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 OVERXMS - Load Overlays in XMS for TP 5.0+   Wilbert van Leijen 05.05.1992

Модуль для размещения оверлеев в XMS памяти.
This package is for users of Turbo Pascal, version 5.0 or later. These files are all you need to add XMS support to overlaying.



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READ.ME -- Loading Overlays in XMS Files ----- Apart from this notice, the following files should be present in this archive: OVERXMS.ASM Source code of XMS overlay support. OVERXMS.OBJ Object code of XMS overlay support. OVERXMS.PAS Declares OvrInitXMS. Purpose ------- This package is for users of Turbo Pascal, version 5.0 or later. These three files are all you need to add XMS support to overlaying. If you think you can use it, then I probably don't have to explain what the benefits are of using XMS memory over EMS memory - or emulations thereof. But I will anyway: - XMS is found on more machines than EMS. - All XMS is addressable as one physical unit, not in chunks of 16 kB like EMS. - XMS is faster. How much faster, depends on the kind of system. It probably doesn't matter much on 386/486 systems, but the speedup is noticable on a 286 with emulated EMS. Or if you have a typical 1 MB 286 clone, configured as 640+384, without either board EMS or emulated EMS (served by e.g. Quarterdeck's QRAM memory manager), then thanks to OVERXMS you'll have fast loading overlays at last. ... and last but not least: - OVERXMS is compact. It adds a mere 425 bytes of code to your .EXE file. Using OVERXMS ------------- Usage is straightforward. Just change the "uses" clause, so that it includes OVERXMS. Next, spot the line wherein you initialise the overlay manager. Add two lines, so that it will run something like: OverInit(YourApplication); OvrInitXMS; If OvrResult <> OvrOk Then OvrInitEMS; That's all. First, we check whether we can load the overlay into XMS; if we don't succeed, we resort to EMS allocation and suffer a slight loss of performance; if no EMS is available, though luck -- continue with overlays on disk. Status codes ------------ Possible return codes from OverInitXMS are: OvrOk (0) ... success OvrIOError (-4) ... something went wrong whilst reading the