+mytek Posted January 29, 2016 Share Posted January 29, 2016 (edited) The only non-volatile RAM is in the DS1305 RTC chip, which holds the time/date and configuration settings. The OS ROMs are in the 512KB flash ROM chip on the board, which also contains the BIOS, etc. I don't think it matters because the U1Meg looks (to the computer) as if your selected OS is a chip plugged in the OS ROM socket. Interesting. Is there ever any problem with the bios or OS being corrupted (is it somehow protected)? I ask this because unlike Bob's XL14, the U1Meg doesn't appear to have any fallback. - Michael Edited January 29, 2016 by mytekcontrols Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted January 29, 2016 Share Posted January 29, 2016 It only gets corrupted if you flash it with a bad file. It's ROM, so it's pretty safe. No battery or anything required to keep the contents safe. Quote Link to comment Share on other sites More sharing options...
+mytek Posted January 29, 2016 Share Posted January 29, 2016 It only gets corrupted if you flash it with a bad file. It's ROM, so it's pretty safe. No battery or anything required to keep the contents safe. So this may be where I'm getting confused. There is Flash ROM and SRAM on the board (if I now understand this correctly). The ROM is where the non-volatile stuff goes (Boot code, OS's, Language's, ect.). And the SRAM is strictly used as RAM expansion which is configurable to use different banking schemes (no Battery-Backup of this area). Did I get this correct? - Michael Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted January 29, 2016 Author Share Posted January 29, 2016 How do you flash it if it is the boot code is corrupted? You got no brains? Yes, flash memory is pretty solid. Little fingers typing, not so much. Bob Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted January 29, 2016 Share Posted January 29, 2016 Almost. The battery backed SRAM is used only for the clock and to hold your configuration settings data. The expanded RAM is not battery backed, nor does it need to be. Quote Link to comment Share on other sites More sharing options...
+mytek Posted January 29, 2016 Share Posted January 29, 2016 (edited) How do you flash it if it is the boot code is corrupted? You got no brains? Yes, flash memory is pretty solid. Little fingers typing, not so much. Bob The 39SF040 512x8 FLASH ROM is the socketed chip on the board. So I suppose if worse came to worse it could be removed and put in a programmer to be re-flashed. - Michael I just un-packaged my U1Meg and took a close look at it. Edited January 29, 2016 by mytekcontrols 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted January 29, 2016 Share Posted January 29, 2016 I know I'm getting a bit of topic, and I apologize for that. But since we are talking about the U1Meg, I have a question relating to the OS and MMU connections. My board came with 2 IDC (0.1" dual row connector) ribbon cables (same connector at both ends). To facilitate connection to the DIP sockets, there are two daughter boards that the ribbon cables plug into which accept the ribbon connectors on one side and have a DIP header on the back side (20 pin and 28 pin). When I connected everything up, I did a continuity check from pin 1 on the DIP socket to pin 1 as marked on the U1Meg board. No beep. But when I touched the opposite pin 2, I did get a beep (continuity confirmed). This was the same with both cables, and I double-checked that the striped side of the ribbon lined up with pin 1 on both the socket daughter board and on the U1meg. So my question is... Is the number mapping not the same on the U1Meg board vs the socket daughter board? - Michael Quote Link to comment Share on other sites More sharing options...
+mytek Posted January 30, 2016 Share Posted January 30, 2016 (edited) The answer to that last post is: No it's not mapped the same. It would have been kinda hard to do so since the IDC connector pin numbering scheme has all even numbers on one row and all odds on the other row. This is not the same as how a DIP socket is numbered. I guess what really threw me off was that I was expecting both pin 1's to be connected, and they weren't. Now back to the original topic: The XL14 - Michael Edited January 30, 2016 by mytekcontrols 1 Quote Link to comment Share on other sites More sharing options...
oky2000 Posted January 31, 2016 Share Posted January 31, 2016 .....I want one that will play Rescue on Fractalus as well as the C64 SuperCPU fixed version (look it up on youtube), now I have a choice between slow but beautiful or silky smooth AND fast but muddy looking.....sometimes life is PURE HELL!!!! Quote Link to comment Share on other sites More sharing options...
+mytek Posted January 31, 2016 Share Posted January 31, 2016 .....I want one that will play Rescue on Fractalus as well as the C64 SuperCPU fixed version (look it up on youtube), now I have a choice between slow but beautiful or silky smooth AND fast but muddy looking.....sometimes life is PURE HELL!!!! Yes what is one to do? - Michael Quote Link to comment Share on other sites More sharing options...
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