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From the Technical Information Library
Some PowerBook owners have had problems using MIDI because PowerBook computers have difficulty reading long data streams through their printer and modem ports. This can cause dropouts in MIDI music sequences during playback.
This problem is mostly evident when recording System Exclusive dumps, in which libraries of information, such as sound patches, are recorded to a PowerBook. Playing system exclusive information (or other data) from a PowerBook, however, is not an issue.
Overview of the ProblemThe serial communication problems on PowerBook computers affected two groups of users:
Because of design changes, the PowerBook 200 series computers do not have these MIDI problems. MIDI problems experienced by Macintosh IIvx users were addressed in version 1.0.1 of System Enabler 001. This Enabler is not required under System 7.5, since it is part of the system software.
The problems had to do with the transfer of large amounts of MIDI data TO a PowerBook. It has been resolved in the PowerBook 200 and 500 series, but is still present in PowerBook 160 and PowerBook 180.
In the PowerBook 200 and 500 series, the Power Manager disables interrupts for much shorter periods than in the PowerBook 100 series, removing the possibility of missing any interrupts from the Serial Communications Controller (SCC) chip.
Normal Recording and Playback Are PossibleWith the majority of PowerBook computers and MIDI sequencers (a software-based version of the analog multi-track tape recorder), "standard" operations are possible. Such operations include recording, playback, instrument change, volume, pitch bend, and panning.
Data such as polyphonic aftertouch and pitch bend, the usual culprits (they require large amounts of data to express) do not cause a problem. The problem does not occur when sending single patches to a PowerBook 100 series computer.
The problem occurs when one is performing system exclusive functions such as dumping banks of data or samples (samples are much larger, usually, than any bank of patches) to a PowerBook 100 series computer.
A Workaround for System Exclusive DataWhile large data dumps are at this time not possible with PowerBook 100 series computers, there is an alternative method. Instead of sending an entire bank of data, sending the information in smaller groups (one patch at a time) is possible. While this is inconvenient in comparison to sending the entire bank of info at once, it does allow system exclusive data to be transferred successfully.
It is common to have a desktop Macintosh in the home or at the office, and to use a PowerBook for live performance or for out-of-home recording work (such as at a professional studio). Patch and sample editing (which sometimes require data dumps from a MIDI device to the PowerBook) is rarely done on stage or during recording sessions. Sound editing on stage is usually impractical. As for studio work, it is much more economical to take care of pre-production tasks, such as sound editing, at home, or at a professional pre-production facility, which is almost always billed at a lower rate than recording time.
So, away from the studio, you can still easily transfer your banks, samples and sequences to your PowerBook 100 series computer via floppy, SCSI disk mode, or Personal AppleShare.
Then, once in the remote location (recording session, on stage, etc.) with your PowerBook 100 series computer, you will be able to send patches, banks, samples, and sequences to any MIDI devices with no problems.
Clearly, this is only an interim solution, but it does show that many PowerBook 100 series computer MIDI users can still get a great deal of functionality from their setups in the meantime.
References and Other TipsThe June 1992 issue of "Keyboard" magazine has a well-written article by Geoffrey Ryle on using the PowerBook 100 series computers and MIDI. The missing files problem he mentions was solved by using System 7 Tuner version 1.1.1 with his Macintosh. The functionality of System 7 Tuner version 1.1.1 was included in System 7.1, so Tuner is not necessary with System 7.1 or greater. In addition, the PowerBook 200 and 500 series computers do not have these problems.
Remember to always use System 7 Tuner version 1.1.1 with Systems 7.0 and 7.0.1 to ensure optimum performance and to avoid any missing files problems. Before adding Tuner 1.1.1, it is advisable to back up your hard disk-based data, initialize the disk using Apple HD SC Setup (use Maximum Macintosh in most cases), install or restore your System Software, drop Tuner into your System Folder, and then restore your data. This is also a risk-free way to optimize your hard disk.
Utilities That Improve CompatibilityTwo software utilities greatly enhance compatibility between PowerBook 100 series computers and MIDI programs. Until MIDI software developers provide upgrades that address the idiosyncrasies of PowerBook ports, these two programs are very useful to PowerBook 100 series computers/MIDI users:
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