Games that may damage PSG chips

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By friguron

Expert (85)

friguron's picture

19-05-2019, 04:45

I'm creating a .rom version for rocket roger... as a good Alligata game, it also has bad 0xFF writing to PSG registers... I've patched the new .rom data with a 0xBF (just one byte). As soon as I strengthen my slot/subslot ram detection routines, I'll publish the 32 KB rom file.

Greetings

By gdx

Prophet (3091)

gdx's picture

12-07-2019, 17:54

I never seen your version. Anyway I converted Rocket Roger to ROM myself. Many bytes had to be patched to fix the I/O port of the PSG. This is a beta version. I hope someone will want to test it.

RRTEST.ZIP

This version works in a primary slot only.

By iamweasel2

Hero (526)

iamweasel2's picture

12-07-2019, 18:10

Great work GDX, I love your conversions to ROM Format. Is there a web site where you put all of your work?

I hope someday you will convert Jackie Chan in Project A (there's a new english translated version with a new color screen done by Slotman) or Polar Star. Smile

By iamweasel2

Hero (526)

iamweasel2's picture

12-07-2019, 18:11

friguron wrote:

I'm creating a .rom version for rocket roger... as a good Alligata game, it also has bad 0xFF writing to PSG registers... I've patched the new .rom data with a 0xBF (just one byte). As soon as I strengthen my slot/subslot ram detection routines, I'll publish the 32 KB rom file.

Greetings

Great, looking forward to see your work Friguron. Smile

By gdx

Prophet (3091)

gdx's picture

16-07-2019, 09:15

I found this short manual on Generation-MSX:

The keys do not match what is indicated. All the versions I found on the net are the same. By cons, the keys are set almost as the Commodore 64 version.

This arrangement seems to me more pleasant to play. The available version had to be modified for this reason. By cons it is not valid for all types of keyboard.

So I will change the setting keys in my way in the next time. I will also add secondary slots support.

By gdx

Prophet (3091)

gdx's picture

17-07-2019, 09:23

The Rom conversion is finish. I make 3 versions. The version using cursor keys supports the joystick. And of course, PSG I/O ports are fixed and should work into a secondary slot.

Download: https://mon-partage.fr/f/Xs4iGyS4/

By Eugeny_Brychkov

Paragon (1107)

Eugeny_Brychkov's picture

04-12-2019, 19:11

I am working on the redesign of the GR8BIT I/O card, it uses GI's AY-3-8910A PSG and ALS157 multiplexers. I decided to try the fault and see what happens.

f3 3e 07 d3 a0 3e ff d3 a1 3e 0e d3 a0 3e 00 d3 a1 18 fe

This program sets port A into output mode, with output value of 0. Default output logical level for the multiplexers is 1 with no joystick connected, thus there's an electrical conflict in the 6 wires.

Under normal circumstances the AY is slightly warm; with this program running it is also warm, but becomes hot in the center of the body when I put my fingers on it and hold for more than 15 seconds. ALS157s are cool. Thus the most affected candidate is AY, and it is cooled well by the free air.

I checked all the service manuals I have for the type of chips machines use - expected to see HC(T)157s (potential cause of the high current -> damage), but all of them use LS157.

Update: tried with YM2149F - absolutely the same result.

Update 2: putting 270 Ohm resistor in the series gives 2.22 V ~ 8.2 mA. Connection without resistor causes current of 16.2 mA per wire. Thus for 6 wires in conflict affected I/Os will consume 100 mA.

By Eugeny_Brychkov

Paragon (1107)

Eugeny_Brychkov's picture

04-12-2019, 22:11

So here're tests on real system with AY:
R=270 Vh=4.75 Vl=0.127 Is=8.2
R=330 Vh=4.75 Vl=0.131 Is=7.08
R=470 Vh=4.72 Vl=0.140 Is=5.38
R=1k Vh=4.70 Vl=0.162 Is=2.88

Higher value will affect the pulse edge's slope, so I choose 470. YM shows Is=5.4 mA, and Is=3.06 mA if YM's output is high and '157 output is low. Thus max current under electrical conflict is 6*5.38 ~ 32 mA.
Trigger tested operational.

By Alexey

Guardian (2461)

Alexey's picture

09-12-2019, 18:20

So, is the story of psysically damaging the chips with configuring in an out at the same time a hoax?

By gdx

Prophet (3091)

gdx's picture

10-12-2019, 02:00

Unclear because those who say that may damage PSG chips, they say that is possible only for some MSX. My experience has only shown that can cause bugs in the control on some MSXs. It would take the diagrams of all MSXs to be sure.

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