REQUEST: G400 register level programmers to assist

[Nicole Kaiyan]

I am looking for someone who knows the G400 at the hardware register level, to look over the values for a particular display mode I wish to switch the G400 into and confirm or correct values where they are wrong, and then to look at the values for drawing a line in PowerMode too, a bit later on.

If someone can assist I would be, well more than grateful since it is a frustrating experience to say the least and many a morning has seen the dawn happen whilst trying in vain to get the code to work!

Just to fill you in, I am programming in assembler A386, from MSDOS, with a protected mode switching routine I have written that definitely works, it is just the G400 mode switch code and/or drawing code that does not once in protected mode.

Hear from you shortly

Nicole
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__________________________________________________ _________________________
Nicole Kaiyan
Adelaide, AUSTRALIA

email: nk@vygotski.philosophy.adelaide.edu.au


Begin forwarded notes:

Desired display mode is Standard Vesa Mode 1024 x 768 at 60Hz, which according to my notes, has values as follows:
* pixel clock freq.(kHz) 65000
* width 1024
* h-sync pulse start 1048
* h-sync pulse end 1184
* total pixels in line 1344
* height 768
* v-sync pulse start 771
* v-sync pulse end 777
* total lines in frame 806
* sync polarity 0

Now based on the supplied values and having looked over the G400 specs many times I arrive at the following values:


register decimal hex notes
__________________________________________________ ____________________________
vtotal 804 324h 806 lines - 2
vdispend 767 2FFh 768 lines - 1
vblkstr 767 2FFh 768 - 1
vblkend 00100101-base2 804(vtotal)+1 = 805(325h) AND FFh
vsyncstr 771 303h
vsyncend 1001-base2 777(309h) AND 0Fh

htotal 163 A3h 1344 pixels/8=168 characters - 5
hdispend 127 7Fh 1024 displayed pixels/8=128 - 1
hblkstr 127 7Fh 1024/8 = 128 - 1
hblkend 0100111-base2 163(htotal)+4 = 167(A7h) AND 3Fh
hsyncstr 131 83h 1048/8 = 131
hsyncend 10100-base2 1184 pixels/8 = 148(94h) AND 1Fh

startadd 0
offset 256 100h 1024pixels*32bpp*1/128
maxscan 0 1X horizontal zoom
linecomp 768 300h

hsyncpol 0 based on 768 lines
vsyncpol 0 based on 768 lines

hsyncdel 00
hdispskew 00
bytepan 00
conv2t4 0
dotclkrt 0
dword 0
wbmode 1
hsyncsel 0
selrowscan 1
cms 1
maxhipri 010 (2)
hiprilvl 101 (5)

mgamode 1
csyncen 0
scale 011 32-bits/pixel
interlace 0

depth 100 32bits/pixel Direct Color
clksel 11
pixclksl 01

pixpllm 2 PIXPLLM/N/P (C register set)
pixplln 28 65.250MHz
pixpllp 3 = 27MHz * [28+1] / [[2+1][3+1]]
pixplls 0

syspllm 2 SYSPLLM/N/P
sysplln 27 252MHz
syspllp 0 = 27MHz * [27+1] / [[2+1][0+1]]
sysplls 3

gclksel 01 SYSPLL 252MHz
gclkdiv 011 divide by 2 ---> GCLK 126MHz
gclkdcyc 0000 none
mclksel 01 SYSPLL 252MHz
mclkdiv 100 divide by 3/2 ---> MCLK 168MHz
mclkdcyc 1011 duty cycle correction(?)
wclksel 01 SYSPLL 252MHz
wclkdiv 011 divide by 2 ---> WCLK 126MHz
wclkdcyc 0000 none
__________________________________________________ ____________________________
Notes:

vblkend [8-bit] = (vblkstr - 1 + vblk signal width) AND FFh
= (vtotal + 1) AND FFh
vsyncend [4-bit] = (vsyncstr + vsync signal width) AND 0Fh
hblkend [7-bit] = (hblkstr - 1 + hblk signal width) AND 3Fh
= (htotal + 4) AND 3Fh(?)
hsyncend [5-bit] = (hsyncstr - 1 + hsync signal width) AND 1Fh

htotal > 0
vtotal > 0
htotal > hdispend
htotal - bytepan[00] + 2 > hdispend
hsyncstr > hdispend + 2
hblkend > hsyncstr + 1

htotal + 5 = hblkend + 1
hdispend + 1 = hblkstr + 1

VESA standard mode 1024 x 768 at 60Hz:
- Vertical
total 806
display end 768
blank start 768
sync start 771
sync end 777
blank end 805

- Horizontal
total 1344
display end 1024
blank start 1024
sync start 1048
sync end 1184
blank end 1348

blanking signal width is derived
horizontal = htotal + 4 - hblkstr = 1344+4-1024= 324 (or 40 1/2 chars)
vertical = vtotal - 1 - vblkstr = 806-1-768 = 37

sync signal width is defined
horizontal 136 pixels (or 17 chars)
vertical 6 pixels
__________________________________________________ ____________________________

Further notes:

All I seem to get are vertical stripes, about 7 of them regularly spaced across the screen, the monitor appears to have picked up a stable signal but I cannot get anything other than this!

[Ashley]

vtotal 804 324h 806 lines - 2
vdispend 767 2FFh 768 lines - 1
...

Well, this is probably not going to be very helpful, but just in case you meant this literally... You do realize that all these registers are only 8 bits wide? (You can't write 324h to the vtotal register, or you'll end up, not with 806 lines, but with only 38.)

[Greebe]

Nicole, gbm's isp has been offline since last week and says he'll help first chance he gets