From: google@holzapfel.biz   
      
   Christian Holzapfel schrieb am Donnerstag, 5. Januar 2023 um 19:30:38 UTC+1:   
   > "When bits 6 and 7 in POS Register 5 are set to 0, reading POS    
   > Registers 6 and 7 will return the channel-check-status information.    
   > This information can be status or a pointer to the status."    
   >[..]   
   > Without proper documentation on the vendor defined use of those fields, it   
   looks pretty useless...   
      
   > The MIAMI spec delivers.   
      
   Obviously the card detected a "Channel Check" condition. "Channel" seems to   
   refer to the Microchannel only, rathern than to a local bus error.   
      
   The MIAMI spec deciphers:   
      
   "With the -CHCK enable bit set in POS, -CHCK is asserted under the following   
   conditions:   
      
   - An exception condition is detected on the Local Bus during a slave read from   
   the Micro Channel. This function is only supported with the CD CHRDY Timeout   
   Disable (Bit 12, PROC_CFG) set with Timeout enabled.   
   - Local Bus parity is detected during a slave read from the Micro Channel.   
   This function is only supported with the CD CHRDY Timeout Disable (Bit 12,   
   PROC_CFG) set with Timeout enabled.   
   - A data parity error is detected on the Micro Channel during a slave write   
   from the Micro Channel.   
   - An address parity error is detected on the Micro Channel.   
   - Miami asserts CD CHRDY as a Micro Channel slave for longer than three   
   microseconds.   
   - An invalid byte enable combination is detect on the Micro Channel during an   
   access of Miami as a slave.   
   - An extra streaming data strobe is received after Miami indicates streaming   
   termination as a slave."   
      
   So only MCA related errors pop up here. Great. MCA and MIAMI are properly   
   documented, contrary to the PCB's local bus design.   
      
   When a -CHCK condition occurs, further status data can be read from POS6,   
   which reads as 0x01 in my case:   
      
   "POS 6 (Status)   
   BIT 7-5: Reserved. These bits are set to zero when a channel check condition   
   occurs.   
   BIT 4: Basic Cycle Data Parity Error. This bit, when set, indicates that a   
   data parity error occurred on the Micro Channel during a basic transfer cycle   
   to Miami   
   BIT 3: Streaming Cycle Data Parity Error. This bit, when set, indicates that a   
   data parity error occurred on the Micro Channel during a streaming data cycle   
   to Miami   
   BIT 2: Extra Streaming Data Strobe. This bit, when set, indicates that an   
   extra streaming data strobe was active after Miami as a slave indicated   
   streaming terminations.   
   BIT 1: Channel Ready Timeout. This bit, when set, indicates that Miami as a   
   slave has negated Micro Channel channel ready for more than three microseconds.   
   BIT 0: Invalid Byte Enables. This bit, when set, indicates that an invalid   
   combination of byte enables has occurred on the Micro Channel during a   
   transfer to Miami as a slave. This error condition is checked for both basic   
   transfer and streaming data    
   transfers."   
      
   Since BIT 0 is the only one set, *THIS* seems to be the specific bus error.    
      
   Sounds like SETUP transfers are running properly, but something is still wrong   
   with the MCA's BE[3:0]# lines. Probing to the rescue!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)