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Old 25 November 2005, 00:54   #1
Mr B
Registered User
Join Date: Nov 2005
Location: Sweden
Posts: 749
A600/1200/4000 HD interface mod... how to hook up 4 drives.

Well, triggerd by a question in a thread i was asking things in, i feelt it was time i repayed all the advices i recived, so here goes.

This is the basic build instructions translated from swedish, as best i can, after the description published by a friend of mine, in the swedish publication "AmigaInfo" issue 1 1997. The entier project is on the webpage, and the upfront info is in english, but the actual build description, is in swedish, and this is where my service to you is offerd.

I'll translate. Ask anything you need, if i cant get the answer from the text, i'll try and ask him, that might take a day or two, and he might not remeber the answer anymore :- )

Anyway, here we go. Pin config:

A1200/A4000 IDE IDE0/1 IDE2/3
C= Spec. IDE ("Primary") ("Secondary)
* 1 _RESET o---------+----[ 1]------------[ 1]
2 GND o--------------[ 2]------------[ 2]
3 D7 o--------------[ 3]------------[ 3]
4 D8 o--------------[ 4]------------[ 4]
5 D6 o--------------[ 5]------------[ 5]
6 D9 o--------------[ 6]------------[ 6]
7 D5 o--------------[ 7]------------[ 7]
8 D10 o--------------[ 8]------------[ 8]
9 D4 o--------------[ 9]------------[ 9]
10 D11 o--------------[10]------------[10]
11 D3 o--------------[11]------------[11]
12 D12 o--------------[12]------------[12]
13 D2 o--------------[13]------------[13]
14 D13 o--------------[14]------------[14]
15 D1 o--------------[15]------------[15]
16 D14 o--------------[16]------------[16]
17 D0 o--------------[17]------------[17]
18 D15 o--------------[18]------------[18]
19 GND o--------------[19]------------[19]
20 n/c o--------------[20]------------[20]
21 n/c o--------------[21]------------[21]
22 GND o--------------[22]------------[22]
23 _IOW o--------------[23]------------[23]
24 GND o--------------[24]------------[24]
25 _IOR o--------------[25]------------[25]
26 GND o--------------[26]------------[26]
27 IOCHRDYo--------------[27]------------[27]
*28 n/c o--------------[28]
29 n/c o--------------[29]------------[29]
30 GND o--------------[30]------------[30]
*31 IRQ o---------+-|<-[31]
32 nc o--------------[32]------------[32]
33 DA1 o--------------[33]------------[33]
*34 nc o--------------[34]
35 DA0 o--------------[35]------------[35]
36 DA2 o--------------[36]------------[36]
*37 _IDECS1o--------------[37]
*38 _IDECS2o------------------------------[37]
*39 _ACTIVEo--------------[39] [39]---+

40 GND o--------------[40]------------[40] |

(My personal addition)
For independent channel activity diodes, pin 39 should be connected only on channel
1, from the amiga, and a custom active should be construckted as follows:

39 _ACTIVE2 +5V DC o-----[#####]----------->|------------+
R1 D3

(the data for this is actually in the original pinout, but the deformating made it impossible to understand, so i had to do something.)

The options are to connect both channels to one led, connect only the first channel to a led, and ignore the second, and finaly, to use this custom hookup. there is 5v in pin 41 btw, used to power the drives circutry, there is also 5v in pin 42, but since that is the feed for the drives spindle motor, that might be a bad idea... (the 5v feed is my addition to the whole deal, but its nothing fancy)

Pretty straight forward (im sorry about the looks, seams the font is slightly wrong, and the text was once tab formated. Tried to reformat, by spacing, but apparently "extra" spaces are removed.) But anyhow.

Some explaining then. from here on its my own rambling, ask if there is anything unclear.

As you can se the only real "modifications" are the addition of the 2 diods D1/D2, any generic diod will do just fine, altho lowvoltage signal diods are recomended, aka, the 1N4148, since i cant tell one way from the other on the diod, i can only tell you the marking should be on the main connector, and the other side goes to the diffrent channels. (pin 31), the reset signal is taken from pin 1, to pin 1 and pin 38 on both channels, pin 37 is put to channel 1, on pin 37, and pin 38, is put to channel 2 ON PIN 37.. Remember this, this is a great way to ruin your mod, and possibly your amiga if you dont get this right. The mod for pin 39, with the independant activityleds, is up to you, you can actually provide each drive with its own led, if you want, by hooking it a seperat resistor, and led, powering it of pin 41, and feed it to pin 39, localy on the drive. (but plz, if you do, DONT connect the wire (pin 39) at all in the main connector, it should be ok, but who knows.) Pin 28 is only connected on the first channel, why, i have no idea, since its listed as "n/c" along with a bunch of others, that still are connected all the way.

Im hoping there will be SOME questions on this, to show atleast some intrest, hopefully, i dident mess it up TO bad, by adding a few thoughts of my own. (or translating) The circutry is right, and the translation is "ok" altho, spelling and missunderstandings might take the better part of me, any uncertanty, ASK.

2 2 device cables (3 44 pin connectors)
2 1N4148 or comparable (D1/D2)
(and for the additional activityled/leds)
1 220ohm resistor (R1)
1 generic 5v led, colour by choise (D3)
(not that much hu?)

Best of luck.

Source for the info, for those that feel it relevant, and as a accnowledgement to the fella who did it possible.

Last edited by Mr B; 25 November 2005 at 01:02.
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