vsystem: hook up rs232 to f1gp, gstriker and tail2nos. #14045
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Test-Footage. https://youtu.be/jnX99usnKg0?t=40 big thanks to Kale and startaq for their input. |
src/mame/vsystem/f1gp.cpp
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| @@ -120,6 +124,8 @@ class f1gp_state : public driver_device | |||
| required_device<palette_device> m_palette; | |||
| optional_device<generic_latch_8_device> m_soundlatch; // not f1gpbl | |||
| required_device<acia6850_device> m_acia; | |||
| optional_device<rs232_port_device> m_rs232a; | |||
| optional_device<rs232_port_device> m_rs232b; | |||
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Does the bootleg also have the same linking hardware? Then those could be changed to required_device and hooked up there too.
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good call. it appears to have similar hardware.
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the bootleg software probably still supports it, although I'd be quite surprised if they actually have the connectors on the board (but that could vary from bootleg to bootleg)
src/mame/vsystem/f1gp.cpp
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| // dual DE-9 ports | ||
| // COM-IN (inner) and COM-OUT (outer) according to manual | ||
| rs232_port_device &rs232a(RS232_PORT(config, "rs232a", default_rs232_devices, "loopback")); | ||
| rs232a.rxd_handler().set("rs232b", FUNC(rs232_port_device::write_txd)); |
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Instead of rs232a and rs232b a better name might be com_in and com_out then? I assume rs232a would be the COM-OUT, why does it have an rxd handler? Isn't it only used to transmit data?
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that rxd handler is for the default "loopback" slot option to work properly.
EDIT now that I think of it, the loopback is no longer needed, right?
- renamed rs232a and rs232b in dual port configuration to "com_out" and "com_in". - hooked up the 6850 in the f1gp bootleg. - rs232 devices in f1gp and tail2nos are no longer optional. - removed (default) loopback slot option.
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The one small problem is that the actual baud rate is likely not 19200 or 38400 or any other standard rate. Someone with a PCB of one of these games needs to measure what frequency is present on MC6850 pins 3 & 4. |
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someone on discord offered to trace those on a "super formula" board. has no ways of measuring them though. |
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according to the person on discord, pin 3 and 4 are connected together and fed by pin 6 of a LS393. based on that and the datasheet of a LS393 the divider should be 16. given some tolerances, I'd setup the rs232 defaults with 76800 baud. |
tail2nos and f1gp use an MC6850 with dual DE9 ports to link up to 6 units in a ring.
gstriker has only one DE9 port to link 2 units.
the exact clock of the MC6850 is unknown.
6 players fails at 19200 baud, but works with 38400 baud (and up).