Wayne Stewart writes: >Bryan Parkoff wrote: >> >> SmartPort Question >> >> I learn that Apple IIgs Reference book says that SmartPort will support >> printer, modem, network, etc near the future, but it does not exist. >> It also says that it can support up to 127 SmartPort devices. I suspect >> that it can only limit to 14 devices under ProDOS 8 because it uses slot 1 >> through 7. If it is true that ProDOS 16 supports up to 16 devices per slot. >> Please advise. >If your IIgs is running GSOS then all those devices don't have to be >mapped >to slots. While technically you can have that many devices, the disk >port is >limited by the power it can supply. I think Apple recommended a maximum >of 4 >devices. I used to use 5 when I was installing System 6 on a HD to avoid >disk swapping. After I bought a CD burner I made up an installer CD. Note that Smartport has two meanings: 1) The firmware interface used by SCSI cards, RAMdisk cards and 3.5" floppy controllers etc. 2) The hardware bus which is only used by 3.5" disk drives. The firmware interface has a limit of 127 devices and could be reached with a SCSI card with large disk(s) with many partitions as each partition shows up as a separate device. The 3.5" disk port also powers the drives and will probably run into power problems after 6 drives. Smartport supports two types of device - block and character. ProDOS 8 only supports block devices and will run out after 13 (slot 3, drive 2 is reserved for /RAM on 128KB machines). P16 probably only supports block devices. No character devices have been developed for the Smartport bus as far as I know. -- David Wilson School of IT & CS, Uni of Wollongong, Australia Bryan Parkoff wrote: > I learn that Apple IIgs Reference book says that SmartPort will support > printer, modem, network, etc near the future, but it does not exist. As David Wilson noted in another followup, the term "SmartPort" has two distinct meanings: - The protocol used to communicate via the disk port with intelligent devices like the UniDisk 3.5. - The firmware interface provided by many 3.5" drive controller cards, Apple SCSI cards, standard slot RAM cards, and the built-in SmartPort firmware of the Apple IIc and IIgs (slot 5). The protocol and the firmware interface support both block and character devices, but all the implementations I can think of have been block devices. > It also says that it can support up to 127 SmartPort devices. In theory, yes. The SmartPort protocol uses a 7-bit field in the packet header to identify the peripheral (with a value of zero being reserved), and the firmware interface uses the same convention. Specific implementations of the SmartPort firmware interface have lower limits on the actual number of devices. For example, the original Apple SCSI card only supports 7 devices, and the Apple High-speed SCSI card supports 110 (to achieve this, you would need a lot of hard drives, each with several partitions). The actual disk ports have a much lower limit, due to signal loading and power supply restrictions. I wouldn't recommend trying to connect more than four drives to a single disk port. > I suspect that it can only limit to 14 devices under ProDOS 8 because it > uses slot 1 through 7. If you use ProDOS-8 2.0.1 or later, ProDOS can make use of the SmartPort firmware interface and can remap SmartPort units into unused ProDOS unit numbers. You are limited to a maximum of 13 units (S3,D2 is reserved for /RAM), and each slot occupied by another disk controller card (or a device which look like one) will reduce the number of remappable units by two. This only affects accessing the SmartPort devices via ProDOS. Application code can use the SmartPort firmware interface directly, and bypass the limits imposed by ProDOS. > If it is true that ProDOS 16 supports up to 16 devices per slot. Nope. ProDOS-16 supports two devices per slot, like early versions of ProDOS-8. ProDOS-16 has no support for the SmartPort firmware interface (it only uses the ProDOS block driver in the card's firmware). GS/OS has a more powerful driver architecture, supporting a mixture of "loaded" drivers (supplied as files on the system disk) and "generated" drivers (which make use of the firmware supplied by the I/O card). For a card which supports the SmartPort firmware interface, GS/OS can generate a driver for each block device (and theoretically for each character device). It may be possible to reach the SmartPort limit of 127 devices given the right setup. This is somewhat of a moot point, since GS/OS requires the use of loaded drivers for most of the common SmartPort peripherals (Apple 3.5 Drive, UniDisk 3.5 and Apple SCSI). -- David Empson dempson@actrix.gen.nz