#145 Messenger emulation
Attached is the beginnings of emulation of the Messenger, a peripheral that allows the 48K ZX Spectrum's state to be transferred to/from the SAM Coupé. Currently, only the paging system is emulated. To test this, choose Machine->NMI after enabling Messenger emulation.
Once emulation of the serial (MIDI or MIDI-like) interface has been implemented in both Fuse in SimCoupe, it should be possible to transfer snapshots between the two emulators.
It should also be possible to transfer snapshots to/from a real SAM, although standard PC serial hardware does not support the required baud-rate (31250 baud). Provided the Messenger's handshaking signals can be accomodated, it may be possible to use a MIDI interface to communicate with the SAM.
I am not sure whether the Messenger can safely drive real MIDI devices, or another Messenger (using a MIDI coupler).
messenger.rom is available from http://homepage.ntlworld.com/wholehog/stuart/messenger.rom
Serial emulation
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The attached patch adds serial emulation. It's currently hardcoded to receive an "RX ZXROM" command. All that remains is to add code to link this with SimCoupe.
File Added: messenger-2.diff
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I've attached an new version of the patch, which should apply cleanly again. BTW, there is probably some inverted logic somewhere in the handshaking code, but it shouldn't be too hard to fix.
A disassembly of the Messenger's software may be of use: http://webshed.org/wiki/index.php/Messenger
File Added: messenger-3.diff