Bulletin number: 367 Products affected: S708 Description: DOS clock stopped by B008 driver Component: Date: Thu May 23 15:47:57 BST 1991 ----- There has been some discussion recently about the B008 device driver causing some problems on certain PC's, these problems manifest themselves in two ways: the PC time is stopped, or if using DOS pipes the machine crashes and hangs. Here is an explanation of the problem and some suggestions as to how to avoid it when using the B008. HISTORY: The B008 device driver was written to increase the performance of early PC's that had faster DMA than processor I/O. Since around 1985 particularly with the advent of faster processors such as 80286 and 80386 the processor can do I/O as fast as the DMA, because the data throughput is limited only by the PC bus speed. The B008 device driver actually makes no performance improvement to the vast majority of modern machines; and could reduce performance due to the DMA setup overhead. The B008 device driver is not essential to the operation of the B008 ISERVER and can quite easily and comfortably be omitted from B008 installation as it is basically extra overhead for most machines. FIX: If you absolutely want to use the device driver (hopefully most of you have lost interest by now) and you have found the problems with the device driver highlighted above read on. The device driver normally operates from interrupt request level 3, on some machines this causes a conflict with the PC clock interrupt also at level 3 and this is the root of the problem. To use the device driver the driver has an entry in the CONFIG.SYS file which specifies driver parameters including board address AND YOU CAN MODIFY THE INTERRUPT LEVEL THE DEVICE DRIVER USES, to modify this interrupt level you use the /I option to the device driver in CONFIG.SYS, this should be in the documentation for the device driver. The recommended interrupt level for the B008 device driver is IRQ 5, this cures all problems we have seen to date. You could, however, change the IRQ to anything you want so long as it doesn't clash with MS-DOS reserved interrupts and other driver interrupts. See Bulletin 364 for details of some well known interrupts. REMEMBER to change the switch setting on the B008 to use interrupt level 5 as well!.