<p><span class="h-card" translate="no"><a href="https://ioc.exchange/@azonenberg" class="u-url mention">@<span>azonenberg</span></a></span> i&#39;m virtualizing the firmware of my Yamaha MIDI keyboard. that i bought in 2025. it comes with an ARM7TDMI</p>

<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> Side question: what cursed thing are you doing that requires interacting with an ARM7TDMI in 2025, rather than a Cortex with ADI?</p>

<p><span class="h-card" translate="no"><a href="https://bsd.network/@guenther" class="u-url mention">@<span>guenther</span></a></span> oh yeah it&#39;s much less bad</p>

<p>(there were some issues with the JTAG core as well, given that i barely even tested it before running it on the FPGA, but nothing anywhere as time-consuming and life-draining as the vile ARM document that&#39;s supposed to explain how to &quot;access memory&quot; or &quot;read core state&quot;)</p>

<p>Q: where would you think are bugs in my new implementation of a high-performance ARM JTAG debugger? in the pipelined JTAG core? in the sequencer? in the serialization logic?</p><p>A: in the ARM7TDMI manual!</p>

<p><span class="h-card" translate="no"><a href="https://ioc.exchange/@azonenberg" class="u-url mention">@<span>azonenberg</span></a></span> oh yeah STM is famous for stuff like that. ARM generally does better tho</p>

<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> Fair enough. I&#39;ve found much worse errata in other chips, I don&#39;t have the details handy but the STM32F7 or H7 crypto accelerator had backwards endianness or bit ordering or something for the documentation of the key registers</p>

<p><span class="h-card" translate="no"><a href="https://ioc.exchange/@azonenberg" class="u-url mention">@<span>azonenberg</span></a></span> like i don&#39;t believe anybody could successfully produce a debugger from the ARM7TDMI TRM</p>

<p><span class="h-card" translate="no"><a href="https://ioc.exchange/@azonenberg" class="u-url mention">@<span>azonenberg</span></a></span> that is so absurdly minor in comparison with the ARM7TDMI docs which explain several basic things like &quot;how to run instructions&quot; and &quot;how to access memory&quot; that straight up don&#39;t fucking work</p>