jeff@drexel.UUCP (Jeff White) (07/23/88)
I'm trying to find some relatively inexpensive upgrades for a Tandy 1200 (XT clone). The machines (about 4 of them) run mostly Multiplan, Lotus, and Procomm (a terminal emulator). I saw an ad for a Quadram Quadsprint 5000, at a pretty decent price ($98). It's a 2/3 expansion board that has an 8086 running at 10 MHz with a 4 kbyte cache that replaces the stock 4.77 MHz 8088. I thought this would be a great upgrade and went ahead and bought one (actually, convinced the company I'm working for to buy one). At first, it seemed pretty good. Screen scrolling (both as a terminal and under DOS) increased by about 35% (24s vs. 37s to cat (Unix) or type (DOS) a 70k file). Some DOS programs, such as chkdsk, also increased by about 35%. When working with Multiplan (2.00), the improvement averaged around 100%, quite a feat. However, I ran into a major roadblock when trying to test Lotus. It wouldn't work. The screen would come up with the 123 logo, then disappear, with the screen remaining blank nothing else happening. The instructions mentions that for some programs that don't work, there is a command which will disable the cache and should allow them to run. I tried that, and although it does work (the machine is definitely MUCH slower), it still didn't help. One thing I tried was to disable the math coprocessor in the system (an 8087-3). This seemed to solve the problem. 123, as well as all the other applications, would now work. A new problem did arise, though. The system would now freeze at random time, during the memory test, while trying to boot off the hard disk, in the middle of an application. I'm now wondering two things: 1. if you set the math coprocessor switch on a PC to be off (no coprocessor present), should the 8087 not be in socket (ie. can you leave the 8087 in the socket, activating/deactivating it just by the switch), 2. Since 123 didn't work with the 8086 and 8087 (it did work with the normal 8088, though), would a faster 8087 (8 Mhz) solve the problem? What are the symptoms of having a chip that is too slow? Although the 8086 runs at 10 MHz, it simply replaces the 8088 with no other changes, so since a 5 MHz 8087 should work with it, I would expect that it should also work with the 8086. Since the majority of machines need to run 123, obviously the upgrade must work with it. My only other option that I could think of would be to buy one of those cpu speedup kits, which conist of a faster clock crystal and cpu chip (usually an NEC V-20). I've seen one kit that can run at 6, 7, and 8 MHz and includes a V-20 for $70. I'd rather not go this route (wouldn't this also increase the speed of the bus, memory access and coprocessor chip?), since I'm probably opening myself up to many more sources of errors. I would greatly appreciate any comments or suggestions along any of the lines I've talked about. Jeff White Drexel University - ECE Dept. rutgers!bpa!drexel!jeff