DDI-1 DIY

[CraigsBar]

Just for curiosity, what's wrong with zaxon's devices?



I will be making a full list of Bill-of-Materials after the successful prototype testing and, after such demands, I plan to offer them in 3 variants: board only, board + parts for DIY, or already assembled & tested.
Please let me know which of them are you interested in and I will be calculating the final cost afterwards.

Board and parts sounds like fun.

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[Querubin]

Great job.


I will be interested on one diy kit if there haven't got SMD components. If has, a mounted one will be my option.


Waiting the results.

[SilverGreen93]

There are no SMD components in the design. The main chips will be socketed.

[Querubin]

Thanks SilverGreen93.

One board + parts for DIY for me, please.

[SilverGreen93]

I finally assembled the first board.
The ROM works perfectly in both PARADOS and AMSDOS, but I can't seem to get the floppy to work properly.
I always get the "Drive A: is missing" error when accessing any floppy with the CAT / DIR / |A command
Do I need to format the disk in CP/M before use in standard BASIC? Can I format it without using CP/M?
If not, it means that I have to find a PC with a floppy controller to write a CP/M disk first and then test if CP/M boots first.


P.S.: Yes, I have a floppy with ready signal.

[khaz]

You can format with Parados.
|drive
http://www.cpcwiki.eu/imgs/0/0d/Parados.pdf

[SilverGreen93]

You can format with Parados.
|drive
http://www.cpcwiki.eu/imgs/0/0d/Parados.pdf

Thanks a lot! That seems to have done the trick.


So, initial testing looks very promising


Edit: In the second picture, why is ParaDOS showing 4 times on the start screen?

[SilverGreen93]

I tested CP/M also, but I have one problem. It seems that after loading any CP/M program, when returning to CP/M, the error "read fail" occurs and I can never recover.
If I shut off the Amstrad and turn back on, then I can again enter CP/M using the |CPM command. If I return to AMSDOS it works, but if I want to go back to CP/M, it doesn't load, again with the error "read fail".
Something weird is going on. The disk reads fine the first time, but the second time it tried to access it, it gives the read fail error.
Any clues? I don't know if it's something wrong with the components I used or the floppy drive itself is partially bad.


Also, If I CAT the CP/M system disk it works, if I change the disk to standart BASIC one, CAT still works, but if I return to CAT the CP/M disk it again says read fail. This is very weird.


Later edit: If I disconnect the power cable from the floppy and connect it back when pressing Retry it works fine, it reads it again.

[arnoldemu]

Thanks a lot! That seems to have done the trick.


So, initial testing looks very promising


Edit: In the second picture, why is ParaDOS showing 4 times on the start screen?

How are you decoding the ROM index which selects ParaDOS? Are you comparing against all 8 bits?

[arnoldemu]

I tested CP/M also, but I have one problem. It seems that after loading any CP/M program, when returning to CP/M, the error "read fail" occurs and I can never recover.
If I shut off the Amstrad and turn back on, then I can again enter CP/M using the |CPM command. If I return to AMSDOS it works, but if I want to go back to CP/M, it doesn't load, again with the error "read fail".
Something weird is going on. The disk reads fine the first time, but the second time it tried to access it, it gives the read fail error.
Any clues? I don't know if it's something wrong with the components I used or the floppy drive itself is partially bad.


Also, If I CAT the CP/M system disk it works, if I change the disk to standart BASIC one, CAT still works, but if I return to CAT the CP/M disk it again says read fail. This is very weird.


Later edit: If I disconnect the power cable from the floppy and connect it back when pressing Retry it works fine, it reads it again.

I think it'll be doing seeks and recalibrates and read ids to determine the disc format.
Then when it determines the disc format, it then does a read data.

Does that help?

[SilverGreen93]

How are you decoding the ROM index which selects ParaDOS? Are you comparing against all 8 bits?

You can see the schematic in the first pages of this topic. The ParaDOS is mounted in the same place as the AMSDOS.

I think it'll be doing seeks and recalibrates and read ids to determine the disc format.
Then when it determines the disc format, it then does a read data.

Does that help?

No.
But I managed to find another floppy disk drive and with this one it does work. So my conclusion is that the floppy drive was having some problems, but I don't know why.
The first floppy was a TEAC FD-235HF 3823-U5 and now I have replaced it with a NEC FD1231H.
So far all seems good for now with the new drive.

[Duke]

Since Parados is initialized 4 times, some bit is not decoded correctly.
That would be either databit 1 or 2, when doing a rom select, since the 464 only initializes roms 0-7 and basic isn't overwritten (bit 0). I did not study the schematic.

[SilverGreen93]

Since Parados is initialized 4 times, some bit is not decoded correctly.
That would be either databit 1 or 2, when doing a rom select, since the 464 only initializes roms 0-7 and basic isn't overwritten (bit 0). I did not study the schematic.

This is strange because the AMSDOS is initialized only once.
Anyway, the problem seems to have been fixed after replacing the 74LS136 with a 7486 chip.

[Duke]

This is strange because the AMSDOS is initialized only once.
Anyway, the problem seems to have been fixed after replacing the 74LS136 with a 7486 chip.

AMSDOS is silent though, so it would not be obvious unless you check the rom space.
EDIT:
You could put maxam on and check the upper roms 0-7 to look for any mirrors.
Or just check from basic ? himem

[IanS]

Anyway, the problem seems to have been fixed after replacing the 74LS136 with a 7486 chip.

Not a good idea, the 136 is used specifically because it has open-collector outputs, and the 3 outputs used by the rom number decode are tied together. With an 7486 the outputs will be fighting each other.

[SilverGreen93]

Not a good idea, the 136 is used specifically because it has open-collector outputs, and the 3 outputs used by the rom number decode are tied together. With an 7486 the outputs will be fighting each other.

Yeah, I know, but now it works. Maybe I had a faulty one. Until I get new parts, I will continue to use the 7486. Although, if I look at the schematic I think the only "damage" that can be made is to the 7486 itself, due to the tied outputs of the 3 decoder gates.

LE: On a second thought, this may impact also the functionality. Anyway, the exact parts should arrive from TME next week.

[SilverGreen93]

All the testing is completed. It works great.

Unfortunately I don't have all the necessary parts yet to make more. I have only 2 complete boards for now.

I plan to ship the first board in January to the first person that sent me a message.

The price will be around 45EUR + shipping. Standard shipping should be around 12EUR to any country in the EU. I will need to quote the final price afterwards.

Due to the fact that not all the parts I found are from the same manufacturer or era, I want to test them before shipping to make sure you don't get a faulty one, so I might ditch the DIY part and sell only fully assembled and tested ones.

If this is ok with you all guys, I will keep you posted about the progress.


P.S.: I can also sell them without the D765 and FDC9229BT if anyone wants them like that or already has those parts, because those are the parts I am mostly short of right now.

[CraigsBar]

All the testing is completed. It works great.

Unfortunately I don't have all the necessary parts yet to make more. I have only 2 complete boards for now.

I plan to ship the first board in January to the first person that sent me a message.

The price will be around 45EUR + shipping. Standard shipping should be around 12EUR to any country in the EU. I will need to quote the final price afterwards.

Due to the fact that not all the parts I found are from the same manufacturer or era, I want to test them before shipping to make sure you don't get a faulty one, so I might ditch the DIY part and sell only fully assembled and tested ones.

If this is ok with you all guys, I will keep you posted about the progress.


P.S.: I can also sell them without the D765 and FDC9229BT if anyone wants them like that or already has those parts, because those are the parts I am mostly short of right now.

I'd rather have the kit for the fun of soldering it myself. But if that is no longer available the  I am still interested in an assembled board.

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[Querubin]

Congratulations!.

No problem if you assemble it.

One question for all. Colud be used an expansion cable for this?. How long it could be?

[SilverGreen93]

Congratulations!.

No problem if you assemble it.

One question for all. Colud be used an expansion cable for this?. How long it could be?

Well, in theory you could try, but keep it very short.
In practice, it is NOT recommend to use any cable. This will probably result in unreliable behavior and/or data corruption.

[Querubin]

Ok, Thanks.

[SilverGreen93]

Happy Holidays guys!


Here are some photos of my final CPC464 setup.
I've made a dual-floppy-drive unit, using some cardboard and solid core wire to make hooks to hold it in place on an angle on the CPC case.
Both floppies are modded with wires to provide the READY signal and they are both powered from the DDI-1 interface.


I've also made a gamepad from a SNES controller and a Parallel Centronics adapter for printer.
And of course, an SCART/CGA to VGA adaptor from ebay to hook it up an LCD monitor.

[Querubin]

Merry Christmas.


Great! Hope have mine soon.

[CraigsBar]

Merry Christmas.


Great! Hope have mine soon.

me too, Now I am reliving my first computer with my newly restored CPC 464 I need a floppy drive for it LOL.

[SilverGreen93]

Just wanted to update you on the status of this project.


I'm still waiting for a couple of components to arrive (D765s and EPROMs). Meanwhile, I need to finish my exams and then I will write a short documentation with pictures for how to assemble the KIT yourself. After publishing it here, I will start shipping for the first units . Hopefully this month.


Cheers.


PS.: Meanwhile, anyone that wants it can add himself to the list here (click the link): https://docs.google.com/spreadsheets/d/1GleRhKIo71r2kXYFSYJaaIWSvXhHe1CcnDU0wpnyp_w/edit?usp=sharing
Fingers crossed, no spammers. I will contact each one of you through private message. And I will update the list with shipping dates.