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Support ICD (Atari ACSI) command semantics (#640)

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* Initial ICD support

* Comment update

* Comment update

* Comment update

* Update README.md
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Uwe Seimet 2022-02-05 02:45:10 +01:00 committed by GitHub
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README.md
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@ -1,5 +1,5 @@
# What is RaSCSI?
RaSCSI is a virtual SCSI device emulator that runs on a Raspberry Pi. It runs in userspace, and can emulate several SCSI devices at one time. There is a control interface to attach / detach drives during runtime, as well as insert and eject removable media. This project is aimed at users of vintage Macintosh computers and more (see [compatibility list](https://github.com/akuker/RASCSI/wiki/Compatibility)) from the 1980's and 1990's.
RaSCSI is a virtual SCSI device emulator that runs on a Raspberry Pi. It runs in userspace, and can emulate several SCSI devices at one time. There is a control interface to attach / detach drives during runtime, as well as insert and eject removable media. This project is aimed at users of vintage Macintosh and Atari computers and more (see [compatibility list](https://github.com/akuker/RASCSI/wiki/Compatibility)) from the 1980's and 1990's.
Please check out the full story with much more detail on the [wiki](https://github.com/akuker/RASCSI/wiki)!

32
src/raspberrypi/gpiobus.cpp
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@ -861,6 +861,38 @@ int GPIOBUS::CommandHandShake(BYTE *buf)
goto irq_enable_exit;
}
// The ICD AdSCSI ST, AdSCSI Plus ST and AdSCSI Micro ST host adapters allow SCSI devices to be connected
// to the ACSI bus of Atari ST/TT computers and some clones. ICD-aware drivers prepend a $1F byte in front
// of the CDB (effectively resulting in a custom SCSI command) in order to get access to the full SCSI
// command set. Native ACSI is limited to the low SCSI command classes with command bytes < $20.
// Most other host adapters (e.g. LINK96/97 and the one by Inventronik) and also several devices (e.g.
// UltraSatan or GigaFile) that can directly be connected to the Atari's ACSI port also support ICD
// semantics. I fact, these semantics have become a standard in the Atari world.
// RaSCSI becomes ICD compatible by ignoring the prepended $1F byte before processing the CDB.
if (*buf == 0x1F) {
SetSignal(PIN_REQ, ON);
ret = WaitSignal(PIN_ACK, TRUE);
SysTimer::SleepNsec(SCSI_DELAY_BUS_SETTLE_DELAY_NS);
// Get the actual SCSI command
*buf = GetDAT();
SetSignal(PIN_REQ, OFF);
if (!ret) {
goto irq_enable_exit;
}
WaitSignal(PIN_ACK, FALSE);
if (!ret) {
goto irq_enable_exit;
}
}
count = GetCommandByteCount(*buf);
// Increment buffer pointer