Nп/п : 34 из 34
От : Eugene Subbotin 2:5075/35 20 сен 26 16:45:20
К : Grzegorz Worona 20 сен 26 16:48:02
Тема : Re: Courier emulation - the 80186 half
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@MSGID: 2:5075/35@fidonet 6aafe3cb
@REPLY: 7218.ru.modem@2:484/101 597a0b2b
@CHRS: CP437 2
@TZUTC: 0300
@TID: hpt/nbsd 1.9 2024-03-02
Hello Grzegorz!
Sunday September 20 2026 14:39, you wrote to me:
GW> Thank you for the reply. On almost everything we agree, and on the
GW> missing piece you named - the AIC and a model of the line - I think
GW> you are exactly right. But on one point I have to disagree, gently,
GW> and I would rather show you than just assert it.
GW> That the firmware holds only the 80186 side, with calls into the
GW> datapump but not the datapump itself, is the common belief - I held
GW> it too, until I disassembled the image. It is not so.
GW> The TMS320C52 has no non-volatile memory of its own. So its program
GW> cannot live in the DSP - it has to be somewhere, and the only place
GW> left is the flash. At power-up the 80186 streams the DSP image into
GW> the DSP program memory over the host-download port, and only then does
GW> the DSP start executing. This is the ordinary C5x bootstrap; the part
GW> simply cannot come up any other way.
Oh, now that is very interesting information. If the datapump code
exists in the firmware file, things will be much easier. I hope the
emulator`s author adds it to the project. I took a quick look at the code,
and there is already some groundwork laid for handling the DSP and
datapump. Overall, I like this USR Courier reverse-engineering project.
Eugene
... It`s full of stars!
--- GoldED+/BSD 2.0.0-b20260912 (NetBSD 11.0 Intel Xeon Icelake)
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