pcrock Posted September 9, 2020 Author Share Posted September 9, 2020 17 hours ago, ChildOfCv said: "Works" and "Correct" are not necessarily the same thing. From Fairchild's TTL design notes: Hi friend. Once more thanks for replying. I know and I understand you are right about the TTL information you told us so I'm going to change my answer. What I meant is that this cartridge has been running Atari games for the past 37 years without ever failing. Which means that for this purpose, at least, this circuit works correctly in the way it is designed even if it is a weird thing. I have another older PCB whose design is also like this with these floating pins. But now you advised us about the question, I found a lot of other circuits here that matches exactly as you sayd! It haves the pin 4 and 5 conected together ! Once more I hane no words to thank you all for helpping me here! Quote Link to comment Share on other sites More sharing options...
pcrock Posted September 9, 2020 Author Share Posted September 9, 2020 5 hours ago, alex_79 said: Another try... tapper_fa0_v3.bin 8 kB · 2 downloads Woooww! I will burn an Eprom just now to test it!!!! Thanks again!!! Quote Link to comment Share on other sites More sharing options...
Danjovic Posted September 10, 2020 Share Posted September 10, 2020 On 9/8/2020 at 7:04 PM, ChildOfCv said: Makes me wonder how this board ever worked I have seen that before, it is not uncommon for 70's / early 80's circuits. Depending upon the technology of fabrication of the chip, the emitters at input pins are biased enough to pull up the pin. one "advantage" of leaving the pin float was to save one pin in the fan-in/fan-out budget, and such mindset was problably very live in the head of the enginners that designed the board. I would not rely on that, though, for the same reasons you have exposed ?! 1 Quote Link to comment Share on other sites More sharing options...
pcrock Posted September 10, 2020 Author Share Posted September 10, 2020 (edited) 7 horas atrás, alex_79 disse: Outra tentativa ... tapper_fa0_v3.bin 8 kB · 3 downloads WOOOOOOOWW !!! alex_79 !!! O Tapper v3 que você me enviou hoje está funcionando MUITO BEM !!!!!!!!!!!!!!!!!!!! Sinto muito pelas fotos ruins, mas minha placa ATARI 2.6K está conectada a um dispositivo CRT !! Estou mandando as fotos !!! Muito obrigado aos amigos alex_79 e Thomas Jentzsch por me ajudarem na conversão de bankswitching para minha prancha brasileira !!! E obrigado a todos pela atenção em mim e nos meus problemas !!!!! Edited September 10, 2020 by pcrock Quote Link to comment Share on other sites More sharing options...
alex_79 Posted September 10, 2020 Share Posted September 10, 2020 (edited) I'm glad it finally worked! So it seems that the bankswitch on this board doesn't work reliably if the code that accesses the hotspot is being run from RAM. In the last version of "Tapper" it has been changed to run from ROM. Edited September 10, 2020 by alex_79 1 Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted September 10, 2020 Share Posted September 10, 2020 That's pretty odd. Any idea why this is happening? 1 Quote Link to comment Share on other sites More sharing options...
pcrock Posted September 10, 2020 Author Share Posted September 10, 2020 19 minutes ago, Thomas Jentzsch said: That's pretty odd. Any idea why this is happening? Just to report. I don't know if this has to do with the problem but on this circuit, pins 4 and 5 of the LS00 are soldered together. Quote Link to comment Share on other sites More sharing options...
alex_79 Posted September 11, 2020 Share Posted September 11, 2020 11 hours ago, Thomas Jentzsch said: That's pretty odd. Any idea why this is happening? I guess it's a timing issue: the address lines don't switch state all at the same time, and the logic gates themselves add delay to some of the signals too. When accessing the hotspot from RAM, A12 stays unset, and maybe during the transition of the remainig bits between the valid hotspot address and the valid next instruction one, a pattern corresponding to the other hotspot (or the "illegal" state of the latch) briefly appears on the bus, messing the bankswitch. This is just my naive theory, so don't take my word on it! I'm able to trace the circuit and reconstruct the truth table based on how the logic gates are wired, but understanding what happens during the transients is well beyond my skills. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted September 11, 2020 Share Posted September 11, 2020 Got you. The floating pin is not responsible for this, right? Quote Link to comment Share on other sites More sharing options...
alex_79 Posted September 11, 2020 Share Posted September 11, 2020 It doesn't change the truth table: in both cases (pin 4 floating or connected to pin 5) the gate acts as an inverter for the signal on pin 5. Whether it affects the timing during the transient, I have no idea. Quote Link to comment Share on other sites More sharing options...
pcrock Posted September 11, 2020 Author Share Posted September 11, 2020 1 hour ago, Thomas Jentzsch said: Got you. The floating pin is not responsible for this, right? As I told before, this is not the circuit with the floating pin. The board I test the roms haves the pins 4 and 5 connected together. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted September 11, 2020 Share Posted September 11, 2020 Sorry, must have missed that. 1 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted September 11, 2020 Share Posted September 11, 2020 (edited) 50 minutes ago, alex_79 said: It doesn't change the truth table: in both cases (pin 4 floating or connected to pin 5) the gate acts as an inverter for the signal on pin 5. Whether it affects the timing during the transient, I have no idea. I think the problem is that unless it's accessing ROM on the instruction following the bank switch, A5 and A6 will still "jiggle" the flip-flop until A10, A9, or A7 finally trickle through their path. A12 is literally the only way a cartridge knows it's being read. But for the bank switch scheme, it depends on NOT A12, meaning that it can only guess that the access is happening. Edit 2: Even A12 isn't good enough. The next instruction after a bank switch needs to be in an address range that has both A5 and A6 clear. So, xx0x, xx1x, xx8x, or xx9x. This will keep A5 and A6 low until A12, A10, A9, or A7 can finish shutting down the bank switch select logic. I think if you want a reliable flip-flop, you need a circuit that bases the toggle on an edge trigger instead of this level-triggered crap. Edited September 11, 2020 by ChildOfCv 2 Quote Link to comment Share on other sites More sharing options...
alex_79 Posted September 11, 2020 Share Posted September 11, 2020 3 hours ago, ChildOfCv said: The next instruction after a bank switch needs to be in an address range that has both A5 and A6 clear. So, xx0x, xx1x, xx8x, or xx9x. This will keep A5 and A6 low until A12, A10, A9, or A7 can finish shutting down the bank switch select logic. Weird. In the Tapper rom that seems to work fine on this board, the next instruction is at $fff9, so both A6 and A5 are HIGH. I didn't include it in the schematic (as my goal was just to determine the truth table), but in the pics there's a small ceramic capacitor (unknown value) between pins 10-11 of the 74LS00 and GND. Could a cap placed there help filtering out transient variation of the /R and /S inputs due to A5 and A6? And, if so, could it be that it works when A12 pulses LOW, but it's not enough when A12 is steady LOW because the effect of the other signals (A9,A10,A7) are delayed by the extra gate (of the 74LS10) they go through compared to A12? Sorry for the likely dumb questions. As I've said I only have very basic knowledge about this stuff, but I find it very interesting nonetheless. 2 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted September 11, 2020 Share Posted September 11, 2020 2 hours ago, alex_79 said: Weird. In the Tapper rom that seems to work fine on this board, the next instruction is at $fff9, so both A6 and A5 are HIGH. Hmmm. It may be the capacitance of the outputs that keeps it alive long enough for A12 to disable it then. But for best reliability, I'd place the bank switch where A5 and A6 are both 0 instead of 1. 2 hours ago, alex_79 said: I didn't include it in the schematic (as my goal was just to determine the truth table), but in the pics there's a small ceramic capacitor (unknown value) between pins 10-11 of the 74LS00 and GND. This may interfere with state changes somewhat, but I bet its main purpose is to make sure the power-on state of the bank switch is always 0. 2 1 Quote Link to comment Share on other sites More sharing options...
pcrock Posted September 18, 2020 Author Share Posted September 18, 2020 On 9/11/2020 at 9:30 AM, alex_79 said: Weird. In the Tapper rom that seems to work fine on this board, the next instruction is at $fff9, so both A6 and A5 are HIGH. I didn't include it in the schematic (as my goal was just to determine the truth table), but in the pics there's a small ceramic capacitor (unknown value) between pins 10-11 of the 74LS00 and GND. Could a cap placed there help filtering out transient variation of the /R and /S inputs due to A5 and A6? And, if so, could it be that it works when A12 pulses LOW, but it's not enough when A12 is steady LOW because the effect of the other signals (A9,A10,A7) are delayed by the extra gate (of the 74LS10) they go through compared to A12? Sorry for the likely dumb questions. As I've said I only have very basic knowledge about this stuff, but I find it very interesting nonetheless. Today I made a discovery! I found out that of all these converted roms, centipede doesn't work on one of my consoles!! All roms converted by friend alex_79, work on 2 consoles that I have that use TIA C010444 (and also on another one that uses UM6526N) but the Centipede does not work on the console that I have that uses TIA UM6526N. All other roms work on all three consoles. That is no matter to me, I plan to change TIA UM6526 to KSC131 or C010444 but is a curious thing. I also found that the original ThunderGround (By Sega) (4K) game doesn't work on this console either. When I start, all lives die instantly one after the other and the game is over. Hundreds of other cartridges that I have work normally on this console. Quote Link to comment Share on other sites More sharing options...
spadovan Posted March 21, 2022 Share Posted March 21, 2022 On 9/6/2020 at 4:49 PM, pcrock said: I had a cartridge like that when I was a kid. It had BeamRaider, Tapper, Galaxian and Pengo and was my favorite cart but when I was 17 years old, I gave it to a friend! He promissed to return it to me when I asked for it back. eu fiz um hack do logo no jogo beamrider para você. i made a logo hack in beamrider game for you. On 9/6/2020 at 4:49 PM, pcrock said: I really regretted it cause he says that lost my cart and I really want to play these games again with my daughter. Here in Brazil, unfortunately any cartridge (even a pirate) that has this game (BeamRaider) is very expensive !! Estou anexando mais jogos de um cartucho de 16 jogos que o alex_79 me ajudou a fazer o dump. I'm attaching more games from a 16 game cartridge that Alex_79 helped me dump. Beamrider - Mania - UA.bin 16 jogos bank UA.zip 1 Quote Link to comment Share on other sites More sharing options...
pcrock Posted April 3, 2022 Author Share Posted April 3, 2022 On 3/20/2022 at 11:52 PM, spadovan said: eu fiz um hack do logo no jogo beamrider para você. i made a logo hack in beamrider game for you. Estou anexando mais jogos de um cartucho de 16 jogos que o alex_79 me ajudou a fazer o dump. I'm attaching more games from a 16 game cartridge that Alex_79 helped me dump. Beamrider - Mania - UA.bin 8 kB · 2 downloads 16 jogos bank UA.zip 90.93 kB · 3 downloads Wooooow Very very very cool !!! I will burn an eprom just now and play it with my Kids!!!! Very very Thanks!!!!!!!! 1 Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted April 3, 2022 Share Posted April 3, 2022 (edited) On 3/21/2022 at 3:52 AM, spadovan said: I'm attaching more games from a 16 game cartridge that Alex_79 helped me dump. Subterranea is labelled NW, I suppose that means "Non Working". Actually it works 50% with WIP Stella (startup bank has to be randomized in Developer settings). For details look here. Edited April 3, 2022 by Thomas Jentzsch 1 Quote Link to comment Share on other sites More sharing options...
pcrock Posted August 29, 2022 Author Share Posted August 29, 2022 On 3/20/2022 at 11:52 PM, spadovan said: eu fiz um hack do logo no jogo beamrider para você. i made a logo hack in beamrider game for you. Estou anexando mais jogos de um cartucho de 16 jogos que o alex_79 me ajudou a fazer o dump. I'm attaching more games from a 16 game cartridge that Alex_79 helped me dump. Beamrider - Mania - UA.bin 8 kB · 14 downloads 16 jogos bank UA.zip 90.93 kB · 15 downloads Já fiz o cartucho e já estou usando!!! Ficou perfeito! Não tenho palavras pra agradecer!!! Você é Brasileiro?? I just burned an EPROM and it works great!!!! I have no words to thank you! Are you Brazilian? 1 Quote Link to comment Share on other sites More sharing options...
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