Softguard Systems Inc, Santa Clara, describes its new 80386 DOS Developer’s Tool Kit and VM Run (CI No 631) as not unlike IBM’s MVS/XA on the IBM 3090s. It points out that MVS/XA allows for the migration from 24-bit – 16Mb address space – to 31-bit – 2Gb – applications while preserving established interfaces for the developer. VM Run, it says, is conceptually similar in that it allows developers to write large applications that can interface with a 20-bit operating system, namely MS-DOS). The Tool Kit enables developers to write programs larger than 640Kb that run in the protected mode of the 80386 under PC-DOS 2.x or 3.x – applications can be right up to the limit of 1Gb if you’ve got enough memory on your 80386. Applications developed with the Tool Kit run under an existing PC-DOS and users do not have to wait for a new version of PC-DOS or learn Unix. The Tool Kit uses the VM Run program to load the 80386 application into protected mode. When the application requests a DOS or BIOS service, VM Run automatically passes the request to PC-DOS in the Virtual 86 mode, and after the request has been been serviced, VM Run returns control to the 80386 program. VM Run also supports writing directly to video RAM, and the company says that in general, any technique that the PC-DOS developer has used in his current programs will continue to work. VM Run uses a flat memory model similar to that of the Motorola 68000, DEC VAX and IBM 370 and no segment registers are used. The segment origins for code data and stack are all equal and programs can increment through multi-megabyte data structures by simply updating a general register so that developers can think of their applications as giant COM files. The Tool Kit includes VM Run, an 80386 assembly language debugger, a choice of High C or Professional Pascal compiler from MetaWare, and Phar Lap Software’s 80386 assembler and linker. The debugger supports the hardware debug registers of the 80386 and lets the user set breakpoints either on instruction execution or data access to specific memory locations. All applications written with the Tool Kit will run under Softguard’s VM 386 control program, which is due to be available in the second quarter. VM 386 will multitask existing 8086 and 8088 applications with 80386 protected mode applications that were developed with the Tool Kit so that users can run things like their current versions of Lotus 1-2-3 and dBase III alongside 80386 applications. The Tool Kit sells for $2,000 and developers who buy it also get a licence to bundle one copy of the VM Run modules with each 80386 application they ship. Assembly language programmers can also buy the Tool Kit without a compiler; there are volume discounts.
