Posted on July 17, 2007 at 09:31I am working on the migration of an AAEON SBC-456E board to an AAEON HSB-440I board.
On the first, obsolete, board, there is a SM-712 display chipset.
I have to modify a DOS application to make it work on the new CPU board equipped with an STPC Atlas chipset. I can't get a correct display.
In the existing software, we work with 5 planes.
Therefore we use the ''memory bank address high'' register MCR61 (or the ''Page selector register'' XR0E with a 65550 display chip).
The asm code used is:
mov dx, 03C4h
mov al, 61h
mov ah, plane // 0 < plane < 5
out dx, ax
I am trying to convert this code so that it works with the STPC Atlas chipset. Is there an equivalent register in the STPC chipset, or another solution to get a correct display on my screen?
I tried to work with the ''graphics extended aperture register CR21'', with the ''repaint control register'', ''page register 0'', ''page register 1'' (CR1c, CR1d and CR1E) and the corresponding initialisation registers, but I don't find the correct configuration.
In some cases, the display is only in the first 1/5 of the screen, in other cases it is split in different positions on my screen...
I think that the problem, while working with the page registers, is that with the 2 pages (page 0 and page 1), i don't have a linear memory access.
And with the CR21 register i have to set bits 7-6 with ''01'' and the final address is not the same.
any suggestion is appreciated,
thanks,
Simon
