. I've also realised that i need an older case for it, one where the keyboard is wired and not split in two membrane connectors.

The one with the ram error is shown in this picture. As you can see, i've replaced the rom with Noel Llopis' diagnostic rom. It reports a ram error where bit 1 does not return the expected value.

You cannot view this attachment.

This picture is from the diagnostic rom Wiki, my machine only has a red stripe next to bit 1.

You cannot view this attachment.


Google "DB9 male PCB connector" should show you where to get a suitable joystick connector.


That was the very first search i tried. I haven't been able to find any connectors with that footprint.
Every single PCB connector i have found has the anchor pins next to the data pins. The one needed for the first revision of the 464 has the anchor pins in front of the data pins.
I think it would be easier to simply get a couple of 90 degree brackets and use a DB9M made for cable use.

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