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Old 01 March 2008, 02:53   #1
aquanaut
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A500 - Two drives on same internal flat cable. Possible?

Hello,

The title says it all. I've tried with Two drives, one jumpered as DF0 and the other one jumpered as DF1 but just df0 was detected.

Does the cable need a twist somewhere or if possible at all, is there any kind of trick?

Thanks in advance.
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Old 01 March 2008, 08:48   #2
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The trick, you need a motor enable-flipflop and the rdy pulse generation logic that are commonly found in external drives. Then you need to wire DS1 from the CIA chip to the circuitry you have created.

The A500 does not have the required circuitry to support an extra drive on the motherboard, so you need to add them.

Aminet doc/hard has several projects on making your own external drives. Start from there.
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Old 01 March 2008, 12:34   #3
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Hi aquanaut:

I'm guessing you're going for dual internal floppies or you'd just connect an external drive..?

FWIW:
Being a bit of a butcher I'd dismantle an external unit & wire it into the back of the external floppy connector on your A500...
...there's 'issues' with this approach, of course.
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Old 02 March 2008, 03:15   #4
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Quote:
Originally Posted by Jope View Post
The A500 does not have the required circuitry to support an extra drive on the motherboard, so you need to add them.
I thought that the external unit was just a connection to the disk port and a drive as DF1. I'll stick with a single drive system for now.
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Old 02 March 2008, 03:26   #5
aquanaut
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Quote:
Originally Posted by Charlie View Post
Hi aquanaut:

I'm guessing you're going for dual internal floppies or you'd just connect an external drive..?

FWIW:
Being a bit of a butcher I'd dismantle an external unit & wire it into the back of the external floppy connector on your A500...
...there's 'issues' with this approach, of course.
Hi Charlie,

Yes, you are guessing right. I wanted dual internal floppies because i am fitting an A500 inside an IBM PS/1 case and there's the 5.25" extra bay that i could use to fit another drive if it didn't involve butchering an external unit.

The case is like this one:

http://pozadzides.com/firewall/photos/PS1_Frontal.jpg

I have the mobo and floppy installed, and the case painted black. I already have a pc keyboard and pc mouse adapter. Now i just need to route the ports to the back, fit a pc psu and connect the leds.
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Old 02 March 2008, 19:18   #6
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Hmmm, interesting project.
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Old 02 March 2008, 20:35   #7
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Quote:
Originally Posted by aquanaut View Post
I thought that the external unit was just a connection to the disk port and a drive as DF1. I'll stick with a single drive system for now.
Look inside the external unit. You'll find two 74 series logic chips on a little board in there. These are needed for DF1 to work. In big box amigas, the same kind of logic is on the motherboard and it is enabled by setting a "df1 enable" jumper. On the A500/600/1200, there's only enough logic on the motherboard for DF0: and nothing more.
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Old 03 March 2008, 00:51   #8
aquanaut
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Quote:
Originally Posted by Charlie View Post
Hmmm, interesting project.
I created a post about it here:

http://eab.abime.net/showthread.php?p=399331#post399331

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Old 03 March 2008, 00:55   #9
aquanaut
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Quote:
Originally Posted by Jope View Post
Look inside the external unit. You'll find two 74 series logic chips on a little board in there. These are needed for DF1 to work. In big box amigas, the same kind of logic is on the motherboard and it is enabled by setting a "df1 enable" jumper. On the A500/600/1200, there's only enough logic on the motherboard for DF0: and nothing more.
I'll see if i can get that done on a perforated board. I'd really like to have another drive without having to butcher an external one

By the way, i created a post about the mod:

http://eab.abime.net/showthread.php?p=399331#post399331
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Old 03 March 2008, 03:53   #10
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Here's an external drive controller board with both sets of logic. I have yet to actually test it but it looks ok to me.

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Old 03 March 2008, 03:56   #11
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What an idiot I am sometimes!
Sorry I haven't added the values of the resistor network or the caps to that schematic yet.
I've seen numerous diagrams now as well where it's been a 74XX38 IC used for the RDY signal logic that needs to be created. (Quad NAND 2 input O/C output).

Last edited by Eclipse; 03 March 2008 at 04:04.
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