CheckIt  -  Wrong/Misleading Information


Misleading information - IBM 5150 - F0000-F4000

On PC family computers, and clones, it is not possible for software to say with 100% certainty that certain hardware is not in use.
For example, if I run CheckIt 3.0 on my IBM 5150 (IBM PC), CheckIt informs me that the address space of B8000-F4000 is "<nothing>".
But CheckIt is unintentionally misleading me.
The IBM 5150 motherboard 'uses' the address space of F0000-F4000. (Technically, that is F0000-F3FFF.)
The 5150 motherboard decodes the space for read operations (even though there is nothing there).
Had I mapped a card's ROM into that space, I would have ended up with bus contention (both the card and the motherboard simultaneously driving the data bus).

CheckIt should, when it detects that it is being executed on an IBM 5150, show F0000-F4000 as '<motherboard>'.


Misleading information - Early IBM 5160 - F0000-F6000

On PC family computers, and clones, it is not possible for software to say with 100% certainty that certain hardware is not in use.
For example, if I run CheckIt 3.0 on my early IBM 5160 (IBM XT), CheckIt informs me that the address space of B8000-F6000 is "<nothing>".
But CheckIt is unintentionally misleading me.
Refer to the diagram at here.
The IBM 5160 motherboard decodes all of the address space between F0000-FFFFF (irrespective of BIOS revision).

CheckIt should, when it detects that it is being executed on an IBM 5160, show F0000-FFFFF as '<System BIOS>'.


Problem - EGA card - Errors during the Video RAM test

Regarding the IBM EGA card, and possibly other EGA cards.  You may see errors during the Video RAM test.  More information at here.

Is it that CheckIt assumes that all EGA cards have 256 KB of video RAM ?


Problem - ROM on XT-IDE/XT-CF card is not shown

I fit an XT-IDE card to my IBM 5160 (IBM XT).  The BIOS ROM on the card sits at addres D0000, and contains the 'XTIDE Universal BIOS' (XUB) of version R625.
I boot from the XT-IDE card.

PROBLEM:  If I use CheckIt 3.0's memory map functionality, that functionality does not show the XT-IDE's BIOS ROM !!

NOTE:  I see that if I use InfoSpotter software (of version 2.5) on the same computer, it too does not 'see' the BIOS ROM !!

NOTE:  The RAYXTIDE tool at here is designed to detect the BIOS ROM (loaded with XUB) on the XT-IDE card.


Misleading information - 'No Game Port'

If CheckIt displays "Joystick(s): No Game Port", you may think that you have no game port in your computer, or perhaps that the game port that you do have is faulty.
I have a fully functional game port in my IBM 5160 computer, and CheckIt (versions 2.1 and 3) report "Joystick(s): No Game Port".
It could be because I have no joysticks attached to it.


Misleading information - 'No real-time clock'

If CheckIt displays "There is no real-time clock/calendar on this machine", CheckIt is referring to the real-time clock (RTC) in an IBM AT (or AT clone).

The vast majority of third party RTC solutions for PC-class or XT-class computers do not imitate the RTC in an IBM AT.
Of note, the Amstrad 1640, an XT class computer, contains an RTC that imitates the RTC in an IBM AT.