GILLMANN@USC-ISIB@sri-unix.UUCP (05/24/83)
From: Dick Gillmann <GILLMANN@USC-ISIB> I tried filling out the motherboard memory on my XT by buying 64K chips and putting them in. No matter how I set the switches, it didn't work. In fact, the XT acted just like they weren't there; it checked the memory out to 128K and then booted normally. Running the diagnostics gives one of those cryptic error msgs that the book says "replace the motherboard" on. So I removed the chips and everything went back to normal. Not being a hardware type, I'm pretty well stumped. The chips I put in were Mitsubishi plastic M5K4164NP-15 150ns RAMs. I'm sure I put them in the right way and they were new chips. Any help would be appreciated. Dick P.S. As near as I can determine, here are the XT switch meanings: 1 Normally OFF (ON, loop post) 2 Normally ON (reserved for co-processor) 3-4 Motherboard Memory (11=64K, 01=128K, 10=192K, 00=256K) 5-6 Displays (01=color 40, 10=color 80, 00=mono or both, 11=none) 7-8 Floppy Drives (00=4, 10=3, 01=2, 11=1) [Thanks to Shostak@SRI-CSL and JOHNSOND.IBM-SJ@Rand-Relay.] -------