32x = complete crap?

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RadSil

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I don't know if anyone else has this problem, but I have 2 32x's, and neither one of them are very reliable. I've tried a bunch of different setups, and no matter what combination of Genesis and 32x, all I get is an unstable Genesis that barely plays 32x games. So far the most stable setup I can get is a model 2 Genesis, manufactured around 1993, with my newer 32x. My model 1 Genesis is practically unusable with a 32x attached, most games red-screen (like a bad checksum) or reset often. 32x games don't run on it at all.

But I really want to these questions...

1) anyone else have this problem?

2) (a technical question) does the 32x occupy the Genesis 4mb address space? This would explain the "bad checksum" problem...

3) is the AV in/out cable (the two ended one between the systems) used for communication between Genesis and 32x? If so, what for? This strikes me as terrible design. Correct me if I am wrong, but doesn't this mean that anything passed between the machines is converted to analog, and then back to digital? Isn't this susceptible to interference?

4) am I the only person to ever play Kolibri? :)
 

IceDigger

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I may not be able to answer most of your questions but I can answer one of them...

Yes, I have played Kolobri! Sort of like ecco but with wings.
 

IceDigger

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Open up your 32X, pull out all white ribbon cables, then plug them back in. bad contact on those causes 90% of the problems. also try cleaning the contacts on the cart connector.

As for the cable.. the cable is a simple 1:1 video passthrough cable.. the 32X basically lays its own graphics over the genesis video. that's why you get only the 32X gfx if the cable isn't there. there's no actual data sent over that cable, simply the standard videosignal which is mixed with the 32X signal before outputting it.

and as for Kolibri, I own it and played it a bit.
 

RadSil

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Well, that's strange. I figured you'd know, Arakon. So the only thing that goes over the cable is video data from the Genesis? Is the video completely unmodified (that is, left in its original, ready for output state)? I've never tried using the 32x without the cable attached.

As for the cart contacts, I cleaned those when I saw it wasn't working correctly. They were REALLY dirty. Like "Korean factory" dirty :)

I still think the 32x is shoddy... why else would it need the metal shield plates? That just doesn't seem right to me.
 

IceDigger

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yep, unmodified analog video.

the metal plates are there only to get the interference to a level that complies with whatever standard they got on it, you can leave them out without a prob.
 

RadSil

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Yeah, the plates are probably FCC something or other that basically says "external frequencies can screw you up, but you can't screw up anyone else's". That's the basic rule I think. I'll just be a rebel and leave the plates off from now on, I cut myself on them anyway.
 

ExCyber

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I'm pretty sure that the 32X cartridge occupies the 4MB Genesis cart address space; I don't think there's another suitable place to map it to. On a related note, it's been said that the 32X carts are really just like normal Genesis carts, except that they contain a program that requires 32X (can't verify this since I don't have a 32X yet, but it seems reasonable since the hardware has to accept 32X and Genesis carts). As for a 32X causing games to redscreen, I'd make sure the connectors are clean (one... more... time! :p ), and if it still doesn't work, check the connectors with a continuity tester/multimeter to make sure there that the cart bus isn't broken or shorted (e.g. by conductive dust/residue on the board... stranger things have happened) somewhere inside the 32X. However, that might not uncover heat-related problems.

Edit: In case you want to do deeper checking of the cart interface, here's the Genesis cart pinout, from Rick McTeague's "Sega Genesis Hardware Internals", dated 04/07/1993 (it's on Charles MacDonald's site at http://cgfm2.emuviews.com if you're interested in the whole thing). I'm not sure this will come out right, and IkonBoard doesn't seem to have a code/monospace tag...

The cartridge port pins are numbered A1-A32 and B1-B32, left-to-right, with

the A row toward the back of the Genesis and the B row toward the front.

The "i" and "o" labels describe whether a signal is an input and/or an output

to/from the Genesis.

Signals with an "o" are output from the Genesis to the cartridge.

Signals with an "i" are input to the Genesis from the cartridge.

Pin SignalPin Signal

--------------------------------------

A1 - gnd B1 -?

A2 - +5vB2 i !H_RESET

A3 o a8B3 - ?

A4 o a11B4 o a9

A5 o a7B5 o a10

A6 o a12B6 o a18

A7 o a6B7 o a19

A8 o a13B8 o a20

A9 o a5B9 o a21

A10 o a14B10 o a22

A11 o a4B11 o a23

A12 o a15B12 o VIDEO

A13 o a3B13 o VSYNC

A14 o a16B14 o HSYNC

A15 o a2B15 o HS_CLK

A16 o a17B16 o !C_OE

A17 o a1B17 o !C_CE

A18 - gndB18 o !AS

A19 io d7B19 o CLK

A20 io d0B20 i !DTACK

A21 iod8B21 o ?

A22 io d6B22 io d15

A23 io d1B23 io d14

A24 io d9B24 io d13

A25 io d5B25 io d12

A26 io d2B26 o !LO_MEM

A27 io d10B27 o !RESET

A28 io d4B28 o !LDSW

A29 io d3B29 o !UDSW

A30 io d11B30 i !S_RESET

A31 - +5B31 o ?

A32 - gndB32 i !CART_IN

The most important ones to check (ones that would most likely cause corrupt reads) are the A/D lines, C_CE, C_OE, and CART_IN (not sure that CART_IN would cause data problems, but it might).

(Edited by ExCyber at 10:10 pm on Aug. 15, 2001)
 

RadSil

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ExCyber: Thank you for the nice response. Maybe if I have the time I can investigate deeper; my 32x seems to be working a little better now that I have given it a thourough cleaning. It was really cruddy.

Now, I found something interesting: If I had a capture card I would put it up for you to see, but... anyway, Robocop vs. Terminator always crashes at startup with a 32x on. Always, without fail. Interestingly enough, it has a crash analysis, where it prints out the PC where it crashed, the last executed instruction (I think) and a register dump. It also provides a reason for the crash: I have seen things like "invalid opcode" (which could only be caused by a cartridge that is read incorrectly!) and the more interesting "failure caused by external device". I'm not sure if the "external device" is the 32x or not. Just what mode does the 68k have to be in to capture an invalid opcode? (i.e., why doesn't it just crash hard?)
 

ExCyber

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I'm not sure what "failure caused by external device" refers to. There doesn't seem to be an exception with that name listed in the 68000 User Manual. As for the 68000 catching illegal opcodes, most modern processors have a facility to do so; some element of the internal logic "catches" an invalid opcode, then the processor pretty much treats the event like an interrupt with its own vector so that the program or OS can recognize it as an illegal opcode and react accordingly. Other problems like bus errors, botched interrupt requests, etc. are handled in much the same way.
 

RadSil

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All of this makes me curious as to why more Genesis games didn't take advantage of this functionality... I would assume the debugging versions may have. The only other game I can think of that has a crash report is Flashback, and it's easy to invoke, just do the "run through walls cheat (bug!)". You'll crash the game eventually.

Wouldn't it be possible to have interrupt code that would continue as normal (technically stupid, I know).
 

ExCyber

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Yes, it's possible to have an interrupt service routine that pretty much does nothing, the vector just needs to point to a "return from interrupt" instruction, which would jump back to where the program was (though this might disturb timing-sensitive routines). The Genesis games I've looked at (which isn't that many) seem to have the vectors set up to reset the program on most of the exceptions though. Maybe on some games the debug code is still there, and the vectors just don't point to it anymore? The only reason I can think of right now to do that is to make things like address errors look like a problem with the system rather than a bug in the game program, but then I didn't get much sleep today...
 

Brandon J

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My 32x acted a little screwy on the day I got it. It showed the startup white letters on the black background, then it would freeze. On either of the two games I got for it. I did the usual, blowing on the genesis, the games, the 32x,... It acted a little better, but the games would sometimes freeze during the middle of the game (Doom gave some error message). I cleaned the contacts on the 32x some and it's acted pretty normal since then (about 4 days now).

I was more afraid that it was damaged in shipping than anything else. It's a fun system. I got Space Harrier and Doom.
 

Prosolis

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I don't know about anyone else's experience but my 32X is VERY unstable without the metal connecters in place. Every game would just crash.. I put the metal connecters on, everything was fine. Took em back off (I hate it when friends mess with my crap), and all #### broke loose again. I have a Genesis Model 2 if that helps any..
 

RadSil

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I wasn't really getting any difference from using the metal plates or not; it doesn't seem to matter for me. I still maintain that a 32x works a lot better with a model 2 Genesis... the model 1 still seems unstable even though I have thoroughly cleaned the 32x and the Genesis itself.
 

drmay

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I use a 32x with NO PLATES and it is very stable for me, the only game that won't work with the 32x is Virtua Racing for the Genesis.
 

MYLO

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I never liked 32X. I had the same problem as you RadSil and I got rid of it, like that! I sold it at a flea market, but I still have my Genesis that I never use, I only use my gameboy and dc. 32X is a shit thing, I would just get rid of it, but if not, try to fix it.
 

Fabrizo

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I don't see why you would want to take out the metal plates from the 32x in the first place. I rarely use my one, but for the most part, its a fairly stable peice of equipment. I only own 3 games for it, but I would have to say only one is any good. I think the name of the game was "Shadow Squadron". So basicly I only own a 32x because 1. It lets me be able to say I can play any sega game ever made, sept master system ones, and 2. Because it makes the genesis look neat :)
 
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