MS-DOS 1.28

According to MS-DOS 2.11 source code, MS-DOS 1.28 is an unreleased internal version of MS-DOS. At this stage of development, it is already clear that the next major release of MS-DOS is version MS-DOS 2.00 and it will differ significantly from the previous MS-DOS 1.25 release.

Change log
1.28 04/15/82 DOS retructured to use ASSUMEs and PROC labels around system call entries. Most CS relative references changed to SS              relative with an eye toward putting a portion of the DOS in               ROM. DOS source also broken into header, data and code pieces 04/15/82 GETDMA and GETVECT calls added as 24 and 32. These calls return the current values. 04/15/82 INDOS flag implemented for interrupt processing along with call to return flag location (call 29) 04/15/82 Volume ID attribute added 04/17/82 Changed ABORT return to user to a long ret from a long jump to              avoid a CS relative reference. 04/17/82 Put call to STATCHK in dispatcher to catch ^C more often 04/20/82 Added INT int_upooler into loop ^S wait 04/22/82 Dynamic disk I/O buffer allocation and call to manage them call 49. 04/23/82 Added GETDSKPTDL as call 50, similar to GETFATPT(DL), returns address of DPB 04/29/82 Mod to WRTDEV to look for ^C or ^S at console input when writting to console device via file I/O. Added a console output attribute to devices. 04/30/82 Call to en/dis able ^C check in dispatcher Call 51 04/30/82 Code to allow assignment of func 1-12 to disk files as well as devices.... pipes, redirection now possible 04/30/82 Expanded GETLIST call to 2.0 standard 05/04/82 Change to INT int_fatal_abort callout int HARDERR. DOS SS              (data segment) stashed in ES, INT int_fatal_abort routines must preserve ES. This mod so HARDERR can be ROMed.