Dragon's Lair Fans - Arcade Lifestyle
General Chat => Technical Area => Topic started by: anunaki on July 13, 2015, 10:47:18 PM
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Hi,
Can someone please explain in a clear way to me what a flip flop IC, i.e. SN74LS74AN does?
Cheers
Patrick
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The internet is new encyclopedia of all human knowledge ;)
https://en.wikipedia.org/wiki/Flip-flop_(electronics)
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Hi,
Can someone please explain in a clear way to me what a flip flop IC, i.e. SN74LS74AN does?
Cheers
Patrick
It is a little box that hold 1 bit of data ... So it contains either a 0 or an 1. In this case the chip contain two seperate boxes. Further more it has some rules to show what is in the box, when to show it, when to change it.
A kind of digital magic 😄
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A FlipFlop is an one bit memory cell. It's either Flip or Flop. ;D
It's used to store an information, for example a video signal bit until it has been written on the screen. There is input data (D) that is stored when a clock pules appears, and output data (Q) that represents the stored data. After storing, output data doesen't change, even if input data is changing.
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Of course i read Wikipedia and other sites before asking
Thx guys hopefully this puts me in the path of understanding
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Of course i read Wikipedia and other sites before asking
Thx guys hopefully this puts me in the path of understanding
Are you looking into a specific game or problem?
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I have an Graphical issue with my wonderboy Pcb.
There is a daughterboard that only has one of these and 4 eproms
When I remove this daughterboard the issue stays exactly the same so I figured this might be the cause
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A FlipFlop in combination with EPROMs might store an address bit... just a guess...
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Well since the IC is already socketed I'll try replacing it
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I have an Graphical issue with my wonderboy Pcb.
There is a daughterboard that only has one of these and 4 eproms
When I remove this daughterboard the issue stays exactly the same so I figured this might be the cause
I guess it is a memory selector. You have two drawers 00, 10, 01, 11 kan be stored in this ic so it tells which eprom to read from. i don't think this is your problem. You say the problem stays even after removing the board? So the problem and the board are not connected or the problem is that the board is totally not working. I would look elswere. An failing eprom select would most likely crash the program and the game would fail completely. But this is a bit a guess without knowing the exact problem and with no schematics.
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the issue is that all sprites are missing, the programm is running fine including the inputs and sounds, this happened over night... one day it was working next day it wasn't
I guess I need to to the basics 1st and check the eproms. Unfortunately I don't have or know a schematic available for this.
I just feel sad about this: Finally I have this PCB and it already broke down on me
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did you check the voltages ?
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Thats a good suggestion because these boards have loads of chips.
Also, is it a System 1 or 2 boardset ?
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system 1
Well, the voltage from my NAC never gave any trouble and the WB bootleg works just fine. At the edge connector it is 5.05V
I need to redo my workbench so I can properly measure voltages on the chips.
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Mm, I guess a WB bootleg has about the same amount of chips so I expect it to not be the problem.
Still a good idea to measure on the ROM board I guess......surprised this is a Z80 game ....somehow I always thought it was 68000 probably because of the ST/Amiga like graphics and time of release (1987).
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I'm a complete noob, but measuring voltages I can do and I will
My guess was that the eproms containing the sprites aren't accessed and this IC is in between (or so it seems to me). I completely desoldered the daughterboard (some wires are there from the factory) and the result didn;t change at all
I actually can play the game blind (so without the moving objects like the boy, the fruits and the villains) and get sounds FX + die at collision
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measure a 7400 series chip somewhere on the board between pin 7 and 14.
preferably one that is far from the edge connector.
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Cool advice! Thanks Etienne!
When measuring a chip, I was always using my monitor chassis instead of pin 7. :oops:
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yes great tip indeed, I do this also. Picked this up from a Randy Fromm video (whitch was also a tip from Etienne btw)
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Since its a Z80 board I -could- hook it up to my Fluke 9100a.....however....we need info:
- memory map of Wonder Boy, that is, where are The ROMs located ?
- signature.....highly unlikely to find those for the 9100A but we could try the regular CRC32. Andy from the UK wrote a program to get this number with the 9100A.
now, if you find the memory map.....:)
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mame is always good for memory-maps...
the system1-memory map
https://github.com/mamedev/mame/blob/master/src/mame/drivers/system1.c
starting at line 732
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Do you have a logic probe?
I would check the sprite ram first. With a rom failure the game probably would not start at all. The game is playing so the problem is most likely close to the output side not at the rom side.
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Yes I do Have one.
I'm almost done reordering my workbench so then I can properly test the basics 1st.
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Do you have a logic probe?
I would check the sprite ram first. With a rom failure the game probably would not start at all. The game is playing so the problem is most likely close to the output side not at the rom side.
Im not familiar with Wonderboy hardware but usually there are separate program ROMs and Graphics ROMs Leo, so if the Graphics ROMs are bust but the program ROM still Ok the game plays but you don't see the corresponding graphics. At least that's how it works on Galaxian.
Jochen, thanks and I know but I wanted to keep a small challenge for Patrick ;)
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1) I replaced the 74ls74 with a brand new one and the image is nice and clean again (this was distored 1st), but still no sprites
2) I measured the voltage on the 74LS74 on the daughterboard and it's a nice 5.02V
no I'm going to check the eproms
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Hmmm, all 4 eproms are filled completely with FF
this doesn't look right, this menas they are empy I guess??
I'm going to look if I can reprogram them
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I also know for sure now that these are the sprite eproms, thanks to the MAME rom images
I'm clearing the eproms now, hopefully they still work. If not, I need to find some 27128 eproms
edit: well, the eproms are dead I think so I need to get some new ones
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that sounds O.K., 0xFF in sprite data is often displayed as transparent color... could be a reason that there were no sprites at all.
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still strange how this happened, maybe because of the failing 74ls74
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Funny, just discussed about failing EPROMS and trying to wipe and reprogram them with Speleo....he said it's pointless in all cases he encountered bad EPROMS had died physically, it's not a case of loosing the programming through UV light.
I had tried with one from Chris's Tron board and same result. The dead 74 might indeed be the cause.
I have quite a few 27128's On stock IIRC.
Good work by the way !
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thanks, I ordered some from ebay germany
I think i had a major breaktrhough in my perception of how a processor works with memory locations this night. Now it seems really easy, almost too easy to be true.
Is it really a matter of accessing a memory location through the address lines, telling it what to do using the control lines and then read or wright to/ from the specific location over the data lines?
So the circuit/ pcb is designed to let the CPU do this and some of the logic ICs are actually just enabling this proces? So when the CPU wants to access a certain address, the logic ICs surrounding it needs open the way of the data lines as well.
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thanks, I ordered some from ebay germany
I think i had a major breaktrhough in my perception of how a processor works with memory locations this night. Now it seems really easy, almost too easy to be true.
Is it really a matter of accessing a memory location through the address lines, telling it what to do using the control lines and then read or wright to/ from the specific location over the data lines?
So the circuit/ pcb is designed to let the CPU do this and some of the logic ICs are actually just enabling this proces? So when the CPU wants to access a certain address, the logic ICs surrounding it needs open the way of the data lines as well.
Yep no magic, an eprom is just a big 'letterbak' where you can put marbles in, white ones and black ones 😄
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Ok got the EPROMs and programmed them
Same issue still: the distorted graphics and missing sprites
This is a good opportunity to learn how to fix a pcb
I'll need to start probing some ram I think. 1st I need to setup my test bench
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So start to check if sprite data is added to the videoram and work your way back towards the sprite ram and if needed further back towards the roms..... Enjoy.
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Do you know which version of Wonderboy you have Patrick ?
There is quite a few of them:
http://tech.quarterarcade.com/tech/game.aspx?g=3438
There's not-encrypted, old encrypted, new encrypted and more....
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Yes it's wonderboy set 2 with the custom
System 1
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Yesterday andre and I looked at this PCB together. The plan was to hook it up to the Fluke 9100 and check the specific addresses.
When looking at the map:
ROM_START( wboy2 )
ROM_REGION( 0x10000, "maincpu", 0 )
ROM_LOAD( "epr-7587.129", 0x0000, 0x2000, CRC(1bbb7354) SHA1(e299979299c93981f5d28a1a614ad644506911dd) ) /* encrypted */
ROM_LOAD( "epr-7588.130", 0x2000, 0x2000, CRC(21007413) SHA1(f45443a49e916465e5c8a8b348897ab426a897bd) ) /* encrypted */
ROM_LOAD( "epr-7589.131", 0x4000, 0x2000, CRC(44b30433) SHA1(558d799c8f48f76c651f19e2a81160eb78ac6642) ) /* encrypted */
ROM_LOAD( "epr-7590.132", 0x6000, 0x2000, CRC(bb525a0b) SHA1(5cd4731e0adfb5c660144eccda759e12a30ce78e) ) /* encrypted */
ROM_LOAD( "epr-7591.133", 0x8000, 0x2000, CRC(8379aa23) SHA1(da47e0150b724a00878ef5f953fa6ac80bb27d8d) )
ROM_LOAD( "epr-7592.134", 0xa000, 0x2000, CRC(c767a5d7) SHA1(a4e8d6a8278ac2227bde8c24d45aa7ab2a273579) )
ROM_REGION( 0x10000, "soundcpu", 0 )
ROM_LOAD( "epr-7498.120", 0x0000, 0x2000, CRC(78ae1e7b) SHA1(86032f443359b0bb2766e33024ed2e320aa9bc84) ) /* epr-7498.3 */
ROM_REGION( 0xc000, "tiles", 0 )
ROM_LOAD( "epr-7497.62", 0x0000, 0x2000, CRC(08d609ca) SHA1(11799e9ef7e6942b304f132b404bff3ed44d524b) ) /* epr-7497.82 */
ROM_LOAD( "epr-7496.61", 0x2000, 0x2000, CRC(6f61fdf1) SHA1(21826aebf5835b9f3d9c467c8647809c1bc0d01f) ) /* epr-7496.65 */
ROM_LOAD( "epr-7495.64", 0x4000, 0x2000, CRC(6a0d2c2d) SHA1(8c21d7f0768e8dda2b7185f3c510cae4229a4a2e) ) /* epr-7495.81 */
ROM_LOAD( "epr-7494.63", 0x6000, 0x2000, CRC(a8e281c7) SHA1(a88b80a7b94ab1401bbf28d7707fdf28a5505127) ) /* epr-7494.64 */
ROM_LOAD( "epr-7493.66", 0x8000, 0x2000, CRC(89305df4) SHA1(7a5098624769a31e7512f56831e818bce6a18871) ) /* epr-7493.80 */
ROM_LOAD( "epr-7492.65", 0xa000, 0x2000, CRC(60f806b1) SHA1(f91e5868a455dff2bce3c2891a7cfd648957cd73) ) /* epr-7492.63 */
ROM_REGION( 0x10000, "sprites", 0 )
ROM_LOAD( "epr-7485.117", 0x0000, 0x4000, CRC(c2891722) SHA1(e4e11c0e9bd0dc121c25349493f2b13d2ff8c807) ) /* epr-7485.3 */
ROM_LOAD( "epr-7487.04", 0x4000, 0x4000, CRC(2d3a421b) SHA1(d70440a8703ccface3212cd9544c950b36263e8c) ) /* epr-7487.1 */
ROM_LOAD( "epr-7486.110", 0x8000, 0x4000, CRC(8d622c50) SHA1(9a76a50204c618347d3e8eee6cda841becd906eb) ) /* epr-7486.4 */
ROM_LOAD( "epr-7488.05", 0xc000, 0x4000, CRC(007c2f1b) SHA1(c2f1376144a49d20cb35384648e06d06978474c1) ) /* epr-7488.2 */
ROM_REGION( 0x0100, "proms", 0 )
ROM_LOAD( "pr-5317.76", 0x0000, 0x0100, CRC(648350b8) SHA1(c7986aa9127ef5b50b845434cb4e81dff9861cd2) )
You see there are 4 maps, but there are only 2 CPUs.
While probing the Sprite Eproms (and the flip flop IC) on the daughterboard, we could see nothing was happening.
Can anyone explain how you can have 4 times an address range while you only have 2 CPU?
And I'm really looking for a SEGA system 1 schematic, so if anyone has it, please share it with me.
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I found the schematics for Star Jacker, this is a SEGA System 1 game