F18a issues with certain games

[omf]

today my vga to hdmi converter arrived i ordered from ebay so i decided to plug everything together and do some games playing

i had already installed the f18a the other week and know that it works fine because i have played games using it briefly to test it

 

the games i attempted tonight that a[[eared to cause issues are the following:

 

pong from the pong / computer space box set, this game does nothing at all. i know the game works because it works fine on the same machine using the vdp chip and still works on my French board

the re release of moon patrol, this game works however it crashes in about 2 seconds once the game has started (in my case beginner mode)

 

the issue occurs if the vga to hdmi box is connected or not

 

can anyone confirm this or know what could be the issue? could changing the f18a jumpers offer a fix?

 

anyone have any ideas?

 

[TPR]

All three games worked just fine for me on my F18A system. I tested the actual carts for each game.

 

[omf]

All three games worked just fine for me on my F18A system. I tested the actual carts for each game.

 

IMG_9962.JPG

IMG_9961.JPG

IMG_9957.JPG

IMG_9958.JPG

IMG_9954.JPG

IMG_9956.JPG

i suppose it may be a ntsc / pal issue, my machine is pal obviously

 

ill email Matthew Hagerty he should have a better idea as he created the thing

[omf]

tried the actual cartridge of pong and the downloaded rom on the ultimate SD, it still didn't work on either

[matthew180]

AFAIK the NTSC and PAL ColecoVisions are the same other than the 9928 vs 9929 VDP and associated video output circuitry. Does anyone know if there any other differences between the NTSC and PAL CVs?

Changing the F18A jumpers probably won't change things, other than making your system not work in some cases.

   --    USR           On    Off
   -- -------------------------
   --  1 Sprite dflt|  32  | 4
   --  2 Scan lines |  No  | Yes
   --  3 CPUCLK pin | P38  | P37
   --  4 CPUCLK en  | HI-Z | CPUCLK

   -- USR3 CPUCLK pin.  Provides support for the 9128/9129 that output CPUCLK on pin37.
   -- USR3 and USR4 - CPUCLK pin and CPUCLK Enable.
   --        _________
   -- RAS  =|1   U  40|= XTAL1   9918A    9928A/29A 9118    9128/29 F18A
   -- CAS  =|2      39|= XTAL2   ======== ========= ======= ======= ====
   -- AD7  =|3      38|= ....... CPUCLK   R-Y       CPUCLK  R-Y     HI-Z / CPUCLK
   -- AD6  =|4      37|= ....... GROMCLK  GROMCLK   NC      CPUCLK  GROMCLK / CPUCLK
   -- AD5  =|5      36|= ....... COMVID   Y         COMVID  Y       NC
   -- AD4  =|6      35|= ....... EXTVDP   B-Y       EXTVDP  B-Y     NC
   --

   -- Basically:
   --             USR3 USR4
   -- TI-99/4A     on   on    -- The 99/4A does not use the CPUCLK, but this is NOT the default of the 9918A
   -- 9928/29      on   on    -- CPUCLK on pin38 disabled so it does not cram 3.5MHz into the R-Y circuit
   -- 9918A/9118   on  off    -- CPUCLK output, GROMCLK output (pin37 is not connected on the 9118)
   -- 9128/29     off   on    -- CPUCLK on pin37 disabled, CPUCLK output on pin38 enabled
   -- not used    off  off    -- CPUCLK output on both pin37 and pin38

You really don't want to take USR3 or USR4 off unless you know for sure that your system needs the CPUCLK output on pin-37 or pin-38.

 

I'm not sure what could be causing the problem. It would be nice to know if any other PAL CVs have the same problems. I don't have access to my own CV right now, but during testing I did discover that one of my controller ports was bad and was only exposed when trying certain games. It took me a long time to discover that problem, after much frustration. However, TPR has verified the games do work with an F18A so it appears to be something else.

 

Do you have access to another CV that you can try? I'm assuming you had to remove the original VDP and install a socket, so you might also verify the solder joints.

[+grips03]

I've been using my F18a on my NTSC console for 2-3 years and only had one bug with it. It was with Battle of Hoth game. F18a sometimes made ATAT head look funny. Besides that all other games have worked great.

[omf]

wouldn't the timing crystal be different for the NTSC machines due to increased refresh rate?

[+nanochess]

wouldn't the timing crystal be different for the NTSC machines due to increased refresh rate?

As far as I know every Colecovision runs at 3.579545 mhz, only changes the frame rate on the VDP side.

 

I think that probably your RAM chips are bad, or your Z80, it can happen over time that small electrostatic discharges damage chips or simply the internal oxydization is very advanced.

[omf]

AFAIK the NTSC and PAL ColecoVisions are the same other than the 9928 vs 9929 VDP and associated video output circuitry. Does anyone know if there any other differences between the NTSC and PAL CVs?

 

Changing the F18A jumpers probably won't change things, other than making your system not work in some cases.

You really don't want to take USR3 or USR4 off unless you know for sure that your system needs the CPUCLK output on pin-37 or pin-38.

 

I'm not sure what could be causing the problem. It would be nice to know if any other PAL CVs have the same problems. I don't have access to my own CV right now, but during testing I did discover that one of my controller ports was bad and was only exposed when trying certain games. It took me a long time to discover that problem, after much frustration. However, TPR has verified the games do work with an F18A so it appears to be something else.

 

Do you have access to another CV that you can try? I'm assuming you had to remove the original VDP and install a socket, so you might also verify the solder joints.

i have tried the F18a on my pal colecovision and a French RGB board, both machines produce the same problem

 

i have replaced both sockets on both machines with sockets, i think the solder points should be good as i wouldn't have messed up two boards, I have done a lot of soldering so i am quite experienced and the games work properly if the f18a is removed and the VDP chip is inserted into the VDP socket

 

i have swapped the Z80 between the French and pal machine during fault finding with the French board, however they do both work. I guess i could socket it and look for a replacement on ebay just to be sure

 

i also have a nice new alternate power supply on the way from Germany, ill try that as well just in case, the voltages look fine though when measured

with a meter

[youki]

French RGB Board are SECAM. I don't think it makes a difference for F18a. But just in case.

[omf]

doesn't the French RGB machine output normal RGB and not region specific SECAM? that's what I understood, using the f18a on it bypasses all that lot any way does it not as its a video circuit replacement ?

 

the new parts haven't arrived yet so i have nothing to test right now

[matthew180]

The F18A does not use the XTAL inputs on pins 39 and 40, it has its own on-board oscillator so any video circuit differences between the various consoles would not matter. Just so I'm clear, other games do work in this system, yes? The problem is only with the Pong and Moon Patrol games?

 

Also, the CV does have a fast power-on reset and these games might be trying to hit the F18A before it is configured. Have you tried powering on the games then hitting the reset button? Luckily the CV's reset is a real hardware reset and the F18A is already powered-up and configured, so that usually fixes any startup problems. Alternatively you can install a larger capacitor in the RC time constant circuit to slow the CV to about 150ms or so and see if that helps.

[omf]

The F18A does not use the XTAL inputs on pins 39 and 40, it has its own on-board oscillator so any video circuit differences between the various consoles would not matter. Just so I'm clear, other games do work in this system, yes? The problem is only with the Pong and Moon Patrol games?

 

Also, the CV does have a fast power-on reset and these games might be trying to hit the F18A before it is configured. Have you tried powering on the games then hitting the reset button? Luckily the CV's reset is a real hardware reset and the F18A is already powered-up and configured, so that usually fixes any startup problems. Alternatively you can install a larger capacitor in the RC time constant circuit to slow the CV to about 150ms or so and see if that helps.

i tried strip poker last night and that failed to work also.

 

i have tried other older games and they (or the ones i tried) seem to work donkey kong, boulder dash, frogger, the original moon patrol all work fine

 

i have tried reset after waiting for a short time so everything is powered, but their are no signes of resetting has occurred on screen anyway

i am going to try later tapping into the audio and using strip poker later which starts playing audio straight away to see if the while machine has died or whether its just t the video output

 

i also tried bending out the pins of the f18a bard slightly so they pushed on the socket a bit harder as i thought there was possibly bad contact on one pin, this did not do anything however.

 

i also tried starting the console without a cartridge which brings up the coleco no cartridge screen then plugged in a troublesome cartridge while the power is still on then pressing reset but it resets to a blank screen like what happens when you turn on with that cartridge inserted

 

ill look into the timing capacitor, but as there are no schematics for the PAL consoles it could be a bit hit and miss. the capacitors around the crystals i guess

[matthew180]

This seems very strange for sure. Do you have an MSX1, 99/4A, or some other 9918A/9928/29 based computer that you can use to verify your F18A?

 

Also, do you have a photo of the exact CPU and VDP of the troubled system that you could post? I'm wondering if your CV is using some different variation or version of either IC. When I was prototyping the F18A, interfacing the Z80's interrupt input gave me some problems. The solution ended up being rather simple (a 100-ohm resistor to impedance-match the signal), but I'm wondering if there are other Z80 variations out there that exhibit different characteristics.

[TPR]

My copy of Strip Poker worked just fine. Sounds like it's got to be some issue with your system and not the F18A.

[omf]

This seems very strange for sure. Do you have an MSX1, 99/4A, or some other 9918A/9928/29 based computer that you can use to verify your F18A?

 

Also, do you have a photo of the exact CPU and VDP of the troubled system that you could post? I'm wondering if your CV is using some different variation or version of either IC. When I was prototyping the F18A, interfacing the Z80's interrupt input gave me some problems. The solution ended up being rather simple (a 100-ohm resistor to impedance-match the signal), but I'm wondering if there are other Z80 variations out there that exhibit different characteristics.

the vdp's in the picture both work, the top one is brand new and i have not attached a heat sink to it as yet to use it for any length, it plays troublesome games though, the second one had a heatsink on it but it came off

 

i have one other but i didn't bother to take a picture because the heat sink is still attached, but that plays the troublesome games also

 

the first cpu image (with the proper cartridge in it (in this case strip poker) is on the pal composite modded machine

the second cpu image with a bare cartridge board (in this case boulder dash DIY cart) is the French RGB machine.

 

all the vdp's work in both consoles and allow all the games to work.

 

just when the f18a is plugged in it doesn't like some games (which is looking like the newer releases)

 

green screen is when attempting to play pong and strip poker

 

blue selection screen is donkey kong

 

boulder dash is self explanatory

 

pictures taken on the pal machine with f28a attached

[omf]

oh also, during the green screen i put headphones directly on the sound output line of the audio chip, and it was silent so looks like the machine has completely crashed, doing the same when boulder dash was on the boulder dash music can be heard

[omf]

My copy of Strip Poker worked just fine. Sounds like it's got to be some issue with your system and not the F18A.

humm, my strip poker cartridge doesn't look like that

 

oh well!!!

[omf]

Just hooked up the replacement power supply i bought, i can confirm that this issue isn't power related as it still happens on the new power supply

[Kiwi]

PONG uses screen mode 2 text (3 char tables, 1 color table setting). Strip poker is using screen mode 2 bitmap. I'm not 100% sure if Donkey Kong uses the default screen mode 0, seems like it works with screen mode 0. Boulder Dash seems to be screen mode 0. It seems that the chip having trouble setting the registers to graphic mode 2 get the game to display correctly.

[omf]

PONG uses screen mode 2 text (3 char tables, 1 color table setting). Strip poker is using screen mode 2 bitmap. I'm not 100% sure if Donkey Kong uses the default screen mode 0, seems like it works with screen mode 0. Boulder Dash seems to be screen mode 0. It seems that the chip having trouble setting the registers to graphic mode 2 get the game to display correctly.

Is this on the colecovision board or the f18a?

i could possibly change whatever chip does this and see what happens??

[Tursi]

Graphics mode 2 has been heavily tested on the F18A using a lot of different masking modes, I don't think that's the issue. Combined with the fact that all the titles work for TPR it seems more like a local issue. Or at least we need a tie-breaker.

[omf]

Graphics mode 2 has been heavily tested on the F18A using a lot of different masking modes, I don't think that's the issue. Combined with the fact that all the titles work for TPR it seems more like a local issue. Or at least we need a tie-breaker.

well the only difference that i can think of is that mine are European machines where as TPR's is a USA machine

i dont think there is anything majorly different with the two apart from the video circuitry but something is causing this and its not my machine as such as i have tested it on two. a PAL and French RGB machine, i would have expected at least one to work,

 

I will get to test it on another at some point as i will be installing the f18a in a friends machine for him at some point, his is also a European or French RGB machine ( he has several) the choice is up to him which one he wants to convert to f18a, although im guessing the standard PAL machine as his RGB one gives out a good picture, unlike mine which has smudgy vertical lines (which doesn't appear to be a VDP problem as i have changed the VDP chip. going to try the transistors next and see if they are problematic....

[omf]

i was thinking, probably doest affect it but i have performed a composite video mod which requires component removal, see the PAL section of this guide, this is the mod i have done. would this affect the f18a in certain games?

http://www.coolretroprojects.com/ColecoVision_AV_Mod_Installation_Guide.pdf

[matthew180]

I'm still trying to collect some information, but here is something to try in the meantime. Over in the 99/4A group several people have been building their own computers from chips and they are using the F18A. They were having some stability issues and found that they needed to add small capacitors between ground and the /CSW, /CSR, and MODE pins. In one system they only added a capacitor to the MODE pin, in another it was /CSW and /CSR. The values they were using are in the 4.7pf to 120fp.

 

I'm not sure why this would be necessary, the F18A uses a 245 buffer for these inputs. However, mixing IC logic families can always be problematic and it could be something with the specific 245 (MC74LCX16245) buffer I'm using (although I tried really hard to pick one that was designed to work with the ICs used in the home computers of the era.)