I have been really looking forward to an opportunity to get some experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working. Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
Chris, I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think? Jeff On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
I guarantee the number of repaired drives will be a function of the number of available ROMS, as these and the maybe a few key caps will be the failure point for most drives. Maybe a few can be fixed with alignment and cleaning but the ROMS and other chips are the big culprits. Expect instead that you can borrow enough parts off of each set of 5 drives to make one working drive. I'd expect that there are a lot of lost case drives at VCFs inventory and Ebay at this point. b On Fri, Jan 29, 2016 at 5:49 PM, Jeffrey Brace via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Chris,
I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think?
Jeff
On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
-- <strong>@ BillDeg:</strong><br> Web: <a href="http://www.vintagecomputer.net/">vintagecomputer.net</a><br> Twitter: <a href="https://twitter.com/billdeg">@billdeg</a><br> Youtube: <a href="https://www.youtube.com/user/billdeg">@billdeg</a><br> <a href="http://www.vintagecomputer.net/readme.cfm">Unauthorized Bio</a>
Thanks guys, very helpful! See you it he morning with a lot of Commodore. :-) On Jan 29, 2016, at 6:14 PM, william degnan via vcf-midatlantic<vcf-midatlantic@lists.vintagecomputerfederation.org> wrote: I guarantee the number of repaired drives will be a function of the number of available ROMS, as these and the maybe a few key caps will be the failure point for most drives. Maybe a few can be fixed with alignment and cleaning but the ROMS and other chips are the big culprits. Expect instead that you can borrow enough parts off of each set of 5 drives to make one working drive. I'd expect that there are a lot of lost case drives at VCFs inventory and Ebay at this point. b On Fri, Jan 29, 2016 at 5:49 PM, Jeffrey Brace via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Chris,
I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think?
Jeff
On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
-- <strong>@ BillDeg:</strong><br> Web: <a href="http://www.vintagecomputer.net/">vintagecomputer.net</a><br> Twitter: <a href="https://twitter.com/billdeg">@billdeg</a><br> Youtube: <a href="https://www.youtube.com/user/billdeg">@billdeg</a><br> <a href="http://www.vintagecomputer.net/readme.cfm">Unauthorized Bio</a>
Another question related to this: If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches. On 1/29/2016 5:49 PM, Jeffrey Brace via vcf-midatlantic wrote:
Chris,
I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think?
Jeff
On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
.
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
Would I simply look on the PLA chip and find 82s100 on the top imprinted there? On Sat, Jan 30, 2016 at 6:27 PM, Jonathan Gevaryahu via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Another question related to this: If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
On 1/29/2016 5:49 PM, Jeffrey Brace via vcf-midatlantic wrote:
Chris,
I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think?
Jeff
On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some
experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
.
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
Yes, I believe so. On 1/31/2016 9:46 AM, Jeffrey Brace via vcf-midatlantic wrote:
Would I simply look on the PLA chip and find 82s100 on the top imprinted there?
On Sat, Jan 30, 2016 at 6:27 PM, Jonathan Gevaryahu via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Another question related to this: If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
On 1/29/2016 5:49 PM, Jeffrey Brace via vcf-midatlantic wrote:
Chris,
I was wondering the same thing. I would say from experience with repairing Commodore 64s at the workshop, I would bring 5-10. Some you would use for parts, but I would expect at least 5 can get fixed. But this workshop is unusual because we got a lot of people that know their stuff coming to help and lots of people working on fixing. If you want to bring 20, that is great. I wouldn't expect all to get fixed, but there is a great possibility that they can. For myself I will bring 5 working drives, and 10 non working drives. Some of them I have labeled as to the dysfunction with a post-it note. I don't have a lot of experience fixing them, I have tried cleaning some and they remained unfixed. My gut tells me that a smaller percentage can be fixed with cleaning them 10%, a bigger percentage could have chip issues like 25%, maybe 50% have component issues (capacitor, resister etc.), another 15 percent are disk head or speed issues. What does everyone else think?
Jeff
On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have been really looking forward to an opportunity to get some
experienced assistance repairing 1541 drives. I acquired several on eBay and other sources over the last couple years. Some were functional, some worked after the heads were cleaned, and some are still malfunctioning for unknown reasons. I haven't had the time to dig deeper and diagnose the problems on these. I hope that I can learn more about these this weekend and get at least some of this last category working.
Practically speaking, how many drives should I bring this weekend? Is 20 too many or is it possible to actually work on that many in a day? Are there common problems that can be addressed quickly, or is it more likely that each drive will require unique troubleshooting?
.
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
Another question related to this:
If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
Any real risks to the PLA in reading in this fashion?
Not that I am aware of. The BP-1600 programmer I use uses built-in functionality of the PLA to dump the raw original fusemap. On 1/31/2016 3:36 PM, Douglas Crawford via vcf-midatlantic wrote:
Another question related to this:
If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
Any real risks to the PLA in reading in this fashion?
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
Hi Jonathan, take a read of this. The PLA has been exhaustively investigated and read using a top max programmer. ftp://www.zimmers.net/pub/cbm/firmware/computers/c64/C64_PLA_Dissected.pdf On 31 January 2016 17:24:26 EST, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Not that I am aware of. The BP-1600 programmer I use uses built-in functionality of the PLA to dump the raw original fusemap.
On 1/31/2016 3:36 PM, Douglas Crawford via vcf-midatlantic wrote:
Another question related to this:
If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
Any real risks to the PLA in reading in this fashion?
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
-- Sent from my Android phone with K-9 Mail. Please excuse my brevity.
I'm trying to extract the actual .jed files from the PLAs for Rev2 and Rev3, which, if correct, should have the sum16s of 0x7E17 and 0x8411, respectively. As noted in the document, these come from PLAs from Signetics (82S100, PLS100) and Fairchild (93459). I'm not as interested in the MOS mask PLA, 906114-01. (either of the two versions of this, which seem to both behave the same) To the best of my knowledge, none of the readout/reverse engineering done by Jens Schoenfield was ever made public. The later decap stuff was, so we know 100% how the MOS mask 906114-01 PLA worked. BUT... the reason I'm asking about this is that I don't really trust the existing prior reverse engineering of the older Signetics and Fairchild PLAs, since the reverse engineering focus was mostly placed on the later, MOS mask 906114-01 PLA. That's why I'm asking about this. On 1/31/2016 9:29 PM, Rob Clarke wrote:
Hi Jonathan, take a read of this. The PLA has been exhaustively investigated and read using a top max programmer.
ftp://www.zimmers.net/pub/cbm/firmware/computers/c64/C64_PLA_Dissected.pdf <http://www.zimmers.net/pub/cbm/firmware/computers/c64/C64_PLA_Dissected.pdf>
On 31 January 2016 17:24:26 EST, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Not that I am aware of. The BP-1600 programmer I use uses built-in functionality of the PLA to dump the raw original fusemap.
On 1/31/2016 3:36 PM, Douglas Crawford via vcf-midatlantic wrote:
Another question related to this:
If anyone has an older 'breadbox' c64 (not c64c) with the signetics 82s100 PLA in it (only used for the first year or so before being replaced with the MOS PLA) let me know, I'd like to try to read the fusemap out with an 82s100 programmer. There exists a reverse engineered fusemap of the 82s100, but it was done "by hand" using an eprom programmer to probe all the inputs and look at outputs like a giant truth table, and based on an interview with Bil Herd a few years ago, I now know that this will not produce an accurate dump of the chip, because the engineeres at commodore played some tricks by adding extra/unnecessary gates to certain outputs to intentionally 'slow down' the edges of certain signals to prevent glitches.
Any real risks to the PLA in reading in this fashion?
-- Sent from my Android phone with K-9 Mail. Please excuse my brevity.
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
participants (8)
-
Chris -
Chris Fala
-
Douglas Crawford -
Evan Koblentz -
Jeffrey Brace -
Jonathan Gevaryahu -
Rob Clarke -
william degnan