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> I'm currently writing a project in C using djgpp that runs in DOS...
> hard disk access is poor (noisy and frantic, as... Windows safe mode).
Then you should indeed try the UDMA2 driver (only for PCI/newer systems,
and UDMA probably has to be enabled in BIOS first, not supported in SCSI).
This makes reads faster and allows writes to overlap with other work. The
latter can improve the felt write speed a lot.
In addition, you should load a cache. Of course I recommend lbacache :-).
This does not support delayed writes, but on the other hand, things are
safer that way. The cache can be up to 31 MB and you can cache up to 8
harddisks, each of up to 2048 GB (!) size...
It will not make a real difference to use BUFFERS=-1, this only tells Free-
DOS "do not use free HMA space for BUFFERS - use as few as possible buffers
instead", which means slightly less overhead (because you already have lba-
cache, the BUFFERs are not really needed anyway). However, unless your CPU
is really slow, having the default number of BUFFERS (e.g. no setting in
config sys) is always okay. Do not forget to load HIMEM and use DOS=HIGH
in your config sys. Best performance is probably WITHOUT EMM386. Basically
depends on the tradeoff between "EMM386 gives you fast UMBs" and "EMM386
puts the system into protected mode and has to create a simulated real
mode environment for DOS, which causes overhead". Main use of UMBs is to
load TSRs and drivers high, to have more RAM free (with DOS=UMB line added
to enable UMB usage). EMM386 also provides several other functions, but UMB
memory is the one which has most impact on everyday apps. Of course you
HAVE to use EMM386 if you have apps which require e.g. EMS memory.
PS: Seal dead? Probably, but you could get the sources of the last version
to revive them instead of rewriting everything, I guess...
SMARTDRV /C is only needed if you enable delayed writes. If you enable them,
you should set SMARTDRV to "write buffers before returning to prompt". Then
you are safe as soon as your project returns to the prompt. You can also
invoke FDAPM FLUSH to flush a number of the more common caches like SMARTDRV.
PPS: Acrobat/DOS can do PDF 1.1-almost1.2? Indeed old. But most current
are 1.4 / 1.5? I do not think so. My up-to-1.3 acroread/Linux displays
all files so far. Probably some companies thinking "it is new so everybody
must use it to force all others to use it as well", without thinking about
whether 1.4 / 1.5 actually has features which are useful in that context.
(And try caches of 8 MB first, biggest is not automatically best...
if you use SCSI and loadhigh the cache, use TUNS. You often get a small
speed gain if you use TUNW (option to lbacache). Only if your CPU is
really fast or you want to get more effect from even small caches, add TUNA.)
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