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| Advice on determining a logic analyzer for use with 1980s synthesizers. TLA715? |
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| TomKatt:
--- Quote from: tggzzz on June 15, 2024, 06:51:01 pm ---The low end modem LAs have very restricted functionality w.r.t. filtering and triggering. Decent modern LAs are fine, as are old LAs from that period, e.g. >HP163x. --- End quote --- That would seem to rule out the LA features included in entry level oscilloscopes…. You’re definitely going to need a good dedicated device for this kind of analysis. |
| artag:
--- Quote from: TomKatt on June 15, 2024, 07:25:09 pm --- --- Quote from: tggzzz on June 15, 2024, 06:51:01 pm ---The low end modem LAs have very restricted functionality w.r.t. filtering and triggering. Decent modern LAs are fine, as are old LAs from that period, e.g. >HP163x. --- End quote --- That would seem to rule out the LA features included in entry level oscilloscopes…. You’re definitely going to need a good dedicated device for this kind of analysis. --- End quote --- That's right. I've only ever seen timing analysers included in oscilloscopes. This is not really an LA, it's a bunch of very low resolution oscilloscope channels for use in systems where 2 or 4 analog channels aren't very useful. That's why they're called 'mixed signal oscilloscopes' rather than 'mixed domain analysers'. The better ones offer SPI/RS232/I2C protocol analysis via oversampling which helps make sense of serial data but to usefully display an instruction stream you want clocked capture and possibly demultiplexing clocks. |
| artag:
--- Quote from: tggzzz on June 15, 2024, 04:58:11 pm --- Memory efficiency is relatively unimportant, especially now memory is so cheap. What is important is being able to ignore rubbish, so you can concentrate on what is important. That's why state-based arm/trigger/filter is so important: it saves your time. If you don't capture the crap, there's nothing to ignore. Alternatively: good luck finding the "wrong" bit in 10MS of 32 bit captures. --- End quote --- Sure, for modern analysers, but I was referring to getting remaining value out of old machines like a 1630 or 16510 card. If operating in state mode you're only using one word per instruction, rather than oversampling, and per my description elsewhere you can get a lot of useful repair information out of the first few K of execution cycles (or a few K around the right trigger point). IIRC even the 1630 had a couple of levels of trigger, not just an address comparator. Totally agree about using the trigger to reduce the amount of unwanted data though. |
| tggzzz:
--- Quote from: artag on June 15, 2024, 08:08:24 pm --- --- Quote from: tggzzz on June 15, 2024, 04:58:11 pm --- Memory efficiency is relatively unimportant, especially now memory is so cheap. What is important is being able to ignore rubbish, so you can concentrate on what is important. That's why state-based arm/trigger/filter is so important: it saves your time. If you don't capture the crap, there's nothing to ignore. Alternatively: good luck finding the "wrong" bit in 10MS of 32 bit captures. --- End quote --- Sure, for modern analysers, but I was referring to getting remaining value out of old machines like a 1630 or 16510 card. If operating in state mode you're only using one word per instruction, rather than oversampling, and per my description elsewhere you can get a lot of useful repair information out of the first few K of execution cycles (or a few K around the right trigger point). IIRC even the 1630 had a couple of levels of trigger, not just an address comparator. Totally agree about using the trigger to reduce the amount of unwanted data though. --- End quote --- We are in violent agreement :) With skill and imagination and the right task, old working LAs can still be useful. |
| tggzzz:
--- Quote from: artag on June 15, 2024, 07:59:07 pm --- --- Quote from: TomKatt on June 15, 2024, 07:25:09 pm --- --- Quote from: tggzzz on June 15, 2024, 06:51:01 pm ---The low end modem LAs have very restricted functionality w.r.t. filtering and triggering. Decent modern LAs are fine, as are old LAs from that period, e.g. >HP163x. --- End quote --- That would seem to rule out the LA features included in entry level oscilloscopes…. You’re definitely going to need a good dedicated device for this kind of analysis. --- End quote --- That's right. I've only ever seen timing analysers included in oscilloscopes. This is not really an LA, it's a bunch of very low resolution oscilloscope channels for use in systems where 2 or 4 analog channels aren't very useful. That's why they're called 'mixed signal oscilloscopes' rather than 'mixed domain analysers'. The better ones offer SPI/RS232/I2C protocol analysis via oversampling which helps make sense of serial data but to usefully display an instruction stream you want clocked capture and possibly demultiplexing clocks. --- End quote --- For decoding SPI/UART/I2C protocols, if I didn't already own something suitable then I would evaluate a BusPirate5 for ~$45. BusPirate3 was becoming long-in-the-tooth, BuisPirate4 was a misfire, but BusPirate5 is better. |
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