Dumping/reverse engineering MSX models thread

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By pgimeno

Champion (292)

pgimeno's picture

20-04-2020, 00:08

Interesting, these SHA256's don't match the ones I have. I wonder if it's another revision.

By bsittler

Master (243)

bsittler's picture

20-04-2020, 01:28

pgimeno wrote:

Interesting, these SHA256's don't match the ones I have. I wonder if it's another revision.

Care to inspect? I've attempted to share the dumps, please let me know if the link does not work:
https://www.dropbox.com/sh/1abvsr0xu5pk18y/AAA_pd9pL1oHAasFK...

(You can ignore the differently-named files, those are identical contents but a different dumping method. I didn't keep the third set since the contents were also identical that time.)

By pgimeno

Champion (292)

pgimeno's picture

20-04-2020, 01:51

Thanks!

My Arabic ROM:

$ strings ax-150_arabic.rom | head
ABb@\D
\zerhrlba
Y+(MSX
 system
Y,(version  1.01
Y/&Copyright 1986 by
Y1$Microsoft & Alalamiah
"""PPP  "
HHH($#
  @@  EEE

Your Arabic ROM:

$ strings sakhr-ax150-arabic.rom | head
ABG@
Zcc[f[jK_
N#F#^#V#
^#V#
MSX BASIC version 1.0
Copyright 1983 by Microsoft
 version 1.02 Copyright
Y# 1986 by Microsoft & Alalamiah
MSX DISK BASIC
color 

From that, it appears that your ROMs are version 1.02 of the Arabic ROM while mine are version 1.01.

The BIOS don't have any version numbers. These are the only differences (the - are my ROM, the + are yours):

--- ax-150_basic-bios.rom
+++ sakhr-ax150-bios.rom
@@ -1,4 +1,4 @@
-000000 f3 c3 60 01 bf 1b 98 98 c3 83 26 00 c3 b6 01 00  >..`.......&.....<
+000000 f3 c3 d7 02 bf 1b 98 98 c3 83 26 00 c3 b6 01 00  >..........&.....<
 000010 c3 86 26 00 c3 d1 01 00 c3 45 1b 00 c3 17 02 00  >..&......E......<
 000020 c3 6a 14 00 c3 5e 02 00 c3 89 26 91 11 00 00 00  >.j...^....&.....<
 000030 c3 05 02 00 00 00 00 00 c3 3c 0c c3 9d 04 c3 9d  >.........<......<
@@ -19,8 +19,8 @@
 000120 c3 7e 16 c3 09 18 c3 c7 18 c3 cf 18 c3 e4 18 c3  >.~..............<
 000130 7a 19 c3 3d 0f c3 7a 0f c3 4c 14 c3 4f 14 c3 49  >z..=..z..L..O..I<
 000140 14 c3 52 14 c3 8a 14 c3 8e 14 c3 5f 14 c3 63 1b  >..R........_..c.<
-000150 c3 70 14 c3 74 14 c3 68 04 c3 ff 01 00 00 00 00  >.p..t..h........<
-000160 3e 02 d3 99 3e 89 d3 99 c3 d7 02 00 00 00 00 cd  >>...>...........<
+000150 c3 70 14 c3 74 14 c3 68 04 c3 ff 01 00 00 ed 57  >.p..t..h.......W<
+000160 f5 78 e6 3f c3 4f 02 f1 e2 6c 01 fb 08 d9 c9 cd  >.x.?.O...l......<
 000170 ad 01 20 52 e5 cd 99 01 e3 cd be 7f 18 0f cd ad  >.. R............<
 000180 01 c2 e1 01 d1 e5 cd 99 01 e3 cd c4 7f e3 f5 7d  >...............}<
 000190 d3 a8 7c 32 ff ff f1 e1 c9 f5 3a ff ff 2f 67 e6  >..|2......:../g.<
@@ -34,8 +34,8 @@
 000210 23 d5 dd e1 d1 f1 e3 d9 08 fd e5 f1 dd e5 e1 cd  >#...............<
 000220 7e 02 fa 2e 02 db a8 f5 a1 b0 d9 c3 8c f3 cd a3  >~...............<
 000230 02 f5 fd e1 e5 c5 4f 06 00 7d a4 b2 21 c5 fc 09  >......O..}..!...<
-000240 77 e5 08 d9 cd 17 02 d9 08 e1 c1 d1 78 e6 3f b1  >w...........x.?.<
-000250 f3 d3 a8 7b 32 ff ff 78 d3 a8 73 08 d9 c9 cd 7e  >...{2..x..s....~<
+000240 77 e5 08 d9 cd 17 02 d9 08 e1 c1 d1 c3 5e 01 b1  >w............^..<
+000250 f3 d3 a8 7b 32 ff ff 78 d3 a8 73 c3 67 01 cd 7e  >...{2..x..s.g..~<
 000260 02 fa 6b 02 db a8 a1 b0 d3 a8 c9 e5 cd a3 02 4f  >..k............O<
 000270 06 00 7d a4 b2 21 c5 fc 09 77 e1 79 18 e0 f3 f5  >..}..!...w.y....<
 000280 7c 07 07 e6 03 5f 3e c0 07 07 1d f2 88 02 5f 2f  >|...._>......._/<

I can't make heads or tails from it without disassembling, but if it is newer, it probably has some kind of bugfix.

What serial number is yours? Mine is 011501.

By bsittler

Master (243)

bsittler's picture

20-04-2020, 03:50

I am a little bit surprised to see "DISK BASIC" in mine, given the lack of disk drive in this model!

The Gregorian year listed in Indian numerals on (left) end of the second line of the Arabic menu screen for mine is 1986 (١٩٨٦), what's the year shown in yours?

And indeed, the version you mention from my dumps is the one shown in the start-up screen and when BASIC is started:

MSX BASIC version 1.0
Copyright 1983 by Microsoft
MSXصخر version 1.02 Copyright
1986 by Microsoft & Alalamiah

Ok

I put video captures (apologies for the low capture quality!) and photos of the display into the shared folder

Mine is serial number 016381

Also "DEL" was not even necessary, and might have no effect — this combination and ordering of cartridges allows a boot from MicroSD card in the MegaFlashROM SCC+ SD while still having access to Arabic mode in BASIC. The "1" is still needed to use GETROM.BIN with disk saving, of course.

By Manuel

Ascended (18064)

Manuel's picture

20-04-2020, 08:32

Can you make pictures of the inside? Maybe the hardware is also different.

By pgimeno

Champion (292)

pgimeno's picture

20-04-2020, 11:39

bsittler wrote:

I am a little bit surprised to see "DISK BASIC" in mine, given the lack of disk drive in this model!

It's quite possible that it incorporates fragments of the Disk BASIC ROM, regardless of not having a disk drive.

bsittler wrote:

The Gregorian year listed in Indian numerals on (left) end of the second line of the Arabic menu screen for mine is 1986 (١٩٨٦), what's the year shown in yours?

The same.


bsittler wrote:

And indeed, the version you mention from my dumps is the one shown in the start-up screen and when BASIC is started:

MSX BASIC version 1.0
Copyright 1983 by Microsoft
MSXصخر version 1.02 Copyright
1986 by Microsoft & Alalamiah

Ok

For me it shows the same but with 1.01.


bsittler wrote:

Mine is serial number 016381

Aha, that confirms that indeed it's a later model. Thanks!

By bsittler

Master (243)

bsittler's picture

22-04-2020, 02:35

I'll attempt this over the coming weekend, but it may be difficult — the plastic case is very brittle and was already somewhat disintegrated when I received the machine. Also I lack photography skills and equipment.

What specifically would you like to see pictures of? Will it involve opening/lifting the RF shield?

By Manuel

Ascended (18064)

Manuel's picture

22-04-2020, 08:41

The general lay-out of the main PCB, the revision number of it (to compare against pgimeno's), the texts on the chips.

By pgimeno

Champion (292)

pgimeno's picture

25-04-2020, 01:13

bsittler, the case is held by clips, it has no screws. Some are on the top of the bottom side and others on the sides. You don't need to remove the keyboard membrane leads if you are careful.

You'll need to unscrew the keyboard and tip it upside down carefully to allow you to take an unobstructed picture.

Edit: See pic: http://www.formauri.es/personal/pgimeno/temp/AX150_Clip_loca...

By Patrick

Supporter (14)

Patrick's picture

26-04-2020, 18:07

I have dumped the ROM of my Olympia PHC-2 with the SaveROM 1.2 tool.
The file is here.

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