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When discussing in another forum(elotrolado.net) about the cartridges that have aditional RAM, one user has posted this picture of "The Terminator" PCB.

Apart from the MPR-14831-F ROM, there's another chip that looks like a RAM chip. I thought that the only games using aditional RAM were "Desert SpeedTrap" and "The Flash". Anyone has any idea about that?

isn't that a mapper chip?

It's what I thought, but according to the specs for that part number, it's a RAM chip...(but maybe I did it wrong)

According to the info here, this is a 2Mbit game: thus it needs a mapper, which I believe is that other chip :)

Well, for size I was sure that it needed a mapper, but most of this era games (post 1990) have the mapper inside the ROM itself...

I think it is clear that it should be RAM by the name of the chip.

Also looking at the code (starting from $3744) helps:

ld a, $08
ld (_RAM_FFFC_), a

It maps cart-RAM into slot 2. I don't see any battery on this pic so I guess it's safe to add the "Embed Extra RAM" tag to this game. Is there any hint about the size of this RAM chip?

According to the Datasheet Archive the partnumber relates to a 32Kb Low Power CMOS Static RAM (DIP format). See attached PDF

DSA2IH00163379.pdf (264.14 KB)

32Kb = 4KB, which seems on the low side. How much of the save file gets touched in an emulator?

Maxim wrote

32Kb = 4KB, which seems on the low side. How much of the save file gets touched in an emulator?

I didn't run anything yet but there's code clearing $bf00 to $bfff and code accessing its data from $8000.

The datasheet says 32768 8-bit words, so it's 32KB...
Also, can this kind of RAM retain contents even when not powered?
I suspect it's NOT used for savegames...

Indeed, the datasheet says 256Kbit. Case matters :)

The game only fills 8KB and seems to slightly rely on data wrapping at that point - it actually emits a couple of bytes extra with values to match the start, and then checks for the address reaching $a0xx to end the loop. I guess it was in the era of larger chips being cheaper due to availability. It's a shame they didn't use more of it.

Something to check: on level 1, at the top left, there is a star if the game has more than 8KB but a black square if it has exactly 8KB (or the upper 24KB is not connected up). What do you see on a real cartridge?

Terminator, The-02.png (4.26 KB)

32KB RAM version

Terminator, The-03.png (4.2 KB)

8KB RAM version

Nice find!

They are all Probe games so they may just use the same engine.

Could some one check any other Probe game PCB's ? Alien 3, for instance...

It's easy enough to tell in an emulator, Alien 3 doesn't use the extra RAM. Which is weird because it seems to have equally large levels.

Author	Message
kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Aditional RAM in SMS Terminator ? Posted: Wed Dec 28, 2016 1:16 pm
kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	When discussing in another forum(elotrolado.net) about the cartridges that have aditional RAM, one user has posted this picture of "The Terminator" PCB. Apart from the MPR-14831-F ROM, there's another chip that looks like a RAM chip. I thought that the only games using aditional RAM were "Desert SpeedTrap" and "The Flash". Anyone has any idea about that?

sverx Joined: 05 Sep 2013 Posts: 3825 Location: Stockholm, Sweden	Posted: Wed Dec 28, 2016 1:40 pm
	isn't that a mapper chip?

kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Posted: Wed Dec 28, 2016 2:02 pm
kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	It's what I thought, but according to the specs for that part number, it's a RAM chip...(but maybe I did it wrong)

sverx Joined: 05 Sep 2013 Posts: 3825 Location: Stockholm, Sweden	Posted: Wed Dec 28, 2016 3:51 pm
	According to the info here, this is a 2Mbit game: thus it needs a mapper, which I believe is that other chip :)

kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Posted: Wed Dec 28, 2016 4:33 pm
kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Well, for size I was sure that it needed a mapper, but most of this era games (post 1990) have the mapper inside the ROM itself...

law81 Joined: 21 Oct 2015 Posts: 303	Posted: Wed Dec 28, 2016 5:39 pm
law81 Joined: 21 Oct 2015 Posts: 303	I think it is clear that it should be RAM by the name of the chip.

Calindro Joined: 14 Apr 2013 Posts: 624	Posted: Wed Dec 28, 2016 6:10 pm
Calindro Joined: 14 Apr 2013 Posts: 624	Also looking at the code (starting from $3744) helps: ld a, $08 ld (_RAM_FFFC_), a It maps cart-RAM into slot 2. I don't see any battery on this pic so I guess it's safe to add the "Embed Extra RAM" tag to this game. Is there any hint about the size of this RAM chip?

Cactushead Joined: 05 Feb 2012 Posts: 10 Location: Amsterdam	Posted: Wed Dec 28, 2016 9:06 pm
	According to the Datasheet Archive the partnumber relates to a 32Kb Low Power CMOS Static RAM (DIP format). See attached PDF DSA2IH00163379.pdf (264.14 KB)

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14738 Location: London	Posted: Thu Dec 29, 2016 9:06 am
	32Kb = 4KB, which seems on the low side. How much of the save file gets touched in an emulator?

Calindro Joined: 14 Apr 2013 Posts: 624	Posted: Thu Dec 29, 2016 9:29 am
Calindro Joined: 14 Apr 2013 Posts: 624	Maxim wrote 32Kb = 4KB, which seems on the low side. How much of the save file gets touched in an emulator? I didn't run anything yet but there's code clearing $bf00 to $bfff and code accessing its data from $8000.

sverx Joined: 05 Sep 2013 Posts: 3825 Location: Stockholm, Sweden	Posted: Thu Dec 29, 2016 9:30 am
	The datasheet says 32768 8-bit words, so it's 32KB... Also, can this kind of RAM retain contents even when not powered? I suspect it's NOT used for savegames...

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14738 Location: London	Posted: Thu Dec 29, 2016 9:59 am
	Indeed, the datasheet says 256Kbit. Case matters :) The game only fills 8KB and seems to slightly rely on data wrapping at that point - it actually emits a couple of bytes extra with values to match the start, and then checks for the address reaching $a0xx to end the loop. I guess it was in the era of larger chips being cheaper due to availability. It's a shame they didn't use more of it. Something to check: on level 1, at the top left, there is a star if the game has more than 8KB but a black square if it has exactly 8KB (or the upper 24KB is not connected up). What do you see on a real cartridge? Terminator, The-02.png (4.26 KB) 32KB RAM version Terminator, The-03.png (4.2 KB) 8KB RAM version

Bock Site Admin Joined: 08 Jul 2001 Posts: 8649 Location: Paris, France	Posted: Sat Dec 31, 2016 10:10 am
	Nice find! They are all Probe games so they may just use the same engine.

kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Posted: Mon Jan 02, 2017 9:09 am
kusfo Joined: 29 Mar 2012 Posts: 886 Location: Spain	Could some one check any other Probe game PCB's ? Alien 3, for instance...

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14738 Location: London	Posted: Mon Jan 02, 2017 9:16 am
	It's easy enough to tell in an emulator, Alien 3 doesn't use the extra RAM. Which is weird because it seems to have equally large levels.

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