From: clay@supra.com (Clay Cowgill) Subject: TECH: I,Robot questions... Date: 1997/02/06 newsgroups: rec.games.video.arcade.collecting Fine. I couldn't stand it anymore so I started working on my I,Robot finally. Datapoint #1: At some point in the 80's they used escaped mental patients to carry out I,Robot power supply repairs. My guy must have missed his last couple doses of meds, since the PSU is totally #$!@#ed. (The solid core 600V 8ga wires coming up from the pedestal should have tipped me off... ;-) Datapoint #2: I ripped the whole @#!$!@! mess out. Anyway, I can deal with the PSU, but I have a couple questions about the PCB. Self test is giving me a "bad ROM" error code. The code is: UNP8 1EF Now, I take this to mean EPROM 1EF on the CPU board, but does anyone know what the UNP8 could mean? (I didn't find any help in the manual on that one.) I've got some little flicker dots in the polygon plane, which looks like a failing DRAM to me. (Not suprising-- full load of Micron Technology 4264's on board. I can replace those easy enough.) The video display was "dark" which I decided was probably a failure in the 82S09 SRAM (a 64x9 SRAM, same as a 93419 for you trivia buffs). Replacing that brightened up the display. I might as well post my limited understanding of the I,Robot video section... There are two banks of DRAMs that look like they support an interlaced display. Assuming that the display is about 320x200 that's 64000 pixels, which fits nicely into 64K DRAMs. I think that six bits of each bank are used to supply the address to a color lookup table (the 82S09/93419). I *think* the 7th bit selects either the "polygon" or the "text" display plane (that's a guess though). The 9 bit output of the 82S09 is fed to a latch which in turn feeds a simple resistor based D/A to get the RGB outputs for the color. Each color has 2 bits that directly drive the color gun, there is then 3 bits which drive the overall intensity of the color. (So in effect you can have 64 "colors" with 8 intensities each. Works nicely for shading and depth-cueing, and is a very "Atari" way of doing things... ;-) Anyway, this is where I get a little baffled. My PCB doesn't like to display shades of white. (In self test the white-to-black bar is a bunch different colors instead of eight shades of white.) Since all the other colors are fine, I think the output section is fine. I suspect that the color lookup table isn't getting loaded properly. If this symptom sounds familiar to you (and you fixed it already!) please let me know! More trivia... It doesn't look like I,Robot needs that +15.5V from the PSU. The only place I could find it used was to bias the watchdog enable (like the older 10.3VDC unregulated did on the color vector games). Any pointers will be most welcome. Yet more trivia. My PCB is Serial number 00300, and the cabinet is Serial number 00361... -Clay ----------------- From: brown_du@eisner.decus.org (Duncan Brown) Subject: Re: I Robot question... Date: 1996/04/20 newsgroups: rec.games.video.arcade.collecting > Hopefully anyone out here with an I Robot can help me out on this. > > When I power up the game in normal mode (not test mode), the screen > continually says that "I've hit a black hole" or something like that > and gives me 5000 bonus points. I can't start a game or play one > normally, because the system just keeps displaying that message. > > Has anyone ever seen this behaviour or know what causes it?? Go into test mode. You will either see the message "Bad MBRom 1LM" or "Bad MBRom 1HJ". If it says 1LM, then the chip at 1HJ is bad; if it says 1HJ then the chip at 1LM is bad. THEY ALL GO BAD!!! They are masked ROMs and VLSI Tech must have been having a bad week at the old clean room or something.... If that isn't it, I'll be very surprised... Duncan, "Mr. I, Robot" ----------------- Newsgroups: rec.games.video.arcade.collecting Subject: Re: TECH: 4164 equiv RAM (I, Robot) From: tim@arcadecollecting.com Date: Wed, 16 Apr 2003 05:05:26 GMT I can't answer your specific question, but I can say that you can use 41256's instead. I have had them running in mine for 4 or 5 years without a problem. Tim John Knutson wrote: > I've been (slowly) trying to fix the infamous video memory problem > with my I, Robot. I purchased replacement RAM from a local > electronics shop, and have pulled all the old micron RAM and put the > new chips in sockets on the board. Unfortunately, it now looks far > worse than it ever was before. Currently, parts of the display flash > constantly, and the colors aren't always right (e.g. purple "I, Robot" > logo with yellow #1984). > > Visual inspection of my work hasn't turned up anything obvious. There > remains the possibility that the chips or sockets are bad, or I cut a > trace by accident. > > Before I start doing all kinds of testing to try and figure out what > the cause of the problem is, I wanted to make sure the RAMs were the > same. The original chips were micro MT4264-15s. The replacements I > bought were Fujitsu MB8264A-10s. These don't exactly match up in the > IC Master alternate source guide. The MT4264 *does* match the Fujitsu > MB8264 (no "A")... But the "A" version of that chip has a different > alternate than the MB8264/MT4264, even though they're all 64Kx1. > > Before I go any further (spending time or money), can someone confirm > that the MB8264A is or is not a valid substitute? Or, failing that, > give some insight as to what the cause of the current video problem > might be... ---------------------- From: clay@supra.com (Clay Cowgill) Subject: Re: I, Robot woes... Date: 1997/03/17 Newsgroups: rec.games.video.arcade.collecting Todd Bordelon wrote: > Problems and Questions: > > - Display has a series of brownish striped vertical lines that > sometimes move a pixel in either direction. Obviously a > ram problem. (Really badly interferes with game-play). > > Where's the video ram, and whats an equivalent replacement? The video ram are Micron 4164 equivalents. Any 64Kx1 type DRAM will work. That's not your problem though. DRAM failures will be horizontal "sparkles" in the video. The vertical stuff seems to be somewhat characteristic of I,Robot. You can clean it up considerably by running a bunch of *really* clean +5V and GND lines to *both* boards. > - I've hooked up no sound. The original power supply took care > of audio amplification. Has anyone else out there replaced > their power supply? If so, how'd you handle audio? I sent you e-mail on this, but for everyone else a $50 Clarion car audio amp will allow you to play I,Robot at painful volume levels. (Replace the wire-wound volume rheostat with an audio-taper pot from RatShack prior to the amplification stage.) > - The picture on the GO7 is condensed on the right hand side. > Any way to widen it over there? I've got about a 1-inch > vertical section over there that the picture ain't getting > to. Mine does that a little. I,Robot must have a long Hsync pulse or something. Anyway, you can greatly minimize it by adjusting the centering jumpers on the GO-7 board and then playing with the horizontal width coil. > One thing I forgot to mention: Occasionally in self test, > I get a BAD QP in the lower status window. Whats this? That's the Quad Pokey chip. (Sound) Mine does that every once in a while too. Probably just a matter of the CPU coming up before the QP is ready. I wouldn't worry about it unless it happens a lot. Atari had a bunch of various problems with chip propogation delays in their designs (using LS parts when plain TTL were needed for speed) so once in a while you'll get bit by a timing glitch on an Atari game. It's natural. -Clay ------------------------ From: clay@supra.com (Clay Cowgill) Subject: Re: I, Robot status and *Bug/Easter Egg* Date: 1997/05/14 Newsgroups: rec.games.video.arcade.collecting Todd Bordelon wrote: > The original video RAM was 15 nanoseconds. Hmmmm... > Looked at what I'd put in there: 12 nanoseconds. > Could it be??! I thanked myself for socketing all > of the ram, and proceeded to put new 15 nanosecond > chips in (well, they were from an XT I had a long > time ago). Powered it up... BAD flashing as well > as random garbage patterns every few seconds. -12's will be fine. If there's a problem with the VRAM you'll see it as a horizontal line of flickering dots. More likely you have a bad EPROM. I don't know the number, but there are two that always seem to go bad. If that doesn't help, look for the CLUT RAM-- it's an 82S09 or a 93419. About a 28pin critter-- on the Video board. You can rob a replacement off an MCR game or a Nintendo Donkey Kong era game. Give that a try... -Clay --------------------- From: rlboots@cedar-rapids.net (Rodger Boots) Subject: Re: I, Robot status and *Bug/Easter Egg* Date: 1997/05/16 Newsgroups: rec.games.video.arcade.collecting >The original video RAM was 15 nanoseconds. Hmmmm... >Looked at what I'd put in there: 12 nanoseconds. That's not 15 and 12 nanoseconds, it's 150 and 120 nanoseconds. Put the 120s in and you'll have a better chance at getting it to work. -----------------------