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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 20th Feb 2020, 11:32 pm   #121
John Earland
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Default Re: Commodore PET 3016

Hi, couldn’t wait. Everything is fine! I just had a thought-I’ve been connecting the buzzer to the top terminals... but it should have been the bottom ones! It worked. However, the buzzer I bought from eBay is no good-although I can hear the Space Invaders sound effects I also get a continuous bleep. I have a smaller buzzer that came with an Arduino kit and that worried perfectly! Although it is very quiet so I guess I’ll need an amplifier. I don’t know what type to get-any ideas? J
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Old 20th Feb 2020, 11:34 pm   #122
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Default Re: Commodore PET 3016

Just seen your post-you are absolutely right! You’re a genius!
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Old 20th Feb 2020, 11:49 pm   #123
SiriusHardware
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Default Re: Commodore PET 3016

If you are looking at amplified sound, bear in mind that the amplifier will have to run on some sort of power supply, either a 9V battery or perhaps 5V taken from the PET's own internal power supply.

Here's a mono amplifier which includes an integral volume setting control:

https://www.ebay.co.uk/itm/LM386-DC-...K/254423474295

For any module like that, you will also need a conventional (low impedance) speaker to connect it to. Maybe you already have one.

You can also buy a mono amplifier kit complete with a speaker, which would be a good project to give you a little bit more experience with soldering:

https://www.kitronik.co.uk/2165-mono...ersion-30.html

Note the above kit has a fixed gain (no volume control) so you would have to experiment with resistor values or add a volume control yourself.
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Old 21st Feb 2020, 12:19 am   #124
SiriusHardware
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Default Re: Commodore PET 3016

You may also get louder sound out from your Arduino sounder if you drop the value of your series resistor to a lower value, try 470 ohms or 1K instead of 10K.
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Old 21st Feb 2020, 8:07 am   #125
John Earland
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Default Re: Commodore PET 3016

Thank you for all of this! I shall give it a go!
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Old 21st Feb 2020, 10:26 pm   #126
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Default Re: Commodore PET 3016

Hi guys, I think I’m going to have a panic attack!
I was messing about with sound and now it’s all gone haywire! I type in BASIC commands and it returns ?SYNTAX ERROR. I think I’ve done something seriously wrong to it! Help!
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Old 21st Feb 2020, 10:57 pm   #127
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Default Re: Commodore PET 3016

I found this on the web:
SYNTAX ERROR on every command and screen scrolling problems: I read of a case where on every command entered the system reacted with a "SYNTAX ERROR". Also when scrolling the screen, some characters change. This is a problem when the main CPU reads the video screen. When a command is entered, it is read from screen, not from some buffer memory. Also when the screen is scrolled, the data is read from the screen and written back to it. So both problems came from the same source, the bus driver that separated the video RAM from the CPU bus. It had a broken driver in one of the lines.

Any use?
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Old 21st Feb 2020, 11:31 pm   #128
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Default Re: Commodore PET 3016

I think to get to a position of sanity you are really going to have to get those sockets changed first because the behaviour of the machine was unpredictable to begin with.

When you asked about trying out your sound add-on I did almost say that when making modifications or adding things to any sort of system you really need to start with the system in full working order, otherwise if something weird happens, you don't know whether it was your mod / add-on that caused it, or whether it was going to happen anyway.

Try to be patient, get those sockets replaced and if there are still outstanding problems after that then at least they will be consistent and you should be able to fault find it more logically.

Almost all of the connections on the user port connector go back to the second 6520, so if you really feel your experiments have caused this latest behaviour try changing the second 6520 to see if that makes a difference. It might, but at the present time there's no way of knowing whether it is the chip or its socket which is causing this behaviour.
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Old 21st Feb 2020, 11:46 pm   #129
John Earland
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Default Re: Commodore PET 3016

You are quite right. I’m getting them changed next week!
I swapped on of the 2114s actually. Seemed to do the trick but as you say-who knows!!
Thank you for saving my sanity!
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Old 22nd Feb 2020, 11:09 pm   #130
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Default Re: Commodore PET 3016

Whilst I’m waiting for the sockets to be replaced I would like to start thinking about the sound issue though. Although I can download from a tape it doesn’t seem to be saving them. I’ve tried 2 different commodore tape machines-both allow the PET to download software but not save programs I’ve written. Could the problem be connected since they are sound problems? Just thinking ahead!
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Old 23rd Feb 2020, 2:40 am   #131
SiriusHardware
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Default Re: Commodore PET 3016

The CASS_WRITE signal on pin E5 of the cassette connectors JP3 and JP6 and on pin 7 of the user port appears to originate from the 'user port' 6520 pin 13 (PB3). You could try checking that the connection between that IC pin and those three connector terminals is intact, as it should be.

I'm not familiar enough with PETs to know whether the CASS_WRITE signal is a digital data stream which is converted into audio tones inside the cassette unit, or whether the CASS_WRITE signal is TTL-level audio tones. Does anyone know?
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Old 23rd Feb 2020, 8:21 am   #132
TonyDuell
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Default Re: Commodore PET 3016

Cass_write is essentially a TTL level signal that drives the record head (after a bit of simple analogue processing). The cassette unit is very simple inside.
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Old 23rd Feb 2020, 10:13 am   #133
John Earland
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Default Re: Commodore PET 3016

Thanks guys. Is the 6520 likely to be the one furthest away from the keyboard connector? I call that the first one!
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Old 23rd Feb 2020, 11:23 am   #134
SiriusHardware
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Default Re: Commodore PET 3016

Yes, but from what Tony says you are looking for a data signal from CASS_WRITE rather than an audio signal.
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Old 23rd Feb 2020, 1:20 pm   #135
John Earland
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Default Re: Commodore PET 3016

Quote:
Originally Posted by TonyDuell View Post
Cass_write is essentially a TTL level signal that drives the record head (after a bit of simple analogue processing). The cassette unit is very simple inside.
Thanks Tony. I shall test the connections-what ohm setting would you recommend?
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Old 23rd Feb 2020, 1:21 pm   #136
John Earland
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Default Re: Commodore PET 3016

Quote:
Originally Posted by SiriusHardware View Post
Yes, but from what Tony says you are looking for a data signal from CASS_WRITE rather than an audio signal.
Thanks for all your help! Iíve really enjoyed this! I real learning curve for me and Iím still on it!!
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Old 25th Feb 2020, 9:14 am   #137
John Earland
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Default Re: Commodore PET 3016

Quote:
Originally Posted by SiriusHardware View Post
The CASS_WRITE signal on pin E5 of the cassette connectors JP3 and JP6 and on pin 7 of the user port appears to originate from the 'user port' 6520 pin 13 (PB3). You could try checking that the connection between that IC pin and those three connector terminals is intact, as it should be.

I'm not familiar enough with PETs to know whether the CASS_WRITE signal is a digital data stream which is converted into audio tones inside the cassette unit, or whether the CASS_WRITE signal is TTL-level audio tones. Does anyone know?
Hi, I'm taking my board to me friend tonight be though I might check the connections and found the following on 200k ohm setting:
Pin 13 - cassette 5 = 110
Pin 13 - User port 7 = 110
Pin 13 - User port M - 110

Not sure what this tells me but you will know I am sure!
J
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Old 25th Feb 2020, 1:12 pm   #138
John Earland
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Default Re: Commodore PET 3016

Interesting, seems I can save afterall. I am also getting sound again now but intermittently - seems to be fading in and out but with a constant buzz in the background now which it didn't have before. Let's hope the new sockets will sort it out!

J
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Old 25th Feb 2020, 1:55 pm   #139
SiriusHardware
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Default Re: Commodore PET 3016

As you're now so close to getting those sockets replaced I think it best to let that go ahead before attempting any further diagnosis since the machine seems to be randomly rewiring itself, making logical fault finding challenging.

See how that goes first, and then we'll look at any outstanding problems you still have after that. It's always easier to hit a static target than one which is constantly moving.
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Old 5th Mar 2020, 11:37 am   #140
John Earland
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Default Re: Commodore PET 3016

Hi, I have had the sockets replaced. A couple of things:
1. Plugged it in last night and all seemed to work fine. Didn't try the sound though.
2. Switched in on this morning and nothing! I swapped the 6520s around and it worked! I don't think it's got anything to do with them though.
3. I'm running it now to see how it is performing and all seems well.

However, I tried loading a program I saved before the sockets were replaced and although it loads the program, the pet hands a the 'Ready' prompt and I have to switch it off and on. It will load however, ready prepared software e.g. I am playing Space Invaders right now and it loaded first time etc.

It all seems to be working well. I tried the sound again this morning and same isssue. Can you help with the next step? Infuritaing thing is - the sound was working from CB2 well! Could it be a damaged resistor or capacitor somewhere??

Best wishes,
John
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