Jonathan Software

To: Jonathan Software and Hardware From: George Cossey Date: Jul y 25, 1985 Subject: Jonathan Software Compotibility with Mocintosh. MlJcintosh compatibility lJnd the Jonathlln. A primary goal of the Jonathan software is to be compatible with the current shipped Macintosh software, end stay 6S much compet1ble as possible with future versions of the Macintosh. Since the Macintosh ROMs were used 6S a base to start this project we have started with complete compatibillty with that version of the ROM (which was somewhat incompatible with the current Macintosh). Whenever possible, the Jonathan software will be made competible with the Macintosh software. There may be cases where the software is incompatible if the appHcation writer uses system calls in an illegal or extreme 1y non-standard way. There will always be differences in the software and the hardware that will cause some incompatibility problems. 50me of the things th8t C8/J C8l1Se incompBtBDi/ity Bre the fo//oJoJ"ing: e) Jonathan specific commands bei ng added, mostl yin the color erea. b) Midi - Hac specific commends bei ng added that do not appl y to the Jonathan. c) Modules of different types and functions. Jonathan modules are more of a co- processor type 'While Midi - Mac modules are more 1i ke the Apple II end IBM PC. d) Data structure differences. Jonathan records are a superset of the Macintosh records, color fields have been added for Jonathan. Jonathan supports both types of records vitti opti mization done for the Jonathan size. e) Different CPUs result in exception frames being different. This means debuggers have to change. And in order to take advantage of the ne'w' 68020 commands assemblers & compilers ""ill have to change slightl y. f) The interrupt structure is different. Jonathan interrupt levels ere different from N8cinto~h because there are different device~ that need to interrupt. g) The Front Desk Buss on the Jonathan makes the internal interface to all mouse teyoosrd, time, end parameter memorv routines different. The access at the hsrd'w'are level is different, this "'ill not normall y effect application programs si nee they acces these functions 8t a higher level. h) Hardware address and funct10n d1fferences 'will effect programs that use the harctvlere di reetl V, such as some music programs snd some copy protection methods. 1) Handle addre$Ses are changed from Macintosh. The Macintosh used the upper address bits as data holders for handles. 5i nee the Jonathan uses 811 address bib as address bits these bits are in a different place on the Jonathan. This area is currently being addressed. I I I I Apple Computer Private and Confidential July 29, 1985 Page j) The Jonathan is a fore- runner to more edvanced operati no svstems that allw multi ple applications to be runnino at the same time. To stert rneking the transition to these operating tvstems, the Jonathan runs it's applications in the wer mode of the 68020. This means that there are some 1nstruct1ons…