Hello, Mike Hammer <mike-hammer@usa.net> wrote: > Is it possible to include the ARP support into minimal kernel? Yes, if you have the possibility to recompile the kernel (with AS86, BCC and LD86). You can change every feature by editing the file netboot/bootrom/make.config. The comments should make it clear what to edit. > In using mknbi-linux or mknbi-dos, can the bootable image have > its size >1.44MB? You can only use floppy sizes because of braindead MS-DOS. I don't have the necessary values for 2.88MB disks so they are not included. If you know exactly how a 2.88MB disk looks like (cluster size, number of clusters, number of entries in root directory etc.) you can safely add these values to the list at the beginning of netboot/mknbi-dos/openrd.c. However, the selection of different ramdisk sizes still needs some more thought. I will care for it when I have some spare time left. > Finally, Netboot seems to have a feature where i can combine .EXE > and/or .COM. I think this is a VERY NICE FEATURE. Can i combine > more than one .EXE and/or .COM? Sure, you can include as many programs as will fit into the maximum 63kB memory space (including bootrom, packet driver etc.). Well, the maximum number is something like 8 or so, but you will probably never exceed this limit. > Is there some restriction in what i can do in these programs, such as > doing screen access via BIOS INT10H console i/o service? You should be careful with using DOS functions, as the bootrom DOS simulator doesn't implement all functions available under the real DOS. Basically it supports only those functions which are commonly used by the packet drivers. Regarding BIOS interrupts, they are not changed by the bootrom itself (except for the bootstrap vectors), but additional programs like the ANSI driver change interrupts. But in general, you can safely use all BIOS interrupts. Please note when using the rudimentary memory management offered by DOS, that the maximum available space is 64kB, which includes the bootrom stack, bootrom data, packet driver code and data. Therefore, if you use DOS function 48h (allocate memory) don't expect to have more than 20 or 30 kB available - depending on the size of the packet driver. Also each DOS program gets all remaining memory space as it is done in real DOS, so you have to free all unused space in order to allow following programs to load at all. Please take a look at the source code for the ANSI driver about how to best write a program for the bootrom DOS simulator. It's basically the same as you would write a TSR program for standard DOS. Additionally, the bootrom uses interrupt number 78h to tell all loaded programs when the bootrom services are terminated. The interrupt gets called without any arguments, and can be used for example to restore the original state of redirected interrupts or to reset any hardware (like network cards) to a state which makes it usable again by the loaded operating system. 78h gets called immediately before the bootrom restores the interrupt table and jumps to the loaded operating system. > The document states combined bootrom kernel and .EXE/.COM must be > <64KB. Will the compression of kernel and .EXE/.COM still permit > me to use 32KB PROM? This depends on how well your complete bootrom is compressable. Usually, code can not be compressed as much as text can. The restriction is that the _uncompressed_ code can't be larger than 64kB because of limitations in the decompression routine. Besides, there is no real sense in using more than 64kB because the DOS simulator memory space is very limited anyway due to the netboot specification. After the bootrom has been decompressed and started, the memory layout looks like: Segment addresses 0000 - 0FFF Interrupt table, bootrom data, stack, DOS memory 1000 - 97FF Memory to load operating system into 9800 - 9FFF Bootrom code Hope, this helps. gero. -- The average man, who does not know what to do with his life, wants another one which will last forever. - Anatole France -- Gero Kuhlmann, Hannover 0511/6497525 (Voice) gero@gkminix.han.de
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