Commodore PET 3016 - Page 11 - UK Vintage Radio Repair and Restoration Discussion Forum

John Earland · 6th Apr 2020, 8:17 pm

Its just very strange though. The games doesn't freeze and we don't have to switch the machine off, it simply makes a loud beep, then the games resets at zero! The highest score etc. is retained! Very odd.

julie_m · 6th Apr 2020, 8:27 pm

They're available online (the source code of every PET emulator necessarily contains a copy). Perhaps someone with a suitable programmer can extract the relevant files and burn you a set of EPROMs? (Or a single chip to replace all four; in which case you'll have to bend up 3 pins, and solder two wires {for the top two address lines} and four diodes {to create an AND gate for the chip enable lines} to certain places on the motherboard; one of the diodes is especially tricky but if you can do that, you can do anything!)

John Earland · 6th Apr 2020, 8:59 pm

I think the EPROMS might be a good place to start-I do know someone but they live in Canada! He’s done it before for me though.

SiriusHardware · 6th Apr 2020, 10:21 pm

Um, let's see, so the original PROMs were removed and are no longer available? That's a pity. I have a bad feeling that they may have had a non-standard footprint, and if so there are only a very small subset of EPROM types which can directly replace those.

Let's assume John's expansion board uses more sensible, replaceable devices. If that's the case maybe the better line of attack would be to try to replicate / replace the contents of the devices on that PCB - most likely it already does what Julie suggested, uses a bigger more modern EPROM device with its own address decoder which jumps in whenever the address range of the missing onboard PROMs is accessed.

But: Are we really sure this is a hardware problem? Julie says there are PET emulators around, try loading the game into one of those and see if you can replicate that behaviour with the game running under the emulator. It would be a bit silly to tear the machine apart again if the real problem is just a bug in the game software.

John Earland · 6th Apr 2020, 11:26 pm

Yes-that’s a good idea. I’ll take a look for some emulators. I also have a tapuino- I’m waiting for a micro sd card writer to arrive. I could download a tap version to see if that is any better.

John Earland · 15th Apr 2020, 10:51 am

I've been using the Tapuino successfully for over a week. Works beautifully on both the PET and Commodore 64. The game problem above does not seem to happen so it was obviously a glitch in that particular piece of software and/or an issue with the loading from tape.

I have decided to purchase the SD2IEC unit from Tynemouth Software as a disk replacement - tapuino is great but it's a pain to access -so I can leave this in situ without having to move the PET -so I am hoping for a happy experience!

SiriusHardware · 15th Apr 2020, 11:24 am

I'm pleased the PET turned out to be blameless, it's been through quite a lot lately.

John Earland · 15th Apr 2020, 3:17 pm

I spoke too soon! The SD2PET FUTURE device arrived. I plugged it into the PET and it lights up as it should etc. But, when I type in any commands to access the Disk Drive such as CATALOG, DIRECTORY, SAVE "TEST",8 or LOAD "*",8 the machine just hangs there and freezes.

I tried it without the SD2PET attached and I get the same response so I thought it might be a ROM BASIC 4.0 issue. I'm using the Tynemouth Software ROM/RAM board so I switched to BASIC 2.0 and tried LOAD "$",8 but again, the same issue - it freezes. So I'm guessing again, that the ROM is likely to be okay.

Also, without the device attached, when I try to access it via a command I had expected to see '?DEVICE NOT PRESENT' but I don't.

Can anyone help?

SiriusHardware · 15th Apr 2020, 3:51 pm

I can't help you with this one unfortunately. If you are sure you are using it as intended then it could possibly be faulty from new, maybe the party who sold you it would be best placed to advise you on how to proceed.

Even people who know PETs won't necessarily have any experience of using one of these as it's non-original, third party hardware.

It would be interested to see some images of it, what's the storage medium? SD cards, or USB storage perhaps?

Is this a PET only item, or is it C64 compatible as well like your other gadget? If it is, what happens if you try it with the C64?

John Earland · 15th Apr 2020, 4:14 pm

I don't think this is a device issue. I think this is PET issue. The problems occur even when the device is not attached. The PET just freezes everytime the IEEE port is trying to be accessed - even if there is nothing attached. I expected to see the '?DEVICE NOT PRESENT' when trying to access the port without anything attached but I don't. It just freezes. I think this is a potential IC issue leading out to the IEEE port. What do you think?

SiriusHardware · 15th Apr 2020, 4:38 pm

Unfortunately this is so far outside my personal experience I can't really offer specific advice.

I take it your TAPDUINO connects to the tape port and pretends to be a tape machine, so that wasn't connected to the IEEE port?

Do you have any other hardware which is designed to be connected to that port?

John Earland · 15th Apr 2020, 4:44 pm

Yes - the TAPUINO connects to the tape port and that continues to work. I don't have anything else. Apart from the cost (£85!) I would really like the Disk to work. I'm looking at the IEEE Schematics but not sure what I'm looking at!! LOL - I shall keep plodding away.

Thanks anyway - if it wasn't for you, I wouldn't have had the machine running in thw first place!
J

SiriusHardware · 15th Apr 2020, 4:46 pm

I see your friends at Tynemouth software also do something called a 'Pet Diagnostics Module' which plugs into the CPU socket and analyses various aspects of the machine, but they do not include loopback tests on the various ports, which is a pity.

I really would just contact them first regarding your problems with this unit (which I also saw on the website) and they may be able to shed some light - don't forget to mention that the machine already has their other add-on Gizmo in it, the one with the offboard PROM / Memory etc. They (more than anyone ) will know what you should be expecting to see when there is nothing plugged in.

John Earland · 15th Apr 2020, 4:49 pm

Quote:

Originally Posted by SiriusHardware

I see your friends at Tynemouth software also do something called a 'Pet Diagnostics Module' which plugs into the CPU socket and analyses various aspects of the machine, but they do not include loopback tests on the various ports, which is a pity.

I really would just contact them first regarding your problems with this unit (which I also saw on the website) and they may be able to shed some light - don't forget to mention that the machine already has their other add-on Gizmo in it, the one with the offboard PROM / Memory etc.

It is a pity because it would have been worth a try!

Kyle__B · 15th Apr 2020, 6:49 pm

Quote:

Originally Posted by SiriusHardware

Even people who know PETs won't necessarily have any experience of using one of these as it's non-original, third party hardware.

It would be interested to see some images of it, what's the storage medium? SD cards, or USB storage perhaps?

Is this a PET only item, or is it C64 compatible as well like your other gadget? If it is, what happens if you try it with the C64?

A lot more people are going to know about these gadgets than you think. Floppy drives have fell very severely out of fashion with the commodore scene. All old computers really, but especially commodores because of how bulky and annoying those drives are.

It's an SD device and only for the PET series, Commodore's home computers used a different type of port. Not to mention with Commodore the model of drive itself is usually A) only capable of working on one computer family and B) only reads it's own disks...

This is very much a problem with the computer itself but I don't have a PET to hand. I think you might have to go to a computer forum.

SiriusHardware · 15th Apr 2020, 6:50 pm

John, I would still suggest you contact TS to see if they recognise your symptom, they might very well say "Oh yes! That's because... all you have to do is..."

If you exhaust that avenue and are still convinced you have a hardware fault with the PET and not the new hardware...

This (attached) is the circuit of the IEEE interface. At the heart of it is a 6520, 'C6', presumably IC6. I don't know if your PCB has the IC numbers identified on the PCB. Also involved are A10 (7417) F1 (74LS08) and A7, A8, A9 (MC3446 * 3).

If all of these ICs are now in sockets, look for the obvious things first, take each of those ICs out one at a time and make sure none of the pins got folded over by accident when they were reinserted after the sockets were replaced.

If there is no obvious problem there You could try, if possible, replacing
C6 (6250)
A10 (7417)
F1 (74LS08)

The ones above are the ones you are likely to have already, or which will be easier to find. Note the 7417 probably -has- to be a 7417, not a 74LS17.

If you had a full set of spare ICs available or money to burn I would suggest replacing A10 (7417) and A7, A8, A9 (All MC3446) first, since these are the devices most exposed to the outside world and with the greater likelihood of being damaged by external dark forces. Unfortunately those MC3446 ICs are pretty exotic (therefore expensive) ICs.

You could order just one and try it in each of the three positions to see if it fixes your problem but - that would be a gamble as there is no guarantee that only one of the original ICs is damaged - could be more.

One good thing about those is that there are three of them so you can do resistive / voltage level comparisons of each one against the other two to see if there are any obvious differences between any one of them and the other two. We'll get to that after you've tried the easier things, starting with a 6520 swap (I have the impression you have a few of those).

Kyle_B - Comments acknowledged and of course other forums / fora exist, but John hasn't done too badly so far here. I don't know that we can definitely say the PET is at fault when the drive device has never been seen working.

SiriusHardware · 15th Apr 2020, 7:30 pm

I found this interesting info on, where else but Tynemouth Software's website.

http://blog.tynemouthsoftware.co.uk/...rt-faults.html

It mentions that the keyboard 6520 is also involved in some aspects of the IEEE port.

Kyle__B · 15th Apr 2020, 8:34 pm

I was working on the theory that PETs will tell you off if you try to access a device that's not there, rather than just locking up.Without one to compare with you might have to check that behavior with an emulator.

If it's as stupid as my first C64 then it could just be something as simple as a bad contact somewhere. I know I had to twist that thing at the corners to get it's datasette to work.

John Earland · 15th Apr 2020, 10:21 pm

Thanks guys-I have 8 6250s and have tried them all with the same result. Even when nothing is attached the PET simply locks. As I’ve mentioned I was expecting to see ‘?Device not present’ or something like that and I swear I have seen the machine do this-just not now!! I can’t believe all 8 ICs are faulty but you never know. Someone else mentioned swapping the 6520s but nothing so far. I’ll check all the contacts to make sure they’re clean etc and then take Sirius’s advice and start looking at the other ICs!

John Earland · 15th Apr 2020, 10:42 pm

Quote:

Originally Posted by SiriusHardware

I found this interesting info on, where else but Tynemouth Software's website.

http://blog.tynemouthsoftware.co.uk/...rt-faults.html

It mentions that the keyboard 6520 is also involved in some aspects of the IEEE port.

Thank you for this-a really interesting read. I’ve tried the pokes and peeks
(at least the assert ones) and have found some issues. According to the blog the number returned at peek should be the same as at poke, i.e:
0, 52, 52, 255, 52, 251 but I get:
192, 185, 186, 255, 255, 52

Am I doing something wrong or is this telling me that the PET has IC issues?

6th Apr 2020, 8:17 pm	#201
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 Its just very strange though. The games doesn't freeze and we don't have to switch the machine off, it simply makes a loud beep, then the games resets at zero! The highest score etc. is retained! Very odd.

6th Apr 2020, 8:27 pm	#202
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Commodore PET 3016 They're available online (the source code of every PET emulator necessarily contains a copy). Perhaps someone with a suitable programmer can extract the relevant files and burn you a set of EPROMs? (Or a single chip to replace all four; in which case you'll have to bend up 3 pins, and solder two wires {for the top two address lines} and four diodes {to create an AND gate for the chip enable lines} to certain places on the motherboard; one of the diodes is especially tricky but if you can do that, you can do anything!) __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

6th Apr 2020, 8:59 pm	#203
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 I think the EPROMS might be a good place to start-I do know someone but they live in Canada! He’s done it before for me though.

6th Apr 2020, 10:21 pm	#204
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 Um, let's see, so the original PROMs were removed and are no longer available? That's a pity. I have a bad feeling that they may have had a non-standard footprint, and if so there are only a very small subset of EPROM types which can directly replace those. Let's assume John's expansion board uses more sensible, replaceable devices. If that's the case maybe the better line of attack would be to try to replicate / replace the contents of the devices on that PCB - most likely it already does what Julie suggested, uses a bigger more modern EPROM device with its own address decoder which jumps in whenever the address range of the missing onboard PROMs is accessed. But: Are we really sure this is a hardware problem? Julie says there are PET emulators around, try loading the game into one of those and see if you can replicate that behaviour with the game running under the emulator. It would be a bit silly to tear the machine apart again if the real problem is just a bug in the game software.

6th Apr 2020, 11:26 pm	#205
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 Yes-that’s a good idea. I’ll take a look for some emulators. I also have a tapuino- I’m waiting for a micro sd card writer to arrive. I could download a tap version to see if that is any better.

15th Apr 2020, 10:51 am	#206
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 I've been using the Tapuino successfully for over a week. Works beautifully on both the PET and Commodore 64. The game problem above does not seem to happen so it was obviously a glitch in that particular piece of software and/or an issue with the loading from tape. I have decided to purchase the SD2IEC unit from Tynemouth Software as a disk replacement - tapuino is great but it's a pain to access -so I can leave this in situ without having to move the PET -so I am hoping for a happy experience!

15th Apr 2020, 11:24 am	#207
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 I'm pleased the PET turned out to be blameless, it's been through quite a lot lately.

15th Apr 2020, 3:17 pm	#208
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 I spoke too soon! The SD2PET FUTURE device arrived. I plugged it into the PET and it lights up as it should etc. But, when I type in any commands to access the Disk Drive such as CATALOG, DIRECTORY, SAVE "TEST",8 or LOAD "",8 the machine just hangs there and freezes. I tried it without the SD2PET attached and I get the same response so I thought it might be a ROM BASIC 4.0 issue. I'm using the Tynemouth Software ROM/RAM board so I switched to BASIC 2.0 and tried LOAD "$",8 but again, the same issue - it freezes. So I'm guessing again, that the ROM is likely to be okay. Also, without the device attached, when I try to access it via a command I had expected to see '?DEVICE NOT PRESENT' but I don't. Can anyone help? Last edited by John Earland; 15th Apr 2020 at 3:24 pm.*

15th Apr 2020, 3:51 pm	#209
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 I can't help you with this one unfortunately. If you are sure you are using it as intended then it could possibly be faulty from new, maybe the party who sold you it would be best placed to advise you on how to proceed. Even people who know PETs won't necessarily have any experience of using one of these as it's non-original, third party hardware. It would be interested to see some images of it, what's the storage medium? SD cards, or USB storage perhaps? Is this a PET only item, or is it C64 compatible as well like your other gadget? If it is, what happens if you try it with the C64?

15th Apr 2020, 4:14 pm	#210
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 I don't think this is a device issue. I think this is PET issue. The problems occur even when the device is not attached. The PET just freezes everytime the IEEE port is trying to be accessed - even if there is nothing attached. I expected to see the '?DEVICE NOT PRESENT' when trying to access the port without anything attached but I don't. It just freezes. I think this is a potential IC issue leading out to the IEEE port. What do you think?

15th Apr 2020, 4:38 pm	#211
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 Unfortunately this is so far outside my personal experience I can't really offer specific advice. I take it your TAPDUINO connects to the tape port and pretends to be a tape machine, so that wasn't connected to the IEEE port? Do you have any other hardware which is designed to be connected to that port?

15th Apr 2020, 4:44 pm	#212
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 Yes - the TAPUINO connects to the tape port and that continues to work. I don't have anything else. Apart from the cost (£85!) I would really like the Disk to work. I'm looking at the IEEE Schematics but not sure what I'm looking at!! LOL - I shall keep plodding away. Thanks anyway - if it wasn't for you, I wouldn't have had the machine running in thw first place! J

15th Apr 2020, 4:46 pm	#213
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 I see your friends at Tynemouth software also do something called a 'Pet Diagnostics Module' which plugs into the CPU socket and analyses various aspects of the machine, but they do not include loopback tests on the various ports, which is a pity. I really would just contact them first regarding your problems with this unit (which I also saw on the website) and they may be able to shed some light - don't forget to mention that the machine already has their other add-on Gizmo in it, the one with the offboard PROM / Memory etc. They (more than anyone ) will know what you should be expecting to see when there is nothing plugged in.

15th Apr 2020, 6:50 pm	#216
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 John, I would still suggest you contact TS to see if they recognise your symptom, they might very well say "Oh yes! That's because... all you have to do is..." If you exhaust that avenue and are still convinced you have a hardware fault with the PET and not the new hardware... This (attached) is the circuit of the IEEE interface. At the heart of it is a 6520, 'C6', presumably IC6. I don't know if your PCB has the IC numbers identified on the PCB. Also involved are A10 (7417) F1 (74LS08) and A7, A8, A9 (MC3446 * 3). If all of these ICs are now in sockets, look for the obvious things first, take each of those ICs out one at a time and make sure none of the pins got folded over by accident when they were reinserted after the sockets were replaced. If there is no obvious problem there You could try, if possible, replacing C6 (6250) A10 (7417) F1 (74LS08) The ones above are the ones you are likely to have already, or which will be easier to find. Note the 7417 probably -has- to be a 7417, not a 74LS17. If you had a full set of spare ICs available or money to burn I would suggest replacing A10 (7417) and A7, A8, A9 (All MC3446) first, since these are the devices most exposed to the outside world and with the greater likelihood of being damaged by external dark forces. Unfortunately those MC3446 ICs are pretty exotic (therefore expensive) ICs. You could order just one and try it in each of the three positions to see if it fixes your problem but - that would be a gamble as there is no guarantee that only one of the original ICs is damaged - could be more. One good thing about those is that there are three of them so you can do resistive / voltage level comparisons of each one against the other two to see if there are any obvious differences between any one of them and the other two. We'll get to that after you've tried the easier things, starting with a 6520 swap (I have the impression you have a few of those). Kyle_B - Comments acknowledged and of course other forums / fora exist, but John hasn't done too badly so far here. I don't know that we can definitely say the PET is at fault when the drive device has never been seen working. Attached Thumbnails

15th Apr 2020, 7:30 pm	#217
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 3016 I found this interesting info on, where else but Tynemouth Software's website. http://blog.tynemouthsoftware.co.uk/...rt-faults.html It mentions that the keyboard 6520 is also involved in some aspects of the IEEE port.

15th Apr 2020, 8:34 pm	#218
Kyle__B Banned Join Date: Mar 2020 Location: Nijmegen, Netherlands Posts: 142	Re: Commodore PET 3016 I was working on the theory that PETs will tell you off if you try to access a device that's not there, rather than just locking up.Without one to compare with you might have to check that behavior with an emulator. If it's as stupid as my first C64 then it could just be something as simple as a bad contact somewhere. I know I had to twist that thing at the corners to get it's datasette to work.

15th Apr 2020, 10:21 pm	#219
John Earland Hexode Join Date: May 2013 Location: Middlesbrough, North Yorkshire, UK. Posts: 442	Re: Commodore PET 3016 Thanks guys-I have 8 6250s and have tried them all with the same result. Even when nothing is attached the PET simply locks. As I’ve mentioned I was expecting to see ‘?Device not present’ or something like that and I swear I have seen the machine do this-just not now!! I can’t believe all 8 ICs are faulty but you never know. Someone else mentioned swapping the 6520s but nothing so far. I’ll check all the contacts to make sure they’re clean etc and then take Sirius’s advice and start looking at the other ICs!