debug.asm

A test ROM for the portal

This ROM does not need any working memory.

It tests the screen, the keyboard and the RAM.

• Displays PORTAL at startup.

• Waits around a second

• Prints all chars on all positions

• Test keyboard:

  • Wait for a key

  • Display it on all positions

  • Stops if 'ESC' is pressed

• Test memory

  • Loops writing and reading back FFH followed by 00H to all memory locations from 0800H to FFFFH (0000h-07FFH is ROM)

  • The current tested page is displayed on the left of the screen (00-FF)

  • If the test fails (FF or 00 are not written), then the address and the failure are displayed:

    1234:---*---- (RC)

    1234 is the address of the failure, followed but the failed bit pattern ('*' represents failure)

    RC is the row and column of the leftmost failed chip on the motherboard

    After displaying the error, the code spams the erroneous address with a bit pattern containing '1' for failed bits. This should enable some hardware debugging to see which memory chips are receiving '1'

    After a press of a key, the test continues at the next memory 'page', ie at the next multiple of 0100H. In the example, it would continue at 1300

  • When all the RAM has been tested, a '*' is displayed on the right of the screen and the test is restarted, so it is possible to know if at least one test was sucessful

Ram layout:

       (The labels A1-D8 are the coordinates printed on the motherboard)

                                 BACK

             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  
             |D1 |  |D2 |  |D3 |  |D4 |  |D5 |  |D6 |  |D7 |  |D8 |  
   BANK 3    |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
C000H-FFFFH  | 0 |  | 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  

             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  
             |C1 |  |C2 |  |C3 |  |C4 |  |C5 |  |C6 |  |C7 |  |C8 |  
   BANK 2    |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
8000H-BFFFH  | 0 |  | 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  

             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  
             |B1 |  |B2 |  |B3 |  |B4 |  |B5 |  |B6 |  |B7 |  |B8 |  
   BANK 1    |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
4000H-7FFFH  | 0 |  | 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  

             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  
             |A1 |  |A2 |  |A3 |  |A4 |  |A5 |  |A6 |  |A7 |  |A8 |  
   BANK 0    |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
0000H-3FFFH  | 0 |  | 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  
             +---+  +---+  +---+  +---+  +---+  +---+  +---+  +---+  

                             FRONT (KEYBOARD)

TODO

• Test sound

• Test memory unmapping

• Test 0000-07FF ram (is this really useful? hard to know. Maybe just copy code to 0800, then unmap and copy back in unmapping?)

• Test printer

• Test floppy

• Test serial (parallel?)