============================================= Amiga Parallel Port ZIP Drive Adaptor ============================================= v0.5 By Bruce Abbott (bhabbott@inhb.co.nz) Introduction ------------ The Iomega ZIP 100 drive is available with a choice of either a SCSI or a parallel port interface. Unfortunately the parallel version could not be used on an Amiga - until now! This project consists of both hardware and software - a small interface that connects to the Amiga's parallel and joystick ports, and a driver file which causes the ZIP drive to operate like a standard SCSI device. History ------- v0.0 - Initial release v0.1 - Corrected pin numbers on circuit diagram v0.2 - Fixed bug in timedelay (was not freeing memory). - Now obtaining joystick port legally, via gameport.device v0.3 - Split large data transfers into 128K blocks, rather than using MaxTransfer setting in mountlist. This circumvents a bug in CrossDOSFileSystem v39.4 (which corrupts files if _any_ Maxtransfer setting is used). v0.4 - Using TEST_UNIT_READY and READ_SENSE commands to determine if r/w error is actually 'no disk in drive'. - Increased timeouts up to 3 seconds (greater than maximum drive spinup time). - Reduced Timer overhead. Now only opening timer.device once, instead of on every time delay. Allocated ioreqs static instead of using AllocMem. v0.5 - Using 10 byte SCSI read/write commands. Can now do large transfers (>128K) directly. - Included circuit diagram with no 7407 buffer chip, as buffering is not required in most cases. - Included 'ZIPC' mountlist for peecee formatted disks. Building the Interface ---------------------- You need:- 1 D25 plug 1 D25 socket 1 D9 plug 1 7407 TTL buffer chip (only if buffering is required) 1 capacitor 1uF (only if buffering is required) some wire to connect the bits together A neat job can be done by starting with an RS232 jumper box, and a cable robbed off an old joystick. Wire the circuit according to the included diagram. Please check your connections carefully, as incorrect wiring could fry your Amiga's CIA chips! NOTE: You may not need to install the 7407 and capacitor. as most ZIP drives can be driven directly from the Amiga. Installation ------------ Plug the hardware interface into your Amiga's parallel port and joystick (Game2) port, and attach your ZIP drive to its output. Copy the driver 'ppazip.device' to your DEVS: drawer. Also, copy the mountlists 'ZIP0' and 'ZIPC' to anywhere you want (eg. Storage/ DOSdrivers). If you have a Modem plugged in at the same time, make sure that its Ring Indicator line (pin 22) is disconnected. Otherwise an incoming call might interfere with the ZIP drive (this can also cause trouble with printers, and is due to RI being connected to SEL in the Amiga). Performance ----------- It's not fast. However, the results are quite good for a parallel port interface - much faster than Parnet for example. Whilst the driver is necessarily CPU intensive, it does not disable multitasking or block interrupts. No errors occured when downloading files using ZModem protocol at 28,800baud, directly to the ZIP drive. Here's a DiskSpeed 3.1 report, from my A1200 with 68030/40MHz. Device: ZIP0: Test Intensity: Low Performance Stress: None 13 Files/s Create 19 Files/s Open/Close 48 Files/s Scan 51 Files/s Delete 925 Seek/Read Buffer Size 512 4096 32768 262144 ----------- --------- --------- --------- --------- Bytes/s Create 23831 89478 100312 108590 Bytes/s Write 24559 93433 105475 113599 Bytes/s Read 24646 93426 105323 113615 Limitations ----------- Currently the device does not poll for disk changes. You must run 'diskchange' to log on a new disk. This may be fixed once I find out how to report disk changes to the OS :-( SCSI Direct commands are not supported, which may prevent programs such as 'ZIPTools' from functioning. Therefore you probably won't be able to remove write-protect passwords etc. The ZIP's printer passthrough doesn't work. This is due to the control lines being routed to different pins by the adapter. Of course you can't print while the driver is active anyway (since the ZIP driver needs exclusive use of the parallel port). Because the interface uses your joystick port, some games may be unplayable (works OK with ADoom though, so who cares :-). Bugs ---- Due to the limited diskchange detection, if you remove the disk and then try to access it you will get a 'You MUST insert volume xxx' requester. Just put the disk back in and hit 'retry' :-) Occasionally the ZIP drive will corrupt read data. Usually this is noticed by the driver, which will then retry and get good data. However, there is a small chance of corrupted data slipping through without the drive reporting any errors. Therefore I recommend storing critical files in archived form (eg. lha), and not running applications directly from the ZIP drive. Legal ----- This project is Public Domain. Do with it as you wish, but don't blame me if you damage your Amiga, ZIP drive or anything else! It might trash files on your ZIP disks, so don't use it for anything important unless you make backups first. Bruce Abbott (bhabbott@inhb.co.nz)