bill@hp-pcd.UUCP (bill) (10/02/86)
> >When I installed a V20 in my PC, I found that DISKCOPY and FORMAT > >didn't work any more. Since it was an 8Mhz chip, I had increased > >the clock speed at the same time and perhaps that was the cause of > >the problem. > > The V20 with an 8Mhz clock is definitely the most > >bang (50% speedup) for the buck (about $25 including crystal). It > >just bugs me when basic utilities don't work. > > > I put the 8 MHz version of the V20 in my XT clone running at 8MHz and > it works fine. Diskcopy and Format work fine. In fact, I haven't found > anything that doesn't work at the 8 MHz speed. > And my performance over the 8088 was NOT negligible. This may not be a problem, but one thing you guys might want to be aware of is that, depending on the ROM BIOS you're using, there are probably software timing loops in the Int 13h diskette code (among other places) for performing certain delays (such as head settle time delay following a track seek operation, motor spin-up delay after selecting a drive, etc.) Not only does your V20 run at 8 Mhz, but the number of cycles per instruction may differ from the Intel parts (in many cases, it's fewer). By speeding things up, your BIOS pushing the limits of your disk drive's capabilities, depending on the particlar drive you're using (i.e., what may work fine on one person's machine may not work at all on another if they're using different brands of disk drives.) bill frolik hp-pcd!bill Hewlett-Packard Portable Computer Division Corvallis, Oregon