unebonnevie

So, I digged out the factory 64KB coco2 *with* extended BASIC, it reports 24817 via the "? MEM" BASIC command. Pretty strange. I think it has to do with the fact that my 16KB Coco2 does not have extended BASIC ROM installed?

I found the below link/discussion. http://www.coco3.com/community/2010/06/possibly-very-naive-questions/ One entry is: "Most 16K CoCo 2’s had socketed RAM to facilitate upgrading to 64K. The 16K RAM in the CoCo 2’s were also 5V only chips (in contrast to the 4116’s of the earlier machines). 64K CoCo 2’s, at least the later ones, had soldered in RAM – no upgrade was anticipated since it already had 64K. There are always exceptions I suppose – I’ve seen some CoCo 2’s that were upgraded to 64K using a memory board like the CoCo 3 upgrade. The CoCo 3 RAM is probably good – BASIC, in order to retain backwards compatibility only uses 32K. Software such as Big BASIC and 512K BASIC allowed BASIC to use more RAM. "

Hi, I just got from eBay and old 16KB Coco2 computer. I got eight 4164 (64Kb x 1, which is 8KB) DRAM chips (single 5V voltage) to replace the eight 16Kb x 1 (2KB) chips. I followed the below instructions found on the net. My Coco2's model is 26-3134. To upgrade the 26-3134 or 26-3136 to 64 KB of RAM, it is necessary to replace the eight 8040517 chips with 4164 chips of 200 ns or better access time, and to solder a wire between the two pads labeled J1. J1 is located next to IC7. Things boots up after the upgrade, per the above instructions. I type in "? mem" from BASIC to check the memory size, and the 31015 number is printed out. It certainly bigger than roughly 14KB reported with the original 16KB my Coco2 comes with. But, I thought it would be bigger with 64KB RAM upgraded, no? Thoughts? Thanks!

Hi, I am bit confused of the max size 16KB/32KB/64KB a ROM cartridge can have for the Coco2. I read in the Coco2's technical reference manual that it can take 16KB/32KB/64KB ROM. But when the cartridge is selected via the /CTS signal of the cartridge port, the ROM address covers from 0xC000 to 0xFF00, according to the Coco2's memory map. How would I ensure that if I have a cartridge of 32KB/64KB ROM size all my code will be running not just the first 16KB? My Coco2 has 64KB. So, I guess the cartridge ROM size depends on the RAM size of your coco2? Thanks!

Found the schematic. http://www.grandideastudio.com/wp-content/uploads/pp_atari5200_schematic.pdf

Hi, I have seen the 5200's schematics of wiring two 16KB ROMs for the cartridge. Just wondering if possible just to use a single 32KB ROM. Thanks!

Hi, Today I found out that the LucasFilm's Ballblazer game cartridge has a pokey chip it in? Would like to see the cartridge's schematics. Thanks,

Hi, I would like to construct a cartridge board so that I can press a button to reset the 5200. Is that possible? (I realize that I can hook up a button to the 6502C's /RESET pin, but I am not looking that route.) I read the below from http://www.atarimuseum.com/videogames/consoles/5200/conv_to_5200.html, but I am kind of not getting it. So, I put a digital 1 (5V) on the two interlock pins to do a reset system and digital 0 (0V) is not to reset the system? The cartridge ROM can be 32K bytes long and resides in memory from $4000 to $BFFF. Figure 4 shows the pinout of the cartridge slot. The two interlock connectors are wired together on a cartridge board. The 5200 uses this as a switch for the cartridge's power connections and as a Reset signal. Therefore, a cartridge may be safely removed or inserted while the 5200 is powered on. D0 1 36 Interlock D1 2 35 A11 D2 3 34 A12 D3 4 33 A10 D4 5 32 A13 D5 6 31 A9 D6 7 30 Audio In (2 port) D7 8 29 A8 Enable 80-8F 9 28 Not Connected Enable 40-7F 10 27 A7 Not Connected 11 26 +5V DC Ground 12 25 Ground Ground 13 24 Ground (Video In on 2 port) Ground (System Clock 02 on 2 port) 14 23 Ground A6 15 22 A4 A5 16 21 A3 A2 17 20 A1 Interlock 18 19 A0 Thanks!

Hi, I read that the Atari 5200 2-port version has additional address lines for the cartridge. Is there documentation on the differences in address lines for the 4 and 2 ports? Thanks!

Ah, there is a programming forum for the Atari 5200, Atari systems -> Atari 8-bit computers -> Atari 5200/8-bit programming. It has the below post. http://atariage.com/forums/topic/255139-action-bank-selection/?hl=%2Bbank+%2Bswitching&do=findComment&comment=3561345

Pardon if this an FAQ. But would appreciate pointers or sample code. Thanks!

Damned! I could kick myself in the butt for this! Yes, the brightness was turned up too far! It's OK now. I should have checked the obvious before doing surgery on my Vectrex. Well, I guess now I have a real problem to fix -- the volume potentiometer, which is tied to the power switch. Need to look of the ohm rating for the volume potentiometer and replace it. Thanks!

Hi, My vectrex has a display problem -- really bright dot in the center and rays are drawn everywhere. I discharged the monitor properly and attempted to re-sit all the chips that are socketed. I checked all caps of the main board and the side board, and none is bulging. (Damned! In the process of taking the board out for cleaning, I broke the potentiometer that control the volume. Anyway, that's the least of my problem now.) Any idea what's wrong with the monitor or certain chips? Thanks!

Awesome! Thank you!

Hi all, Format wise, i.e., load address, what are the differences between *.car (cartridge) and *.rom files. I would like to know how the Atari 8-bit computers recognize these files. Thanks!

Hi, I am trying to make a dev board for the Atari 5200. I have an extra Pac Man cartridge and would like to know to open it safely. There is a screw in the middle of the back side of the cartridge, but taking the screw out does not seem to losen the casing. Thanks for any tips.

Hi, My Atari 5200 (still using the RF modulator) has scrambled display along the right side edge. Something like what you see in the YouTube video https://www.youtube.com/watch?v=zLgEogvPLzs. Is there a way to fix this? Would a composite mod help? Thank you!

Hi, I just got an Atari 7800 from eBay, and, as usual, it does not come with the power adapter, which has an insane strange connector. So, I am going to do a power mod. I have a 9V DC and 1A output adapter, as stated on the power adapter's label. When I measure the voltage output, it's always 12.47V. Pretty strange. So, I was looking at the Atari 7800's schematic but can't find if it has some sort of voltage regulator (like the 7805 voltage regulator) to ensure 5V is what all the chips on the motherboard get, even with 9-12V input. So, is 12V to high, even the adapter says it has a 9V output. By the way, why does the power adapter has higher output than it claims? Thanks!

SO, the RED wire goes to the shorter (inside) connector, the positive lead, of the power jack? And the BLACK wire (GND wire) goes to outer connector, the negative lead, of the power jack? Thanks!

Also, mostly to confirm. Is the Atari 5200 AC power adapter negative center or positive center? Thank you!

Yes, on the cartridge, the contact part into the edge connector of the Atari 5200 has signal/copper pads, the address lines, the data lines, etc. (I use Eaglecad too much that I call those connections as pads on the cartridge board.)

Thanks!

Hi, I found Atari 2600 and 7800 EagleCad library parts, but not Atari 5200 anywhere. Thanks for any tip.

Yes, I am talking about the AC adapter. Thank you very much for the confirmation.

Hi, I just got a 4-port Atari 5200 off eBay. The seller bundled with a two-port system power supply rather than the proprietary one from Atari. I didn't know about this two-port and four-port versions of the Atari 5200 until today. Is there an alternative power supply solution (without acquiring specially made one by Atari) for the 4-port version of the Atari 5200? Thanks!