
===========================
TEST 3  -  DMA INIT
===========================

Step 1. Performs CPU test - halt on fail
Step 2. Verifies that 8 bit checksum of ROM is 00 - halt on fail
Step 3. Timer 1 - verify that it functions okay
Step 4. Timer 1 - set it up to refresh memory
Step 5. 8237 DMA initialisation and test - halt on fail
Step 6. Displays "03" on the POST card then halts

Note: On a good 64-256k board, you may see "AA" then "75" temporarily before the "03"



Based on the 27OCT82 version of the BIOS chip, U33.
The following code was substitued at offset 014B.
U33 appears at FE000 and so for example, offset 0123 will be address FE123 in the machine.

OFFSET CODE         
------------------------------------------------
014B   B0 04   MOV AL,4      ; disable DMA controller
014D   E6 08   OUT 8,AL      ;    "     "      "
015F   BO 03   MOV AL,3
0161   E6 80   OUT 80H,AL    ; send 03 to POST card
0163   F4      HLT           ; halt

Note: It was found necessary to disable the DMA controller to get the POST card to display a code.

