Has anybody Connected 2 Floppy drives to a DDI-1 clone (Zaxon)

[Audronic]

Hi All

Has anybody Connected 2 Floppy drives to a DDI-1 clone made by Zaxon
As a 1 Drive setup mine works perfectly BUT 2 drives, i have a range of problems.


Thanks    Ray

[Audronic]

Bump

[ZbyniuR]

You don't said what kind trouble you have, but for exemple:
If you use Parados and you put normal 178K disc in drive B it makes read error.

[Audronic]

@ ZbyniuR

Hi ZbyniuR

Would it be possible for you to do a test for me on a DDI-1 Compatible (Zaxon DDI-1)
With 2 720K Floppy drives connected (I have used two Sony MPF-920)Using Zaxon Mods.
One configured as Drive 0 and the other configured as drive 1

1) Parados - AMSDos switch in AMSDos position
2) ABBA Switch in Normal Position A=0  B=1
3) Place in both drives Formatted disks (40 Track Single sided)
   With some thing on them EG Drive0.bas and on the Other Drive1.bas.
   to help identify which drive is being read.
4) Log on Drive (|a) and do a CAT (OK for me)
5) Log on Drive (|b) and do a CAT (OK for me)

6) With the disks still in the drives Switch the ABBA switch to the other position.

7) Log on Drive (|a) (1) and do a CAT (OK for me)

Log on Drive (|b) (0) and do a CAT (FAILS with a read fail)

9) If i remove the disk from the A drive (1) and do a CAT (|b) (0) it reads OK ??.

I am up to the point of believing it is trying to read BOTH drives after you do a
|B (1) CAT.

I have had a look with a logic probe and i think that the original (AMSTRAD) design
does not support ABBA switches due to the way that they select the drives. ??

I have changed a few drives during this test and several rebuilds of cables.
I also have substituted the 74LS83 with a 7400 as a test (Still the same)

The wiring is correct on my DDI-1.

If your tests get the same results then "that's the way it is".

It has been an interesting journey.


Thanks   Ray

[CraigsBar]

That's the way it is I'm afraid. Although removing the disc is probably not necessary. I just need to (r)etry  on my 6128+ in that scenario.

[Audronic]

@ CraigsBar

Ok Thanks

I am looking at doing this:-

https://www.dropbox.com/s/u6uclsl7ceijd1k/DDI-1%20Clone%20%28Rays%20MOD%29.jpg?dl=0

I can not work out how to put this in the Message ??


Thanks    Ray

[Bryce]

How is your setup handling the ready signals? If you've just set Ready permanently, then it can and will confuse the drives.

Bryce.

[Audronic]

@ Bryce


I am using the Modification as suggested by Zaxon to enable pin 34 to indicate Ready ( Wire from Pin 34 before trace cut wired to Disk change switch on drive)
as Both drives are loaded with disks then the pin 34 is always active, ?? is the CPC wanting disk change on 34 or a Ready signal ??.

The drives i am using are the ones recommended by Zaxon Sony MFP-920 ( one of them was modified by him ( Drive 0 )and the other by me ( Drive 1 ))
If you know of a 3.5" floppy drive that i could use to replace the Sony MFP-920's I may have some here.

Your point about " Ready signals " has me thinking.   "drats".

Thanks       Ray

[CraigsBar]

IMHO the best drives for CPC use are Samsung SFD 321B. Not only are they very easy to mod to provide a real ready signal, but the are easily found on ebay. I bought a brand new one a month or so ago for less than 4 euro (6 euro with shipping from Germany) one link to desolder and resolder for the swap from DC to RDY. The links are even labelled on the PCB, so you cannot do it wrong lol.

[Audronic]

@ CraigsBar


Thanks, I don't have any Samsung SFD 321B's
I will have a look on EBay.


So we require a true Ready Signal  - Not a Disk Change on pin 34. ?


Thanks     Ray

[Bryce]

@ Bryce


I am using the Modification as suggested by Zaxon to enable pin 34 to indicate Ready ( Wire from Pin 34 before trace cut wired to Disk change switch on drive)
as Both drives are loaded with disks then the pin 34 is always active, ?? is the CPC wanting disk change on 34 or a Ready signal ??.

The drives i am using are the ones recommended by Zaxon Sony MFP-920 ( one of them was modified by him ( Drive 0 )and the other by me ( Drive 1 ))
If you know of a 3.5" floppy drive that i could use to replace the Sony MFP-920's I may have some here.

Your point about " Ready signals " has me thinking.   "drats".

Thanks       Ray

The ready signal may be causing the problem. The DS0: and DS1: signals are what choose which drive is being "spoken" to. You should check that both of these are not low at the same time, otherwise both drives will try to answer. I assume you have modified the drives to answer to the correct DS signal?

Bryce.

[Audronic]

@ Bryce


Yes I have confirmed that the drives are DS0 for one and DS1 for the other.
I will have a look at the " Ready " Signal as compared to the Drive change signal that is on Pin 34.


PS:-  The way that DDI-1 (Amstrad) originally selected drives is a bit suspect thats why i am having a look at driving the lines another way.


Thanks    Ray

[Bryce]

The original DDI-1 didn't go 100% to the standard, which can confuse things slightly, but it does set DS0 and DS1 correctly for each drive. The standard used two bit binary to select a total of four drives, the DDI-1 uses just one bit and should always send a 0 to one and a 1 to the other drive (as selected).

Bryce.

[Audronic]

@ All

Thanks for all the help with the Floppy drives.
I have made up 2 Drives that only have Ready applied to pin 34 and the problem does not go away.
So i will have to assume that ""  that's the way it is ""


I will have a look at another way of making it work (Later).


Thanks again     Ray

[Audronic]

Fixed

http://www.cpcwiki.eu/forum/hardware-related/faulty-ddi-1-(zaxon)/msg166088/?topicseen#msg166088



Ray