Topic: Defective (original Irem) R-Type  (Read 18838 times)

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Offline Womble

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Re: Defective (original Irem) R-Type
« Reply #30 on: March 27, 2011, 12:47:04 PM »
Yep that's what I have, still impressed with it too. eBay is the best price I could find but mine came from hong kong, the only local supplier i found had added $150 to the price, so eBay it was. It tests most common SRAMs but isn't much use with old DRAMs alas.
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Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #31 on: March 27, 2011, 02:16:21 PM »
Hmmmm, sometimes u just gotta take a quick decicion, I think I'll buy one...


Offline Womble

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Re: Defective (original Irem) R-Type
« Reply #33 on: March 28, 2011, 01:29:29 PM »
I have heard bad things about Willems, apparently it is actually hard to buy a real one as the market is flooded with cheap knock offs.

The TOP one should fit the bill tho, never used one myself however. It will test the 2018s if you can get them off the board in one piece too, just choose the 6116 SRAM test.
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Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #34 on: March 28, 2011, 01:33:29 PM »
Just found that the Top might not run in Win7 };-(.
Shame as it's pretty cheap...

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #35 on: March 28, 2011, 01:40:34 PM »
Aha! But here's a Win7 version of the software };-P

http://www.topwin6.com/Soft.html

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #36 on: March 28, 2011, 06:20:50 PM »
Hmmm, I see that the Top853 doesn't support eg M5L27512K (which is on my R-Type) but do support M5M27512; what's the difference and are they interchangeable in a circuit?

http://www.top2048.com/gb/DeviceList/top853.txt

Sorry if my questions are too n00by };-D

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #37 on: March 28, 2011, 06:39:25 PM »
i would say these devices are compatible with each other, just another 27512
could be wrong with this, im quite often wrong about stuff  :D

as for too nooby, i dont think you will find any of that eliteist bullshit on this forum like there is on so many other forums out there. Ask away, where else are you going to learn stuff.

Offline AndyRCM

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Re: Defective (original Irem) R-Type
« Reply #38 on: March 28, 2011, 06:52:32 PM »
as for too nooby, i dont think you will find any of that eliteist bullshit on this forum like there is on so many other forums out there. Ask away, where else are you going to learn stuff.

I couldn't agree more Jon - we are all here to help each other on this forum! I learn so much from all of the talk on here! ;)

A
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Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #39 on: March 28, 2011, 07:42:54 PM »
...as for too nooby, i dont think you will find any of that eliteist bullshit on this forum like there is on so many other forums out there...
Believe me, there are sooo many arcade-techy-wizz-hot-shots out there who are NOT willing to help a beginner:
'Just send it to me, I'll fix it for you for 50 quit', but will not tell you what I've done to make it work!
...that's the deal...in Denmark anyway...

I simply LOVE you guys! };-D
« Last Edit: March 28, 2011, 09:16:43 PM by Elgen »

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #40 on: March 28, 2011, 08:04:55 PM »
ive had my fair share of text based bashings on other forums when I first started out, never really went back to them after that. Aussie Arcade is another good one.

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #41 on: March 28, 2011, 08:08:51 PM »
I'll keep that in mind...};-D

Offline moggy

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Re: Defective (original Irem) R-Type
« Reply #42 on: March 28, 2011, 09:44:29 PM »
Hi Guys
I know nothing about arcade boards but I really love reading Wombles "walkthroughs" :)

A great way to learn and enjoyable as well.

Great stuff.

Regards Moggy

Offline Womble

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Re: Defective (original Irem) R-Type
« Reply #43 on: March 28, 2011, 11:56:03 PM »
Oooh - much love!  ;)

Yeh some forums are downright snarky, I was lucky to find Aussie Arcade when I started out. Actually it was reading "ArcadeKings" repair logs on AA that got me in to board repair coz it sounded like fun. What AK failed to mention was how damn addictive it is.

Anyway I was a beginner not that long ago so am very happy to help people heading down the same road, have said this before I know, but my repairlogs are written with that in mind. Most repairlogs out there just say that fault X was cured by replacing chip Y, next to useless as even if you have the same board and a similar fault it is highly unlikely to be the same component that is causing it. What I found lacking were threads that showed the troubleshooting process itself, which is where the real knack lies.

Anyway - to the ROM question. Porchy is right in that they are all variants of 27c512 eproms, the vast majority of variations are just what that manufacturer decided to call their type of chop. M5L is what Mitsubishi called theres, MBM = Fujitsu, D=NEC, AM=AMD etc etc. Some have the c between the 27 and the kbit count figure (ie 512kbit) and some don't. The 27 just means it is an EPROM, eraseable and reprogrammable, the C means its is CMOS based.

Naming conventions aside the pinouts are the same, if you track down the exact datasheet for one chip and a datasheet for another 27c512 they will be indentical except for the fact that some makers name the pins differently.

Enable pin - E or G or CE
Chip Select - S or CS
Data pins - D0-D7, or D1-D8, or O 0-O7, or O1-O8
Address bus - A0-A15, or A1-A16
Program pin - P, or VPrg

So at a glance it might look like a different pinout but in reality its the same by different names.

There are a couple of caviates tho...

1) This works up until the 1Mbit chips, then things go bonkers, for a number of reasons the pin scheme used for years started to become a bit of a problem and when they went from kbit to mbit they decided enough was enough. So suddenly you have 27c1000, 27c1001, 27c010, 27c100 so you do need to find the datasheets for those as some manufacturers did their own thing.

2) Programming - a 27c512 is a 27c512 is a 27c512, but that is for reading only, when it comes to writing you need to pay attention to the programming voltages. There is a pin on the EPROM that sets it into program mode, the voltage requirements are specific to that chip, so choosing another 27c512 that your burner supports may mean you program with the wrong voltage, which will either fail to work, or smoke the ROM. Standard Vprgs are in the 12-12.75v range, but some (and I am looking at you AMD) decided that 21v was a great idea, especially as they didnt stick with it, so when I choose the right chip on my VP280 it can provide a nice 21V to a chip that was only expecting 12.5V - ZAP! So, you can chose any 27C512 you like to read, but if you are writing you need to double check the Vprg is correct for the target chip. Most burners allow you to modify the parameters so you should be able to tweak the Vprg after selecting a chip from its known library.

3) Other diagnostics, my burner will tell me if any legs are out of spec, it is possible that this will give erroneous results if the chip is not the same as the one selected in the app, never seen it but it is possible I suppose, it wont damage anything but its worth bearing in mind. So if your burner knows about the chip you are trying to read or write you might as well chose it, but if you are writing to the chip it pays to check the Vreg it is planning on providing before you hit the burn button even if you have selected the exact chip.

A side note is that the USB port can only provide 5V to connected devices which is fine for reading chips and doing SRAM and TTL tests, but when you come to program a chip you will need to plug in the external power supply as the USB bus can't provide the volts for the Vprg pin. Most programmers are highly Chinglish in nature and mine helpfully tells me "Power supply require" every time I select a ROM. If I was going to burn one then it would be required, but for dumping chips it isn't.

/brain dump off

« Last Edit: March 29, 2011, 12:03:40 AM by Womble »
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Offline Phu

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Re: Defective (original Irem) R-Type
« Reply #44 on: March 29, 2011, 12:38:25 AM »
If I might humbly fill a few gaps in that fine knowledge sir :)

Some EPROMs have separate /PGM (program enable) and VPP (programming voltage) pins, and some just rely on VPP being at programming voltage to program. On those that have a separate /PGM pin, it should be held high when being read.

21V was the original programming voltage level back in the early days of EPROMs. Later (notably the CMOS types) can work with 12.5V.

There are such things as OTPROMs (One Time Programmable Read Only Memories) that are basically EPROMs without an erase window. These tend to have the same part numbers as proper EPROMs (e.g. 27C256) but are obviously not erasable. Thus second-hand OTPROMs are completely useless as they can't be reprogrammed.

Some *really* old EPROMs have a 25 prefix, e.g. 2532s and 2516s. These are 21V programmable and have a different pinout to their 27 counterparts.

Oh, and lastly... some of those really big EPROMs have a sneaky dual-access mode where they can either be read as 8bit, or as 16bit at half the address capacity. These have 8 extra data lines and a mode select line indicating how they will be read.

-- Richard
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