Mini-Disk Cable
JC
connectors when building a 34-pin mini-disk multi-cable for the TRS-80
Model I Level II? I'd rather not open the drives up and attempt to
jumper them (mine, in fact, may be hard-wired).
I'd like to construct a mini-disk multi-cable for the Model I Level II
and have only been able to locate a brief discussion of the missing
pin requirement for the drive 0 connector (via the SVD website).
Thus far I've managed to create a 34-pin multi-cable for my 2 drive
system (Mini-Disk System 26-1160 & 26-1161) with what I assume is the
proper keying on the drive 0 connector. When I connect the 1160 by
itself, it appears to respond properly to the poke 14304,1 command and
lights up and spins for a few seconds. If I connect both drives, both
light up and spin for a few seconds. I suspect my cable isn't quite
right.
Any help would be appreciated.
Knut
Hi
You need to pull the pins out from the side of the cable, before putting
together the IDC plugs. If your cable is already made then you need to take it
apart again. I definitely prefer jumpering to the keyed cable, and I have done
that with my 26-1160 & 26-1161. The drives will of course also work with a keyed
cable but only in the correct place.
The pins you need are the
DS0 pin 10
DS1 pin 12
DS2 pin 14
DS3/Side pin 32
If you like, for modern drives DS3 is pin 6 and unused on the model-I pull that too.
So the pin-pulled trick removes those pins that don't apply,
for the EI no pins pulled
for drive :0 connector pull 12, 14, 32
for drive :1 connector pull 10, 14, 32
for drive :2 connector pull 10, 12, 32
for drive :3 connector pull 10, 12, 14
My drives (26-1160 & 26-1161) can't be :3 they don't use pin 32 only 10, 12 and
14. There are only 3 jumpers.
BTW The older EI has interconnected 32 and 34 this is not good. 34 is a disk
change (driven by the drive) signal on modern drives while 32 is side select
(driven by the EI). Though these signals are open collector style so no
electrical conflict happens the effect of a modern drive activating pin 32 might
give strange results. I always cut that link but here you can fix it by pulling
pin 34. Model-I and the older drives do not use 34.
Knut
JC
> JC wrote:
> > On a related note, does anyone know how to 'key' the mini-disk
> > Model I Level II? I'd rather not open the drives up and attempt to
> > jumper them (mine, in fact, may be hard-wired).
>
> > and have only been able to locate a brief discussion of the missing
> > pin requirement for the drive 0 connector (via the SVD website).
>
> > system (Mini-Disk System 26-1160 & 26-1161) with what I assume is the
> > proper keying on the drive 0 connector. When I connect the 1160 by
> > itself, it appears to respond properly to the poke 14304,1 command and
> > lights up and spins for a few seconds. If I connect both drives, both
> > right.
>
> > Any help would be appreciated.
>
> Hi
>
> together the IDC plugs. If yourcableis already made then you need to take it
> apart again. I definitely prefer jumpering to the keyedcable, and I have done
> that with my 26-1160 & 26-1161. The drives will of course also work with a keyedcablebut only in the correct place.
>
> The pins you need are the
> DS0 pin 10
> DS1 pin 12
> DS2 pin 14
> DS3/Side pin 32
>
> If you like, for modern drives DS3 is pin 6 and unused on the model-I pull that too.
>
> So the pin-pulled trick removes those pins that don't apply,
>
> for the EI no pins pulled
> for drive :0 connector pull 12, 14, 32
> for drive :1 connector pull 10, 14, 32
> for drive :2 connector pull 10, 12, 32
> for drive :3 connector pull 10, 12, 14
>
> My drives (26-1160 & 26-1161) can't be :3 they don't use pin 32 only 10, 12 and
> 14. There are only 3 jumpers.
>
> BTW The older EI has interconnected 32 and 34 this is not good. 34 is a disk
> change (driven by the drive) signal on modern drives while 32 is side select
> (driven by the EI). Though these signals are open collector style so no
> electrical conflict happens the effect of a modern drive activating pin 32 might
> give strange results. I always cut that link but here you can fix it by pulling
> pin 34. Model-I and the older drives do not use 34.
>
>
> - Show quoted text -
Thank you for the timely and detailed response. I'd like to toss in a
couple of follow up questions if you have the bandwidth.
For starters (and prior to my original posting), I took a quick peek
inside the 26-1160 and the jumper option didn't leap out at me - thus
the keyed cable strategy. Can you provide a quick how-to on the
jumpered approach? Specifically, where is the jumper block located
and is it pretty straightforward to implement? I haven't been able to
locate any schematics on either the 26-1160 or 26-1161. Also, if I go
with the jumpered solution, then it sounds like a straight up 34-pin
cable (minus the modern 'twist') should suffice.
Second, do I need to key all 4 connectors or can I simply implement
the first 2 connectors for drives 0 and 1 and have the cable end at
the drive 1 IDC plug?
John
Knut
JC wrote:
> On Oct 3, 5:35 am, Knut <kr-l...@nogarbage.online.no> wrote:
>> JC wrote:
>>> On a related note, does anyone know how to 'key' the mini-disk
>>> connectors when building a 34-pin mini-disk multi-cablefor the TRS-80
>>> Model I Level II? I'd rather not open the drives up and attempt to
>>> jumper them (mine, in fact, may be hard-wired).
>>> I'd like to construct a mini-disk multi-cablefor the Model I Level II
>>> and have only been able to locate a brief discussion of the missing
>>> pin requirement for the drive 0 connector (via the SVD website).
>>> Thus far I've managed to create a 34-pin multi-cablefor my 2 drive
>>> system (Mini-Disk System 26-1160 & 26-1161) with what I assume is the
>>> proper keying on the drive 0 connector. When I connect the 1160 by
>>> itself, it appears to respond properly to the poke 14304,1 command and
>>> lights up and spins for a few seconds. If I connect both drives, both
>>> light up and spin for a few seconds. I suspect mycableisn't quite
>>> right.
>>> Any help would be appreciated.
>> Hi
>>
...
>>
>> for the EI no pins pulled
>> for drive :0 connector pull 12, 14, 32
>> for drive :1 connector pull 10, 14, 32
>> for drive :2 connector pull 10, 12, 32
>> for drive :3 connector pull 10, 12, 14
>>
...
>
> Thank you for the timely and detailed response. I'd like to toss in a
> couple of follow up questions if you have the bandwidth.
>
> For starters (and prior to my original posting), I took a quick peek
> inside the 26-1160 and the jumper option didn't leap out at me - thus
> the keyed cable strategy. Can you provide a quick how-to on the
> jumpered approach? Specifically, where is the jumper block located
> and is it pretty straightforward to implement? I haven't been able to
> locate any schematics on either the 26-1160 or 26-1161. Also, if I go
> with the jumpered solution, then it sounds like a straight up 34-pin
> cable (minus the modern 'twist') should suffice.
There are at least two different possible drives inside the 26-1160. Mine is
26-1160A and I think the A is because it has a 240V powersupply (from/for UK).
My drive is a Teac FD-50A and it has 3 jumpers just next to the connector "DS"
and "3 2 1". It is 35 track only. The 26-1160 does have the terminator resistor
block and one jumper installed at DS 1. The 26-1161A is the same drive but
jumpered with "DS 2" instead and has no terminator resistor block.
The other make, if it is like the Texas Peripherals that comes from my model III
does not have a jumper block but a place where tracks can be cut (1 to 4). You
might not want to do that so the cable trick might be your best choice.
I see in the model III manual there is also a drive with a "Shunt E1" that might
be similar to the drive from my model 4 where there is a socket with some leads
across. Originally there probably was a thing for cutting unwanted links. In
every case they are close to the connector.
The cable should be straight for *all* (I think) other computers than the IBM PC
and compatibles...
> Second, do I need to key all 4 connectors or can I simply implement
> the first 2 connectors for drives 0 and 1 and have the cable end at
> the drive 1 IDC plug?
Just leave out any plug you don't need...
Note that :0 should be at the end of the cable because the 26-1160 should have
the terminator.
Note also that because the terminating business is done properly the cable can
be pretty long, if you like, no need to make it short. (The IBM PC and
compatibles do not terminate properly, as all drives terminate. So the cable
needs to be short, if there is more than one drive, for it to work.)
Knut
turnkit
Great response Knut. This makes a great reference on drive connecting
for anyone in the future too. Thanks.