View Full Version : memory management on a HT12 based 286

September 22nd, 2014, 08:49 AM
Hello guys,

my knowledge is very rusty on this, and I wonder what my ideal config.sys would look like. The system is a Fox-II v3.4 board, 20 Mhz Harris processor, 2x1 MB parity SIMMs. The BIOS does not have the "reserve ram for EMS" (or whatever it is called) option. But the chipset is supported by the HT12MM.sys driver so I can use that. The disk controller is an AHA-1542CF SCSI card.
My goal is to maximize conventional RAM and have both XMS and EMS available, if possible, running DOS 6.22.
So far I have found that this configuration demands very restrictive settings - must disable zero wait states, fast I/O, all shadowing in BIOS.

In order to have UMBs as well, to upload a mouse driver etc., I have tried to install Last Byte Memory manager - albeit it hangs on the chipset detection process, manually adding the Last Byte driver to config.sys works. It only pops up a warning msg that this chipset is supported only by the /NOEMS option (so the proprietary EMS driver ht12mm.sys is necessary). I can also use Last Byte's UMB driver which provides 64kb UMB. The main problem is that even if I skip Last Byte completely, loading ht12mm.sys and himem.sys only, the EMS provided by ht12mm.sys acts strange. Loading wolf3d freezes with a nice screen striping effect, for example.

Maybe I should manually exclude certain range(s) of memory from ht12mm.sys - maybe it is the scsi controller or the VGA card ?

Anyone with a similar setup ? Or examples for 286 optimized config.sys files ?