blog:386_shootout_pcchips_m321

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blog:386_shootout_pcchips_m321 [2021/04/17 22:24] – [Retesting] johnblog:386_shootout_pcchips_m321 [2021/04/28 14:53] (current) – [Configuration] john
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 {{:blog:386:img_1945.jpg?500|}} {{:blog:386:img_1945.jpg?500|}}
  
 +=== Checking BIOS ROM ===
  
 +Now I start looking at whether the BIOS ROM is corrupt or blank, so I fire up my trusty TL866 reader, pop in the BIOS chip and try to read it as either a standard 27C256 or 27C512, but no:
 +
 +<code>
 +$ minipro -r file.bin -p "M27512@DIP28"
 +Found TL866CS 03.2.86 (0x256)
 +Invalid Chip ID: expected 0x200D, got 0xFFFF (unknown)
 +(use '-y' to continue anyway at your own risk)
 +
 +$ minipro -r file.bin -p "M27256@DIP28"
 +Found TL866CS 03.2.86 (0x256)
 +Invalid Chip ID: expected 0x8904, got 0xFFFF (unknown)
 +(use '-y' to continue anyway at your own risk)
 +</code>
 +
 +So, I peel back the sticker on the chip, and:
 +
 +{{:blog:386:img_1946.jpg?500|}}
 +
 +As if that isn't the cheapest looking knock-off EPROM you've ever seen. And what on earth is an M321F, other than "PC-Chips **M321** **F**irmware" ???
 +
 +I can't **read** the ROM, so I don't know what state it is in, or whether this is what is now causing the system not to boot/POST. I'll have to try replacing it and writing to a **real** EEPROM using the BIOS image from another M321 board, fortunately there are several linked on the [[http://www.win3x.org/uh19/motherboard/show/3059|UH19 website]].
 +
 +**[Update 20/04/2021]** - Programmed a new W27512 eeprom with a PC-CHIPS M321 bios image, and there's still no change:
 +
 +{{:blog:386:img_1947.jpg?500|}}
 +
 +... but then I tried a MR BIOS image for the same Opti chipset as this board, and I actually get something out of it:
 +
 +{{:blog:386:img_1948.jpg?500|}}
 +
 +That says error code **03--** (BIOS checksum) ...
 +
 +I decided to reflow the solder on the BIOS socket and recheck those jumper wires I fitted at the cache sockets... just retouching each of them to make sure they were properly soldered. Then tested again:
 +
 +{{youtube>s0iVc30RQg0?large}}
 +
 +Not only that, but:
 +
 +{{:blog:386:img20210420140703.jpg?500|}} {{:blog:386:img20210420140706.jpg?500|}}
 +
 +{{:blog:386:img20210420140711.jpg?500|}} {{:blog:386:img20210420140716.jpg?500|}}
 +
 +{{:blog:386:img20210420140723.jpg?500|}}
 +
 +IT'S ALIVE, IT'S ALIVE!!! :-D
 +
 +==== Final Fixes ====
 +
 +So, it powers on, it displays stuff, and it seems that (at least) the MR BIOS ROM is working. However, there are still some issues:
 +
 +   * Keyboard doesn't work
 +   * The 'cache address line' warning and lack of detected cache is a problem
 +
 +After replacing the jumper wires around the cache sockets I get a bit more progress - the "Cache address line" failure is gone, but I have an odd-sized amount of cache showing:
 +
 +{{:blog:386:img20210420203041.jpg?500|}} 
 +
 +There's also an error code **1615** showing:
 +
 +{{:blog:386:img20210420203028.jpg?500|}}
 +
 +That should be:
 +
 +   * 15: Keyboard controller failure - okay, we knew about this one
 +   * 16: Size and test CPU cache - that makes sense, as the detected cache is wrong
 +
 +=== Keyboard Controller Replacement ===
 +
 +Amikey-2 to be fitted.
 +
 +=== Cache Socket Trace Repairs ===
 +
 +This clearly still isn't right, so we'll need to redo these repairs from scratch.
 ===== Configuration ===== ===== Configuration =====
  
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 {{:blog:m321_v2_config_1.png?500|}} {{:blog:m321_v2_config_2.png?500|}} {{:blog:m321_v2_config_1.png?500|}} {{:blog:m321_v2_config_2.png?500|}}
 +
 +=== BIOS Images ===
 +
 +AMI BIOS
 +
 +   * {{:blog:386:3pcm001-5f03a73c30e6b255497105.zip|AMI BIOS ver. 050591}}
 +   * {{:blog:386:pcchips-m321-rev2.7_2-6015e43dc9a1c900996853.zip|AMI BIOS ver. 070791}}
 +   * {{:blog:386:3pcm004-5f03a7f65d0ed318049583_2_.zip|AMI BIOS ver. 060692}}
 +
 +MR BIOS (for Opti 82C391)
 +
 +   * {{ :blog:386:opti_82c391_mr_bios_v130.zip|MR BIOS v1.30}}
 +   * {{ :blog:386:v020b32f.zip|MR BIOS v1.65}}
 +
 +//Note: To use the MR BIOS version you need either a MR BIOS or AMI branded __keyboard controller__ - alternatives, such as JetKey or Regional will __not__ work; the system will boot (and the keyboard __may__ work in DOS), but you will be unable to enter BIOS, change settings etc.//
 ===== 0 Wait State & Further BIOS Optimisation ===== ===== 0 Wait State & Further BIOS Optimisation =====
  
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 ^ Test                         ^ Config 0  ^ Config 1 ^ Config 2 ^ Config 3 ^ Config 4 ^ Config 5 ^  ^ Test                         ^ Config 0  ^ Config 1 ^ Config 2 ^ Config 3 ^ Config 4 ^ Config 5 ^ 
-|Processor Speed               | 40MHz     |          |          |          |          |          | +|Processor Speed               | 40MHz     | 40MHz    | 40MHz    | 40MHz    | 40MHz    | 40MHz    | 
-|Wait states                   | 1         |          |          |          |          |          |+|Wait states                   | 1         | 0        | 0        | 0        | 0        | 0        |
 |Norton Sysinfo CPU            |           |          |          |          |          |          | |Norton Sysinfo CPU            |           |          |          |          |          |          |
 |Norton Sysinfo HDD            |           |          |          |          |          |          | |Norton Sysinfo HDD            |           |          |          |          |          |          |
  • blog/386_shootout_pcchips_m321.1618694663.txt.gz
  • Last modified: 2021/04/17 22:24
  • by john