PET 3032 alive :)

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PET 3032 alive :)

Francesco Messineo
Hi all,
I've just repaired the 3032 electronics (case and all repaint will
require months).
It smoked a tantalum capacitor on first power-on (no, it wasn't
shorted as I tested all of them before powering on), then it showed
the usual random characters screen until I found and replaced two bad
ROMs. It was an easy repair after all, considering that almost all
chips have a 1979 date codes (two of them have a 1978 date code).
I've wired the power transformer for 240V, it was originally wired for
220V, the secondaries give a bit more than 16V AC now and all the
supply rails look fine.
Now I'll test (as time permits) the ports (IEEE, parallel, both tapes).
It was the one where I've found the "super tool" UD3 ROM expansion,
and it's my only PET anyway :)
CRT looks fine too, sharp and bright.
Just happy about it, no questions :)

Frank IZ8DWF

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Re: PET 3032 alive :)

Francesco Messineo
I've spoken too soon :(
Swapping the 6520s gives no cursor and no keyboard input, so I think I
have to find a spare PIA (or design my own PLD version, if I want to
spend some months of spare time doing it).
Does anyone have a 6520 I can buy?

On Thu, Feb 2, 2017 at 1:02 PM, Francesco Messineo
<[hidden email]> wrote:

> Hi all,
> I've just repaired the 3032 electronics (case and all repaint will
> require months).
> It smoked a tantalum capacitor on first power-on (no, it wasn't
> shorted as I tested all of them before powering on), then it showed
> the usual random characters screen until I found and replaced two bad
> ROMs. It was an easy repair after all, considering that almost all
> chips have a 1979 date codes (two of them have a 1978 date code).
> I've wired the power transformer for 240V, it was originally wired for
> 220V, the secondaries give a bit more than 16V AC now and all the
> supply rails look fine.
> Now I'll test (as time permits) the ports (IEEE, parallel, both tapes).
> It was the one where I've found the "super tool" UD3 ROM expansion,
> and it's my only PET anyway :)
> CRT looks fine too, sharp and bright.
> Just happy about it, no questions :)
>
> Frank IZ8DWF

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Re: PET 3032 alive :)

Ethan Dicks
On Thu, Feb 2, 2017 at 9:18 AM, Francesco Messineo
<[hidden email]> wrote:
> Does anyone have a 6520 I can buy?

I think you can get away with a 6821 PIA - those can be easier to find.

-ethan

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Re: PET 3032 alive :)

Francesco Messineo
I do have a few 6821, but I read that the 6520 is equivalent to the
6820. Isn't it?

On Thu, Feb 2, 2017 at 3:55 PM, Ethan Dicks <[hidden email]> wrote:
> On Thu, Feb 2, 2017 at 9:18 AM, Francesco Messineo
> <[hidden email]> wrote:
>> Does anyone have a 6520 I can buy?
>
> I think you can get away with a 6821 PIA - those can be easier to find.
>
> -ethan
>
>        Message was sent through the cbm-hackers mailing list

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Re: PET 3032 alive :)

Gerrit Heitsch
In reply to this post by Francesco Messineo
On 02/02/2017 03:18 PM, Francesco Messineo wrote:
> I've spoken too soon :(
> Swapping the 6520s gives no cursor and no keyboard input, so I think I
> have to find a spare PIA (or design my own PLD version, if I want to
> spend some months of spare time doing it).
> Does anyone have a 6520 I can buy?

I read somewhere that you can also use an 6821, but I'm not 100% sure.
Can anyone confirm or deny it? And if deny, what are the differences?

  Gerrit




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Re: PET 3032 alive :)

Francesco Messineo
Looking at the datasheet, it appears that pin25 of the 6821 is called
E (enable) and on 6820 is the familiar phi2 or pih0. Timings look
compatible (but I didn't quite read all the datasheets), so I might
give it a try and see what I get.

On Thu, Feb 2, 2017 at 3:58 PM, Gerrit Heitsch
<[hidden email]> wrote:

> On 02/02/2017 03:18 PM, Francesco Messineo wrote:
>>
>> I've spoken too soon :(
>> Swapping the 6520s gives no cursor and no keyboard input, so I think I
>> have to find a spare PIA (or design my own PLD version, if I want to
>> spend some months of spare time doing it).
>> Does anyone have a 6520 I can buy?
>
>
> I read somewhere that you can also use an 6821, but I'm not 100% sure. Can
> anyone confirm or deny it? And if deny, what are the differences?
>
>  Gerrit
>
>
>
>
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Re: PET 3032 alive :)

Didier Derny
E on 6821 = phi2 6520

even a 6524 probably works as a replacement of 6520 :)

or  a bulgarian CM602 :)





On 02/02/2017 16:03, Francesco Messineo wrote:

> Looking at the datasheet, it appears that pin25 of the 6821 is called
> E (enable) and on 6820 is the familiar phi2 or pih0. Timings look
> compatible (but I didn't quite read all the datasheets), so I might
> give it a try and see what I get.
>
> On Thu, Feb 2, 2017 at 3:58 PM, Gerrit Heitsch
> <[hidden email]> wrote:
>> On 02/02/2017 03:18 PM, Francesco Messineo wrote:
>>> I've spoken too soon :(
>>> Swapping the 6520s gives no cursor and no keyboard input, so I think I
>>> have to find a spare PIA (or design my own PLD version, if I want to
>>> spend some months of spare time doing it).
>>> Does anyone have a 6520 I can buy?
>>
>> I read somewhere that you can also use an 6821, but I'm not 100% sure. Can
>> anyone confirm or deny it? And if deny, what are the differences?
>>
>>   Gerrit
>>
>>
>>
>>
>>        Message was sent through the cbm-hackers mailing list
>         Message was sent through the cbm-hackers mailing list


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Re: PET 3032 alive :)

Francesco Messineo
On Thu, Feb 2, 2017 at 4:08 PM, Didier Derny <[hidden email]> wrote:
> E on 6821 = phi2 6520
>
> even a 6524 probably works as a replacement of 6520 :)
>
> or  a bulgarian CM602 :)
>

yes, I just tried, 6821 works on both positions on the 3032.
Now both tape interface work fine (after a good cleaning of the connectors).

Thanks for the great hint! I still have a few 6821 around :)

Frank IZ8DWF

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Re: PET 3032 alive :)

Ethan Dicks
In reply to this post by Francesco Messineo
On Thu, Feb 2, 2017 at 9:57 AM, Francesco Messineo
<[hidden email]> wrote:
> I do have a few 6821, but I read that the 6520 is equivalent to the
> 6820. Isn't it?

I'm not positive on a feature-by-feature, bug-by-bug comparison, but
as used in the PET, I'm pretty sure the 6821 is a drop-in.  I've done
it, but I can't promise 100.00% functional compatibility (I can't
recall if my IEEE-488 tests were completely successful or not, but I
think I have bad sockets too).  It won't break anything, but it's
_possible_ there could be something that isn't *exactly* the same.
Since you have the 6821, I'd pop one in and look for your cursor and
keyboard to return.

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Re: PET 3032 alive :)

Ethan Dicks
In reply to this post by Francesco Messineo
On Thu, Feb 2, 2017 at 11:21 AM, Francesco Messineo
<[hidden email]> wrote:
> On Thu, Feb 2, 2017 at 4:08 PM, Didier Derny <[hidden email]> wrote:
>> even a 6524 probably works as a replacement of 6520 :)
>> or  a bulgarian CM602 :)
>
> yes, I just tried, 6821 works on both positions on the 3032.
> Now both tape interface work fine (after a good cleaning of the connectors).

Excellent!

> Thanks for the great hint! I still have a few 6821 around :)

You bet!

-ethan

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Re: PET 3032 alive :)

Francesco Messineo
In reply to this post by Ethan Dicks
On Thu, Feb 2, 2017 at 5:21 PM, Ethan Dicks <[hidden email]> wrote:

> On Thu, Feb 2, 2017 at 9:57 AM, Francesco Messineo
> <[hidden email]> wrote:
>> I do have a few 6821, but I read that the 6520 is equivalent to the
>> 6820. Isn't it?
>
> I'm not positive on a feature-by-feature, bug-by-bug comparison, but
> as used in the PET, I'm pretty sure the 6821 is a drop-in.  I've done
> it, but I can't promise 100.00% functional compatibility (I can't
> recall if my IEEE-488 tests were completely successful or not, but I
> think I have bad sockets too).  It won't break anything, but it's
> _possible_ there could be something that isn't *exactly* the same.
> Since you have the 6821, I'd pop one in and look for your cursor and
> keyboard to return.
>

I'm waiting for a suitable IEEE-488 cable for the PET, so for now I'm
not going to test it.
Anyway, based on the fact that the 488 interface is going only into
UC6, I'll leave the 6821 (a 1983 vintage EF6821P) on UC7 position.

Thanks again!
Frank

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Re: PET 3032 alive :)

Francesco Messineo
And it's dead again :(
I was typing the cbmlink bootstrap basic program.
I saved it on tape and I was trying the first test runs as it just died on me.
Now at reset it clears the video memory and sometimes it displays a
few random characters but most of the time the screen remains just
blank.
I'm going to try to substitute the kernel ROM since on one of my
programmers refuses to read entirely (on another one reads fine every
time).
With no kernel ROM, the screen remains full of characters as it should.
Ok... old hardware isn't so easy to fix after all.
Suggestions welcome of course!
Frank

On Thu, Feb 2, 2017 at 5:28 PM, Francesco Messineo
<[hidden email]> wrote:
>
> I'm waiting for a suitable IEEE-488 cable for the PET, so for now I'm
> not going to test it.
> Anyway, based on the fact that the 488 interface is going only into
> UC6, I'll leave the 6821 (a 1983 vintage EF6821P) on UC7 position.
>
> Thanks again!
> Frank

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Re: PET 3032 alive :)

Gerrit Heitsch
On 02/02/2017 07:32 PM, Francesco Messineo wrote:

> And it's dead again :(
> I was typing the cbmlink bootstrap basic program.
> I saved it on tape and I was trying the first test runs as it just died on me.
> Now at reset it clears the video memory and sometimes it displays a
> few random characters but most of the time the screen remains just
> blank.
> I'm going to try to substitute the kernel ROM since on one of my
> programmers refuses to read entirely (on another one reads fine every
> time).
> With no kernel ROM, the screen remains full of characters as it should.
> Ok... old hardware isn't so easy to fix after all.

Could be a bad RAM. As far as I know, the 3032 uses 2 banks of 4116
DRAMs. You can swap both banks by desoldering and then crossing 2
resistors. If it's RAM, that should make the system behave differently.
Which ones? For that I would need the schematics... Anyone have them?


  Gerrit



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Re: PET 3032 alive :)

Gerrit Heitsch
On 02/02/2017 08:26 PM, Gerrit Heitsch wrote:

> On 02/02/2017 07:32 PM, Francesco Messineo wrote:
>> And it's dead again :(
>> I was typing the cbmlink bootstrap basic program.
>> I saved it on tape and I was trying the first test runs as it just
>> died on me.
>> Now at reset it clears the video memory and sometimes it displays a
>> few random characters but most of the time the screen remains just
>> blank.
>> I'm going to try to substitute the kernel ROM since on one of my
>> programmers refuses to read entirely (on another one reads fine every
>> time).
>> With no kernel ROM, the screen remains full of characters as it should.
>> Ok... old hardware isn't so easy to fix after all.
>
> Could be a bad RAM. As far as I know, the 3032 uses 2 banks of 4116
> DRAMs. You can swap both banks by desoldering and then crossing 2
> resistors. If it's RAM, that should make the system behave differently.
> Which ones? For that I would need the schematics... Anyone have them?

If the schematics at

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001N/320349-6.gif

fit your board, it would be R41 and R42 which you'd have to cross to
swap the banks.

  Gerrit



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Re: PET 3032 alive :)

Francesco Messineo
On Thu, Feb 2, 2017 at 8:30 PM, Gerrit Heitsch
<[hidden email]> wrote:

> On 02/02/2017 08:26 PM, Gerrit Heitsch wrote:
>>
>> On 02/02/2017 07:32 PM, Francesco Messineo wrote:
>>>
>>> And it's dead again :(
>>> I was typing the cbmlink bootstrap basic program.
>>> I saved it on tape and I was trying the first test runs as it just
>>> died on me.
>>> Now at reset it clears the video memory and sometimes it displays a
>>> few random characters but most of the time the screen remains just
>>> blank.
>>> I'm going to try to substitute the kernel ROM since on one of my
>>> programmers refuses to read entirely (on another one reads fine every
>>> time).
>>> With no kernel ROM, the screen remains full of characters as it should.
>>> Ok... old hardware isn't so easy to fix after all.
>>
>>
>> Could be a bad RAM. As far as I know, the 3032 uses 2 banks of 4116
>> DRAMs. You can swap both banks by desoldering and then crossing 2
>> resistors. If it's RAM, that should make the system behave differently.
>> Which ones? For that I would need the schematics... Anyone have them?
>
>
> If the schematics at
>
> http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001N/320349-6.gif
>
> fit your board, it would be R41 and R42 which you'd have to cross to swap
> the banks.
>
Thanks for the suggestion. I'm going to try also with the pettester
kernel that I just downloaded and written to a 2532. If I don't get a
better clue, I'll swap the resistors in a few minutes.
Frank

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Re: PET 3032 alive :)

Francesco Messineo
On Thu, Feb 2, 2017 at 8:32 PM, Francesco Messineo
<[hidden email]> wrote:

>>
> Thanks for the suggestion. I'm going to try also with the pettester
> kernel that I just downloaded and written to a 2532. If I don't get a
> better clue, I'll swap the resistors in a few minutes.


The pettester.bin image gave two alternating screens, one with all the
characters and one full of g. It means all ram is testing good
according to the program.
Swapping the kernel rom with an eprom has no effect also. More work
needed on this board :(

Frank

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RE: PET 3032 alive :)

Baltissen, GJPAA (Ruud)
In reply to this post by Francesco Messineo
Hallo Francesco,


> Does anyone have a 6520 I can buy?

I have over 30 of them laying around. You can have some just for P&P. Your address, please.

Regarding the 6821: I have replaced the 6520 by a 6821, and the other way around, and didn't have any problems. But as said before: no guarantee.


Met vriendelijke groet / With kind regards,
Ruud Baltissen

www.Baltissen.org



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