2031LP 75161 wiring question

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2031LP 75161 wiring question

Jim Brain

On this portion of the 2031LP schematic:

ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif

The DC pin for the 75161 is not shown.  Does anyone know what it is connected to?

Jim

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Re: 2031LP 75161 wiring question

André Fachat

Am 4. August 2018 8:14:03 AM schrieb Jim Brain <[hidden email]>:

> On this portion of the 2031LP schematic:
>
> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
>
> The DC pin for the 75161 is not shown.  Does anyone know what it is
> connected to?


Here's the schematic for the 1541 IEEE488 refit http://www.6502.org/users/andre/cbmhw/ieee488/index.html that is basically the same hardware as the 2031.

Hope that helps
André


> Jim
>
> --
> Jim Brain
> [hidden email]
> www.jbrain.com
>

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Re: 2031LP 75161 wiring question

Spiro Trikaliotis
In reply to this post by Jim Brain
Hello Jim,

* On Sat, Aug 04, 2018 at 01:11:37AM -0500 Jim Brain wrote:
> On this portion of the 2031LP schematic:
>
> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
>
> The DC pin for the 75161 is not shown.  Does anyone know what it is connected
> to?

I asked this very same question 11 years ago:

http://www.softwolves.com/arkiv/cbm-hackers/12/12224.html

Even Bild Herd answered there. ;)

You want to create a 1541 to 2031LP conversion board, don't you?

I tried that back then, but never finished the project. The EAGLE files
are still on my HD, though.

Regards,
Spiro.

--
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Re: 2031LP 75161 wiring question

Christian Dirks
In reply to this post by Jim Brain
Hio Jim,
the 4031 schematics, which should be the same for the digital part,
shows that pin 11 is connected to +5V.

I will upload them to zimmers asap.

Christian

Am 04.08.2018 um 08:11 schrieb Jim Brain:

> On this portion of the 2031LP schematic:
>
> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
>
> The DC pin for the 75161 is not shown.  Does anyone know what it is
> connected to?
>
> Jim
>
> --
> Jim Brain
> [hidden email]
> www.jbrain.com
>

--
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2. Stellv. Vorsitzender
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Re: 2031LP 75161 wiring question

William Levak
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Re: 2031LP 75161 wiring question

William Levak
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Re: 2031LP 75161 wiring question

Mike Stein

----- Original Message -----
From: "William Levak" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, August 04, 2018 1:48 PM
Subject: Re: 2031LP 75161 wiring question


On Sat, 4 Aug 2018, William Levak wrote:
...
> I opened up my 2031. The chips are TI SN75160N and SN75161AN. The only
data sheet I could find was for the SN75161B, which apparently has a
different pinout.
--------------------------

FWIW, my 2031LP and HP drives both use TI SN75160AN and SN75161AN ICs.

As far as I can tell, in the LP pins 11, 12 and 19 of the '161 are all n/c.

What's different in the pinouts? At a fast glance the '161B data sheet seems to match the 2031 p.12r schematic exactly; did I miss something?

m




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Re: 2031LP 75161 wiring question

Jim Brain
In reply to this post by André Fachat
On 8/4/2018 1:24 AM, André Fachat wrote:

Am 4. August 2018 8:14:03 AM schrieb Jim Brain [hidden email]:

> On this portion of the 2031LP schematic:
>
> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
>
> The DC pin for the 75161 is not shown.  Does anyone know what it is
> connected to?


Here's the schematic for the 1541 IEEE488 refit http://www.6502.org/users/andre/cbmhw/ieee488/index.html that is basically the same hardware as the 2031.

Hope that helps
André


> Jim
>
> --
> Jim Brain
> [hidden email]
> www.jbrain.com
>

It does, thank you.  Is this on zimmers?

JIm

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Re: 2031LP 75161 wiring question

Jim Brain
In reply to this post by Spiro Trikaliotis
On 8/4/2018 2:41 AM, Spiro Trikaliotis wrote:

> Hello Jim,
>
> * On Sat, Aug 04, 2018 at 01:11:37AM -0500 Jim Brain wrote:
>> On this portion of the 2031LP schematic:
>>
>> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
>>
>> The DC pin for the 75161 is not shown.  Does anyone know what it is connected
>> to?
> I asked this very same question 11 years ago:
>
> http://www.softwolves.com/arkiv/cbm-hackers/12/12224.html
>
> Even Bild Herd answered there. ;)
/me hangs head in shame.  It was late, and I assumed the question was so
esoteric a search would be fruitless.
>
> You want to create a 1541 to 2031LP conversion board, don't you?
>
> I tried that back then, but never finished the project. The EAGLE files
> are still on my HD, though.
I think I am recreating what you were attempting, a combo unit.  I will
put my files up today so you can look at them.

Jim

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Re: 2031LP 75161 wiring question

Jim Brain
In reply to this post by Christian Dirks
On 8/4/2018 4:56 AM, Christian Dirks wrote:
> Hio Jim,
> the 4031 schematics, which should be the same for the digital part,
> shows that pin 11 is connected to +5V.
Thanks.  I added that connection.

Jim

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Re: 2031LP 75161 wiring question

Jim Brain
In reply to this post by William Levak
On 8/4/2018 12:48 PM, William Levak wrote:

> On Sat, 4 Aug 2018, William Levak wrote:
>
>>
>> My copy shows it connected to pin 20.  However, it does not show pins
>> 11, 12, and 19.
>>
>> I did not find a data sheet. It does not appear to be the same as the
>> TI SN75161.
>
> I opened up my 2031. The chips are TI SN75160N and SN75161AN. The only
> data sheet I could find was for the SN75161B, which apparently has a
> different pinout.
Can you link to the conflicting sheets?  I can only find sheets that do
not conflict.

Jim

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Re: 2031LP 75161 wiring question

William Levak
On Sat, 4 Aug 2018, Jim Brain wrote:

> On 8/4/2018 12:48 PM, William Levak wrote:
>> On Sat, 4 Aug 2018, William Levak wrote:
>>
>>>
>>> My copy shows it connected to pin 20.  However, it does not show pins 11,
>>> 12, and 19.
>>>
>>> I did not find a data sheet. It does not appear to be the same as the TI
>>> SN75161.
>>
>> I opened up my 2031. The chips are TI SN75160N and SN75161AN. The only data
>> sheet I could find was for the SN75161B, which apparently has a different
>> pinout.
> Can you link to the conflicting sheets?  I can only find sheets that do not
> conflict.
You're right. I was looking at the wrong pinout.  Data sheets are at:

www.ti.com/lit/ds/symlink/sn75160b.pdf
www.ti.com/lit/ds/symlink/sn75161b.pdf

[hidden email]
SDF Public Access UNIX System - http://sdf.lonestar.org
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Re: 2031LP 75161 wiring question

MiaM
In reply to this post by André Fachat
Den Sat, 04 Aug 2018 08:24:05 +0200 skrev André Fachat <[hidden email]>:

>
>
> Am 4. August 2018 8:14:03 AM schrieb Jim Brain <[hidden email]>:
>
> > On this portion of the 2031LP schematic:
> >
> > ftp://www.zimmers.net/pub/cbm/schematics/drives/old/2031/page-12r.gif
> >
> > The DC pin for the 75161 is not shown.  Does anyone know what it is
> > connected to?
>
> Here's the schematic for the 1541 IEEE488 refit
> http://www.6502.org/users/andre/cbmhw/ieee488/index.html that is
> basically the same hardware as the 2031.

I wounder how hard it would be to change the rom to use PB4 instead of
PB0 for ATN ack (and therefore also move another signal as all pins are
used)?

PB4 is the pin used for ATN ack on a 1541 and in 1541 mode the pinout
needs to be the default for all turbo loaders, copy protection stuff
and similar to work. But I don't know of any copy protection or "turbo
load" software for 2031LP, so there might not be any incompatibles.

By swapping PB4 and PB0 the same ATN trap circuit could be used both in
serial and in IEEE-488 mode.



Btw it would be nice to get rid of the 75160/75161 and replace them
with something else.

Even though they are still available, they seem to not be that common.
For example TME (one of the larger sellers in Europe) only has 75161
and not 75160 unless I'm mistaken. For someone ordering a bunch and
selling a bunch of ready made conversion kits, like Jim seems to be
planning, this might not be a problem. But for everyone who like me
would rather just build a one-off thing it would be nice to be able to
use whatever is more easily obtained or even something that usually
already exists in an electronics hobby component box.

It seems like the 74AC/ACT family can sink/source 24mA, while the
75160/75161 can sink/source 48mA. Every other 74xx family is worse at
drive and/or sink. But the 74AC/ACT family might not be a good choice
as the cmos input protection diodes will load the bus when the unit
containing AC/ACT circuits is powered off. So in practice the 74xx
family could probably be ruled out, unless several bipolar IC's is
piggy backed.

What does the IEEE-488 standard actually spec? And what is the actual
electrical data on Commodore hardware? It seems like the 75160/75161
loads the bus with up to 3,2mA when the bus is low, and up to 2,5mA
when the bus is high.

For something to be really usable in a PET/CBM setup, I think a
reasonable minimum system would be 3-4 devices. For example a PET, an
8080/8250 drive and a 1541 converted to 2031LP, and room for one more
device.

As I understand it, a 74F245 should be able to drive six 75160/75161
inputs.

Ref:
http://www.ti.com/lit/sg/sdyu001ab/sdyu001ab.pdf

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Re: 2031LP 75161 wiring question

Jim Brain
On 8/5/2018 12:29 PM, Mia Magnusson wrote:
>
> I wounder how hard it would be to change the rom to use PB4 instead of
> PB0 for ATN ack (and therefore also move another signal as all pins are
> used)?
Well, in my design, it's trivial, as it is merely:

assign ieee_bus_ack = b[4];

instead of

assign ieee_bus_ack = b[0];

But, the ROM code needs to be altered as well (I know, Mr. Obvious, but
for the rest of the folks)
>
> PB4 is the pin used for ATN ack on a 1541 and in 1541 mode the pinout
> needs to be the default for all turbo loaders, copy protection stuff
> and similar to work. But I don't know of any copy protection or "turbo
> load" software for 2031LP, so there might not be any incompatibles.
>
> By swapping PB4 and PB0 the same ATN trap circuit could be used both in
> serial and in IEEE-488 mode.
Hmm, not really, as I will be implementing the trap circuit in the CPLD
for the IEEE side, so I wouldn't care about the IEC ATN trap circuit.
>
>
> For someone ordering a bunch and
> selling a bunch of ready made conversion kits, like Jim seems to be
> planning, this might not be a problem. But for everyone who like me
> would rather just build a one-off thing it would be nice to be able to
> use whatever is more easily obtained or even something that usually
> already exists in an electronics hobby component box.
Well, Digikey has both in stock.  Farnell or other EU sellers don't?
>
> It seems like the 74AC/ACT family can sink/source 24mA, while the
> 75160/75161 can sink/source 48mA.
I'd look at ABT and ABTH, which can source/sink the right amount. But,
the '245 transceivers, which seems a reasonable fit, are more expensive
than the 75160/161.  Your point on unpowered loading still applies, no
doubt.

Jim