Geoff Oltmans

I suspected that might be the case. It seemed unlikely that it would be able to decode the base address correctly but then munge it up in such a way. i presume that others are able to use the finalgrom with disk controllers…

I’ll have to check continuity on the pins, but this cable has a molded on end. i do have the issue too remember where Alpiner doesn’t work with a speech synthesizer but does without.

I can get all of the outputs on the latch to change states.

I was able to revive mine with just a pencil eraser. I'm sure that works only so long though. ha.

...but then again it seems expansion memory isn't impacted in either low or high banks.

I suppose I should poke around on the expansion bus connector next with my scope and see if those signals look good and squared off.

Hey guys... I've been working to repair my TI setup... mainly I was focused on getting the disk controller to work. I was thinking that the issue was with the disk controller itself, but now I've turned my attention to the console itself. I've experienced a number of strange behaviors, and just recently as of yesterday received a FinalGROM99 to aid in debugging. Before receiving the cart, I was kinda focused on the disk controller like I said.... When attempting to do any disk access the system hangs. Before I had the cartridge I was testing this with TI BASIC, Disk Manager 2, and Personal Report Generator, just to see if I could attempt to read/write to the disk. The disk drive activity LED wouldn't light and motor wouldn't spin but apparently enough of the DSR could be accessed so that the system knew about the DSKx devices, and the disk controller activity LED would light when attempting to access. Using the Final GROM cart with Mini Memory, I started probing around the CRU write addresses to see if I could manually get the drive activity light and motor to turn on, and I can with it...however the CRU addresses I'm using seem like they are off (but that could be a result of my unfamiliarity with the 9900). I would expect that writing a '1' to address >1101 would turn on the motor, but instead a write to >1102 does. I'm testing using an oscilloscope. Basically everything works on subsequent even numbered addresses: >1100 - Activity LED/card select >1101 - nada >1102 - KACLK - Motor ON strobe >1103 - nada >1104 - HLT >1105 - zilch >1106 - DSEL1 >1107 - you guessed it >1108 - DSEL2 >1109 - "" >110A - DSEL3 >110B - SIDSEL These clearly wiggle with writing '1's and '0's, so the latch at U23 is good and doing it's job. I'm a little confused why the addressing is working out like this based on a read of the schematic. I would think that these should all have no gaps from 1100-1107. But, I know CRU addresses are effectively shifted by 1 on the address bus, so maybe this is how things work in the Mini Memory program? Dunno. Likewise if the DSEL1 and KACLK are both set, the disk activity light comes on and the motor comes on, so that circuitry works too. Before getting the Final GROM, I suspected that ROM access to the second ROM wasn't working, since the system would read the DSR linked list seemingly correctly, but hang on access (some of those routines are in the upper bank), just a working theory. But... with the FinalGROM inserted, the DSR access is completely jacked up. The system doesn't know anything about the controller, and inspecting memory in the DSR space from >4000->5FFF shows a bunch of garbage in it. So, the DSR linked list at the beginning isn't read right, TI BASIC et al doesn't know about DSK, and errors out without trying, no disk controller activity LED at all when attempting 'OLD DSK1.TEST" for example. The disk activity light at powerup doesn't flash nearly as long as it does with the Final GROM removed from the system. Tests to my expansion RAM in the PEB all seems to work fine with a diagnostic program (the CorComp one) and random reads/writes in the expansion memory spaces via Mini Memory. (above tests were performed without the RAM expansion or anything else in the PEB except the Disk Controller), so I think the flex cable interface is good. I also checked power supplies in the PEB and they are good. Now, onto the console itself.. With just the console and no PEB, I have noticed that video is a little flakey, but not flakey from the standpoint of bad ram. IF the display is really white (as in starting out a game of Hunt the Wumpus), the screen gets a bit squirrely and noisy... like the video amplifiers power supplies are noisy or sagging. Alpiner will play with no speech synthesizer, when music is playing some of the sound must be bleeding into the video as the video gets a bunch of wavy lines in it while sound is playing. The game won't play with the speech synthesizer installed past the game selection screen. As soon as the climber appears, it craps out. An actual Parsec cartridge will play with speech. So, That lead me to inspect the power rails on the console. I think those are good... a little bit of periodic noise 50mV p-p. So now I'm leaning toward caps on the main board. Any one experience issues like this?

I'm a little late to this party, just having reacquired a 99/4A system (it was my first "real" computer growing up), I think you hit the nail on the head on a number of problems. I think design decision wise it's pretty astounding how much money they designed into the system relative to its peers. The casework for the 99/4A couldn't have been cheap for one, and two the PEB chassis is equally spendy for not much benefit. Seems to me that they could have designed a whole combination 32K ram expansion, serial/parallel interface, and disk controller for about the same money they'd have had tied up in the PEB costwise. But, I love the system all the same, quirks and all as you say.

I am about 90% sure that Atari would have found a way to screw that up too.

You put this better than I possibly could ever... I owned all of Atari's consoles (save for Lynx) ex post facto, but I owned the NES contemporaneously and my own personal experience echoes your explanation. I had about a dozen games for my NES, and not a single one of them were third party titles, but all of them (including the early black box games) were extremely popular titles. Nintendo just had some damn fine games, and those are what people wanted. I also remember waiting in line to play Super Mario Bros in the arcade game before ever getting an NES, and I think that had a lot to do with its success. Back to the original topic, I have wondered if the reason that Atari did the XEGS in the first place was that they had a massive inventory of chips to unload and the XEGS was a way to do it.

Nevermind... answered my own question. lol

Are there any 7800 emulators out there with interactive debuggers? That would probably be beneficial. I need to try and reassemble the code to make sure that my disassembled image still runs.

Heh... this is my first foray into Atari 7800, so it's slow going. I've been trying off and on to identify the start of all the various graphics data. I've seen several places where the palette is changed as well as reading the switch states. I've studied over the Ms. Pac Man sources before so I have some idea of what I'm looking for.

I know this is a somewhat dumb game.... but I don't care, I like it! It's mindless, sure, and I can't figure out what office/factory/warehouse would have tubes that people would use to get to different floors instead of stairs or an elevator, but whatever. It's fun! Who else likes this odd game?

I've started disassembling the code on the game the other day. I'll see what I can figure out on it.

Heh, if you're looking for accurate color you're using the wrong system here! Colors drift over time after powering the system on.

Just got my Concerto today. Just tried it on my early unit and no dice. Mine's an AT84 unit. I've tried a handful of 7800 games other than that and they all appeared to be working correctly. Also tried a couple 2600 games and they were good too. The only issue I've run into apart from the above is while navigating the list of games it has locked up to a black screen which requires powering the unit off and on again.

Hmm... interesting. I've got a Concerto coming now, and I've been wanting to tinker with the 7800 so this might be a fun project.

Very nice!

I ordered something from a place in Oregon on November 29th with 2 day priority mail shipping. It was marked shipped and a tracking number showed it was delivered to the local post office on the 30th. The last update I've had on it was December 14th, where it was in Memphis. Memphis is about a 3 hour drive away from me and it still hasn't gotten here and no further updates on it.

yup... I'm holding out hope!

I like both Tower Toppler and Planet Smashers. PPII I think is a pretty decent little game. I don't have much experience with the other titles on the list.

Better to ask this question in the Atari 2600 subforum since that's a 2600 clone.

It's like the Drudge Report of Atari sales.

I have a couple right now.... A GE Portacolor 9" TV from 1983 that is currently busted. Currently trying to get this one fixed. A cheapy GE 13" RF-only TV from 1993 that I picked up from the side of the road the other day in working condition. Other than that, a Commodore 1080 with a cheapy RCA VCR to demodulate the RF signal. I'm going to get rid of one of the GEs. The Portacolor I feel is more period-correct for my Coleco/Atari/Commodore habit, but the '93 set is a better set for the most part. Apart from the immediate problem on the Portacolor (at least a shorted rectifier diode on the AC input), it has some problems with the picture being washed out/too bright on the left 1/3 of the screen. I think it has some value these days, so I'm putting a little bit of effort into resurrecting it.