One chip MSX improvement project

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By Marcelo_Zoffy

Supporter (16)

Marcelo_Zoffy's picture

16-01-2014, 19:19

KdL wrote:

hi! you can check the subfolder [scan_codes] of ocm-pld pack v3.2 Big smile

Thank you KdL!! Big smile

By KdL

Paragon (1427)

KdL's picture

16-01-2014, 21:54

ruizander wrote:

well, the bios used was msx2bios.rom released by caro:

md5 msx2bios.rom
MD5 (msx2bios.rom) = 31b91a5a0b4668da78aa36201d42c003

all i've done is overwrite the data with this bios:

md5 expert_ddplus_basic-bios1.rom
MD5 (expert_ddplus_basic-bios1.rom) = d13c1fc9ad4897c322f51aab3ad3b30d

and yes, this really happen: after turning on i press SHIFT on boot gradiente 1.1br screen (normally used to bypass diskbasic) and... tadaaa! i'm on basic...
i really couldn't tell if this msx2bios.rom is modified besides the mod $2C $8D, but i can send you the bios if you want to try... Wink

Ok, good. It is not possible for me to test all existing configurations, I have few time.

By ruizander

Supporter (14)

ruizander's picture

16-01-2014, 22:19

could you give me any directions in order to permit the disk basic to run on this msx1 configuration? i'd really want to learn how to do this... but only looking at this msx2bios.rom i don't know how to begin... all i've done is try-and-error...

By KdL

Paragon (1427)

KdL's picture

17-01-2014, 04:23

Hi ruizander, after a simple test I confirm you that the BIOS is not the problem and any MSX1 version is working very well.

http://www.webalice.it/gnogni/ocm/misc/k32msx1_yen.7z
OCM has a normal boot loading this file from an empty SD-CARD.

The MegaSD BIOS of OCM is a variant of MegaSCSI and when an MSX1 is found the Disk Basic version 1.0 is loaded!
I think it doesn't support FAT16 and I don't know if a FAT12 is possible.
Check these MegaSCSI tools: http://www.big.or.jp/~saibara/msx/ese/

By ruizander

Supporter (14)

ruizander's picture

17-01-2014, 22:00

to simplify the test i did the following: i formatted the sd with fat 12 (720kb) and put msxdos 1.8 and hundra.
but all i saw was a cursor on the blue screen after boot logo. after twice it goes to basic. this disk access works, I could load the game, but it also freezes on splash screen...

well, now i know the problem is not with msx2/msx2+... curiously the very same game works on openMSX with fs-a1wsx...
do you have any hint or work around to better retrocompatibility games/programs?

By KdL

Paragon (1427)

KdL's picture

18-01-2014, 02:15

simply, the v3.2 is not the latest... many improvement are in progress: do not be impatient! Nishi

By ruizander

Supporter (14)

ruizander's picture

18-01-2014, 16:17

ahh, i really can't wait!! Wink
is there something i could help with?

By KdL

Paragon (1427)

KdL's picture

18-01-2014, 21:25

yep! ..there is to redo an entire VDP module!! Tongue Tongue Tongue

By ruizander

Supporter (14)

ruizander's picture

18-01-2014, 23:22

perfect!! i cant do it without your orientation, but i'm sure i can learn!

By KdL

Paragon (1427)

KdL's picture

19-01-2014, 01:31

You should have:
a) a good know of digital electronics;
b) the datasheets of YM V9938, V9958 and V9990;
c) to know VHDL and C/C++ languages;
d) the true MSX machines to do a comparison;
e) time... free time!

A very important bug is that the VDP go too fast: the timing is not accurate.
You can check the subfolder [ocm-pld v3.2\esemsx3\src\video\v9938]
for the better VDP of 1chipMSX (yes, the MSX2 version).

You can read and compare the TH9958 module of HRA but it suffers of other bug.
Suggested by Grauw: also compare the accurate openMSX source code!!! Nishi

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