Parent


Ruuds Diagnostic ROM  -  Breakdown  -  Version 2019-07-23


Below, 'Checkpoint' means send the specified byte (which is in hex) to I/O ports 80h, 378h, and 278h.

I/O ports 378h and 278h are parallel (printer) ports.  If you have a parallel (printer) port at either of those ports, then the device shown at here can be used to view bytes sent to the port.

WARNING:  Note that the parallel (printer) port on an MDA (monochrome) card is typically at 3BCh, and is therefore, unusable.

On an IBM 5150 or 5160, rarely does a POST card work to monitor bytes sent to I/O port 80h.  Do not expect it to work.



For version 2019-07-23

The information in the following table was sourced from file DiagROM.asm

Step	Video enabled ?	Action	Comment
1	No	Checkpoint 00
2	No	Part 1 of CPU test.  If an error, send checkpoint 80 then halt.
3	No	Checkpoint 01
4	No	Part 2 of CPU test.  If an error, send checkpoint 80 then halt.
5	No	Checkpoint 02
6	No	See if 8-bit checksum of ROM is 00h.  If not 00h, send checkpoint 81 then halt.	Ruuds Diagnostic ROM
7	No	Checkpoint 03
8	No	Quote: 'Initialise the 8255 multi-port chip'
9	No	Quote: 'Make sure that turbo is off and disable memory parity'
10	No	Quote: 'Disable NMI interrupts'
11	No	Quote: 'Enable the expansion unit'	Extender card for IBM 5161
12	No	Quote: 'Disable the CGA and MDA video system ...'
13	Yes	Quote: 'Initialise the MDA port'
14	Yes	Quote: 'Initialise the CGA port'
15	Yes	Checkpoint 04
16	Yes	Quote: 'Clear MDA screen', then 'Set the correct mode'
17	Yes	Quote: 'Clear CGA screen', then 'Set the correct mode'
18	Yes	Checkpoint 05
19	Yes	Quote: 'Make the cursor invisible for MDA'
20	Yes	Quote: 'Make the cursor invisible for CGA'
21	Yes	Checkpoint 06
22	Yes	Quote: 'Prepare the RAM for storage'
23	Yes	Checkpoint 07
24	Yes	On-screen, display the name of the program and the version.
25	Yes	Beep the speaker.	A single beep.
26	Yes	Checkpoint 08
27	Yes	Display "Testing CPU"
28	Yes	Checkpoint 09
29	Yes	Part 1 of CPU test.  If an error, send checkpoint 82 then halt.
30	Yes	Checkpoint 09
31	Yes	Checkpoint 10
32	Yes	Part 2 of CPU test.  If an error, send checkpoint 82 then halt.
33	Yes	Checkpoint 12
34	Yes	Display "Diagnostic ROM checksum"
35	Yes	Checkpoint 14
36	Yes	See if 8-bit checksum of ROM is 00h.  If not 00h, send checkpoint 83 then halt.	ROM = Ruuds Diagnostic ROM
37	Yes	Checkpoint 18
38	Yes	Display "8253 timer channel 0"
39	Yes	Checkpoint 20
40	Yes	Quote: 'Disable the DMA controller'
41	Yes	Quote: 'Disable the speakers and enable timer 2'
42	Yes	Checkpoint 22
43	Yes	Test 8253 timer channel 0.
44	Yes	Display "8253 timer channel 1"
45	Yes	Checkpoint 26
46	Yes	Test 8253 timer channel 1.
		...
		...
		...
		...
		...
		...
		...