ATW800/2 SD slot hints

[uweseimet]

The ATW800/2 transputer card has a micro SD card slot, with the SD card working like a non-removable IDE hard drive. The MegaST version maps the slot to IDE port 1 (device 2.0), and the VME version (with the latest firmware, second batch) maps it to IDE port 4 (device 2.6). Because the ATW800/2 emulation is for a hard drive, HDDRIVER's removable media settings do not apply. Due to technical reasons (VME address space) the ports have to differ. The ATW800/2 team has confirmed that both the MegaST and the VME slot work fine with HDDRIVER 12.6. There may currently be restrictions on the card types the ATW800/2 supports. HDDRIVER treats any IDE hardware identically, only the port addresses differ based on the particular hardware interface.

Hard disk drivers, similar to TOS, search for partitions on IDE drives first, followed by SCSI and then ACSI drives. This means that yuu may end up with drive C: being on the SD card. The transfer rate is about 900 KB/s, and you would probably want drive C: to be on a faster drive. Furthermore, after removing the ATW800/2 or the SD card, after a reboot all drive IDs will be shifted and C: will be somewhere else.

With HDDRIVER you can address these issues: Simply give the SD slot a lower priority. In the screenshot this has been done for all IDE devices, but it is sufficient to only move the SD card device to a different position. With such a setup HDDRIVER scans SCSI and ACSI drives before IDE drives. The TOS boot device priority (IDE first, then SCSI, then ACSI) remains unchanged.

In a nutshell, this is what I recommend for the ATW800/2 (or similar hardware setups):

1. Do NOT install HDDRIVER on the SD card.
2. Install HDDRIVER on the drive you would install it on if there were no ATW800/2.
3. Configure HDDRIVER to scan the SD card after ACSI and SCSI devices.

The "Devices and Partitions" chapter of the HDDRIVER manual provides further information on the various drive mapping options.

An internal SD card slot like the one featured by the ATW800/2 is probably a good backup solution. With HDDRUTIL you can easily clone a drive to the SD card, for instance. An SD card that is always available and does not block an external port can also be useful as a drive for temporary data.