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Post AydzzZyAfk9orETyiG by [email protected] |
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More posts by [email protected] |
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Post #AyYEoozmnYjKdeo51U by [email protected] |
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i've been tinkering with this board which emulates an IBM 729 tape unit. (s… |
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Post #AyYEop8IHvXH42msHg by [email protected] |
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the original design was built around 2005-2008 or so when the team was trying t… |
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Post #AyYEopFjqFUTR8Got6 by [email protected] |
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the original emulator uses two ribbon cables that go from the emulator to one o… |
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Post #AyYEopNBOZRfoDklUW by [email protected] |
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in my new design, i've incorporated everything inside that 19" rack, i… |
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Post #AyYEopUyvZgSCPOzeC by [email protected] |
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it's been a slow bringup process since i want to be very careful about conn… |
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Post #AyYEopc4VDM4YOiehM by [email protected] |
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the 729 is a little unusual in that, during a read operation, it just amplifies… |
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Post #AyYEopc4VDM4YOiehN by [email protected] |
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the waffle connector is supposed to take the place of the bus terminator that n… |
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Post #AyYEopjs2DaqwaMsr2 by [email protected] |
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oh yeah IBM logic levels are weird. the tape units use "P" and "… |
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Post #AyYEoprJaXY3JfqpSS by [email protected] |
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the read bus circuit is a bit more complex. the big orange block on the right-h… |
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Post #AyYEopxhCoeVdSpvP6 by [email protected] |
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appears the transformer card has a problem. can you see it? |
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Post #AyYEoq3MrjBnv3USFE by [email protected] |
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@tubetime is that pad pushed off? hard to tell from the image (please always po… |
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Post #AyYpp1JkgLDh9u6U0O by [email protected] |
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@tubetime The solder is not shiny. And one of the traces looks like rusted. But… |
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Post #Aydvk4tLXM8eJLZwY4 by [email protected] |
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got the full complement of cards to implement the read channel for 1 bit. it se… |
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Post #Aydvk5194MNQhXEAhk by [email protected] |
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the read channel in the 1401 looks like this. a YBY card buffers the analog pul… |
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Post #Aydvk57sfJlT2QNYCe by [email protected] |
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here are the waveforms. channel 1 is the raw output of the 729 emulator. channe… |
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Post #Aydvk5FKDdifPVrUo4 by [email protected] |
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you can see that the low threshold output is sensitive to lower amplitude input… |
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Post #Aydvk5LLrEXXiCgJCS by [email protected] |
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but during a normal read operation, the 1401 only looks at the low threshold da… |
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Post #Aydvk5R1W94pznKq2a by [email protected] |
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my board also has a built-in oscilloscope to make it easy to check bus waveform… |
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Post #Aydvk5XP8QBIJaJvzE by [email protected] |
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the idea is to use DMA to fill up a buffer with ADC samples at the fastest i ca… |
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Post #Aydvk5dmkhHkdNJ1vs by [email protected] |
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as usual the code doesn't work the first time. looks like a DMA transfer er… |
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Post #Aydvk5kAMyOCxAI7sW by [email protected] |
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and yet the ADC results appear to be OK, so the ADC itself works fine. hmmm |
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Post #Aydvk5qC0ZD5Fr6wGu by [email protected] |
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docs say a transfer error is caused by a bus error. so perhaps there is a probl… |
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Post #Aydvk5wDeA1xYXvkfI by [email protected] |
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@tubetime had to look up DTCM. That’s special memory that is higher clocked? |
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Post #Aydvk66r0cXO5WuFF2 by [email protected] |
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thought so! according to the bus matrix, DMA1 can't access the DTCM (data t… |
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Post #AydzVOZKUlZSoNTDjU by [email protected] |
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@tubetime I see what looks like a detached solder pad and a couple of damaged t… |
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Post #AydzdnNe88nK510kM4 by [email protected] |
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@tubetime that’s right, calcium. Here’s the model of a calcium molecule. Do… |
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Post #Aydzexe7RqkiCxGv1k by [email protected] |
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@tubetime Curious... what are the unpopulated J1 and J2 headers for? |
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Post #Aydzf1ecXvWwdfXNMe by [email protected] |
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@dragonarchitect yes middle pad is detached. |
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Post #AydzlZOi0C2Z1tDOvg by [email protected] |
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@tubetime The round pad on the left also looks like it might have a broken trac… |
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Post #Aydzo17btYg9asNtNg by [email protected] |
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@tubetime wow, the period design on the tape decks really is something else! gi… |
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Post #AydzryTNgYfUXLSEpU by [email protected] |
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@RueNahcMohr no stereo images, those are too hard to alt text |
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Post #AydzxwfvHYY2hOATkO by [email protected] |
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@tubetime - Does the emulator have memory or a solid state drive to store all o… |
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Post #AydzxwnMpsVF4TeQLo by [email protected] |
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@ZoeTheRobot it'll get buffered one record at a time in the local MCU but t… |
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Post #AydzySXWoIqZWcUE6a by [email protected] |
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@ducksauz these will get populated and connect to the 2 ribbon cables that go t… |
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Post #AydzzZyAfk9orETyiG by [email protected] |
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@tubetime I assume this shaping circuitry sits on the left side of the board? A… |
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Post #Aye00ueBHMU5HGlgZs by [email protected] |
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@tubetime wait wtf it's not symmetrical |
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Post #Aye05iiP4Kvbif2GX2 by [email protected] |
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@hennichodernich yup! |
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Post #Aye0AT72VTKAmCp5kW by [email protected] |
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@tubetime These Tapes were high-tech at the time. With vaccum to pull the tape.… |
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Post #Aye0CkTEwNrXBtIJQe by [email protected] |
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@tubetime If you want to write to DTCM use the MDMA instead |
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Post #Aye0F4qGAhq2wzAjIm by [email protected] |
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@tubetime {Rue drops BGA onto your connector} |
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Post #Aye0GEzztSPOk2HWTY by [email protected] |
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@RueNahcMohr CPU socket |
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Post #Aye0JpycrooYIMM4nY by [email protected] |
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@RueNahcMohr @tubetime looks like a cut trace going to it? And/or poasible the … |
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Post #AyeDHK0W3a7by6MzwG by [email protected] |
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@tubetime you don't even really need the linker script if you know nobody i… |
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Post #AyeDSqCahK1j0JVit6 by [email protected] |
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ok that took a lot longer than i thought mostly because stm32-cmake is kinda a… |
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Post #AyeDSriX43AfhfSkJU by [email protected] |
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like @azonenberg suggested i could have used the MDMA :pensive_party_blob: on t… |
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Post #Ayer6pp7QAHtcqaqAa by [email protected] |
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@root42 @tubetime not higher but on a separate bus coupled directly to the cpu … |
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Post #Azj2E49MTafi0w4Euu by [email protected] |
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the code is very hacky right now but the oscilloscope mode works! this is the r… |
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Post #Azj2E4GS3ELKMvNty4 by [email protected] |
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hmm it's even good enough to examine the overshoot on the 729 bus drivers |
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Post #Azj2FbfZKxskGKrno8 by [email protected] |
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@tubetime always been amazed by the DMA capabilities of the STM32. I was able t… |
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Post #Azj2Ib0uERsD65GxFY by [email protected] |
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@tubetime Just lovely work!Have to chuckle at the *high speeds* here, each 5ms … |
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Post #Azj2IsGm4hfScDpMqO by [email protected] |
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@azonenberg @tubetime |
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Post #Azj2IsODd1cezJJJRo by [email protected] |
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@macegr @azonenberg hahah! |
