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About eslapion

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  1. I don't know of any legacy DRAM which has 8 bits. I use a pair of logic ICs to perform demultiplexing and I use a single static RAM IC. It consumes about 3 mA of 5V only. In the past I thought of using a pair of 4416 (16k x 4) DRAM but even these have vanished.
  2. One of the various solutions I have considered is the use of TI's LMH1251 converter IC. During my research, I have found a document from TI which tells how to convert the output of a TMS99x8 to RGB but the conversion equations seemed almost identical to those used in any modern display equipment having component inputs. It also includes a DC level resetter which uses the old 4066 logic IC probably to address what you mention here.
  3. Hi everyone, I am Eslapion and I have been doing electronic things for the Commodore VIC-20 and 64 since 2006. However, I am also fascinated by the Colecovision and consider the possibility of making small electronic modules for this machine. Recently, I have started offering modules for the C64 and C128 which replace the DRAM with a single static RAM IC and consumes very little power and is much more resilient to problematic power supplies. I have noticed the Colecovision uses 16k x1 DRAM ICs (4116) which require 3 different voltages to operate. I know I could easily make a module which replaces all 8 ICs with a single IC of static RAM which operates with only 5Vdc and consumes less power than a single LED. The question is: Would that be useful to anyone ?
  4. The question remains: Why is it people use this seriously antiquated solution as a video amplifier for the Colecovision ? I am presently working on RF modulator replacement for the VIC-20 and C64 (VAMP-20 and VAMP-64) and I will likely use the THS7314 and/or THS7374 which cost very little and do an amazing job. A collaborator had a programmer develop a 'test' cartridge for the CV and it allows the display of test colors so I will probably investigate the video chip TMS99x8 Y R-Y B-Y output signals to create a converter. Converting to what exactly is to be determined. Of course it will be nothing like the F18 which generates VGA signal.
  5. The schematic shown here has serious problems. The most obvious is the 47uF capacitor. If you look at dedicated video amplifiers circuits available on Digikey, the THS73XX family datasheets all recommend a linking (DC isolation) capacitor of 330uF or 470uF on the output side. This makes perfect sense as the impedance load of 75Ohms combined with this capacitor acts as a high pass filter with a cutoff frequency of 45Hz. TV have a refresh rate of 30Hz so the value of the capacitor must be at least doubled. The other nonsense is the 10kOhm resistor on input. The input impedance of most op-amps on positive input is already near infinite so adding 10kohms is ridiculous. Finally, the LM318 is a totally antiquated video op-amp. Today, you pay less for better op-amps.
  6. I am eslapion and I have restarted production of the Behr-Bonz multicart. I have about 30 units available. Complete information: New lower price - 36$US or 32.50 Euros! The printed circuit boards have arrived in Montreal. There is a new menu in the Behr-Bonz cart. A friendly menu for the friendly computer! Thank you e5frog ! Up/Down cursor keys to browse, or F1 and F7, select with Return. Browsning can also be done with joystick up/down + fire. Quick select using key 1-8 then choose game with lettered keys according to column on the right. This cartridge designed for your Commodore VIC-20 computer comprises 127 games, all of which were originally published as game cartridges between 1981 and 1984. No additional expansion is required to play them, except a joystick and, depending on the game, a pair of paddles. The new Behr-Bonz will be slightly different from the Original with a new color in the menu and a button to reset to menu without the need to turn your VIC-20 off and on. The Behr-Bonz multicart circuit board is exactly the same physical size as a Commodore made game cartridge so it can fit in the plastic case of a game you already own (4.5 x 9 cm). No plastic case is provided. Just like original Commodore cartridges it uses gold plating to protect your cartridge port connector and for the longest possible lifespan. It is protected by a 90 day money back guarantee. Please note that out of the 100 original units made in 2008, not a single one was found to be defective nearly 7 years after their initial release. -The price per unit of the Behr-Bonz multicart is 36$US or 32.50 Euros. Quantity discounts are available on quantities of 5 units or more. -Shipping to the US is 10$US, Australia, South America, all EU countries and Canada is 12$US or 11 Euros - shipping cost is the same wether you order 1 or up to 7 units. - YOU MUST SPECIFY WETHER YOU WANT A PAL OR NTSC VERSION - if this information is not specified then I will determine it myself according to the video standard available in the country of the shipping address If you are interested, just send an e-mail indicating how many you would like to purchase to eslapion(aT)videotron.ca with the subject "Behr-Bonz purchase". You will be added to a mailing list and informed - DO NOT PM ME HERE! E-mails coming from unknown e-mail addresses with any other subjects will be deleted by the spam filter. There is at least 3 improvements to the original cart: - A "reset to menu" button. The original cart would send you back to the selected game when resetting the VIC because of the way it "locks" to the selected game to prevent games who write gibberrish in the IO2/IO3 region from causing problems. - Improved PAL version menu colors. The colors of the menu are white text on black background and a blue border. This is an indication the version is 2015. - Games can now be accessed quickly by pressing numbers 1 to 8 then the associated letter FAQ: * How do I disable the Behr-Bonz ? Presently, if you want to return to BASIC startup without disconnecting the cartridge, just press '6' then press 'K' from the menu. This actually selects one of the Scott Adams game but if you never start the game, you're effectively disabling the Behr-Bonz and falling back to an unexpanded VIC. * How do I jump directly to my favorite game without having to scroll hundreds of titles ? Press numbers 1 to 8 then press the letter associated with your favorite game. All games can be accessed quickly by pressing one number then one letter.
  7. There was an extensive discussion about gold plating on edge connectors and the impact on the cartridge port connector on Denial. One of the things discussed is the fact VIC-20crs use very cheap connectors compared to earlier models of the VIC-20. Also, in the past, I have seen only one VIC-20 where inserting and extracting cartridges was really difficult and it turns out the top plastic case/keyboard was from a VIC-20cr while the bottom and board was a 2-prong VIC. The 2 halves from different generations of VIC-20s don't match so well at all.
  8. AFAIK, these are unarchived and I would love to lay my hands on Tiny Basic Compiler.
  9. Special offer! Buy one or more TOLB and get a 10% discount on up to 5 PLAnkton modules - you also save on shipping when you combine orders.
  10. Sizzling summer special! Get PLAnkton at it's older price for the summer: 14 Euros or 15.50$US per unit Add one or more TOLB to your order and get 10% discount on that special price, that's 12.60 Euros or 13.95$US per unit! Shipping remains the same price. This offer expires Sept.20th 2017 Also, customers ordering 10 units or more get a 25% discount. Customers ordering 5 units or more get a 20% discount. TOLB discount does not apply to these quantity discounts. ----- 900 units sold as of June 23rd
  11. I assume you know what the C64 Reloaded is, right ? Maybe you've heard about PLAnkton too ? It's a PLA replacement I also make and sell. Sidenote: I strongly suspect I will be dead in another 50 years.
  12. For a few months now, a replacement for the 8701 clock generator chip used on Commodore 64 boards 250425, SX-64, 250466, 250469 and the Commodore 128 has been in preparation. Works on the C64 Reloaded too! A prototype has now been successfully tested. I present to you The Other Little Board (or 8701 upside down...) Pricing is 11$US or 10 Euros per unit. Shipping cost is the same as with PLAnkton; shipping a small packet (up to 12 units) to the US is 7$. Shipping cost for Europe is 8 Euros, Australia and South America is 9$US. The product is strictly shipped with antistatic protective packaging. It is covered by a 90 days money back guarantee and a 3 year replacement guarantee afterwards. NTSC and PAL versions with appropriate frequency signals are available. Both versions cost the same price. Main features: Gold plated pins 3 year guarantee Onboard oscillator makes it independent from the C64 crystal and easy to convert a C64 from PAL to NTSC and inversely Consumes only 9mA of power (a genuine MOS 8701 consumes 25-30mA) AVAILABLE NOW for both PAL and NTSC C64 and C128 computers!! Please indicate your interest in this thread. Feel free to ask all technical questions you may have.
  13. The short answer to the OP question is quite straightforward; because it's tough! For one thing, the output from the VIC-II is about the same as S-Video. That is, it is an analog signal with a 15kHz scan rate and color encoding based on the phase shifting of a specific frequency signal. One could say the Flickerfixer converts the Amiga video signal to VGA and it's quite simple by today's electronics standard. Well, internally, the Amiga outputs video in the form of a 12 bit digital signal (RGB with 4 bit per color) with separate vertical and horizontal sync signals. Capturing this information, putting it into high speed RAM and then "playing" it back at twice the speed is easy in terms of digital technology. The C64 as well as the VIC-20 both lack the digital information and going to VGA involves converting luma, chroma and sync signals that are all jumbled together, into RGB digital information and then double the scan rate. This is no easy feat. It's the same as converting the output of an S-VHS VCR into VGA. You also have the added problem that the C64's video signal isn't exactly standard so even if you have a machine that can convert a VCR's output to VGA, you have have junk all over the place. I too have the Nextvision N6, I love it but it is out of production. I suppose nowadays, you're more likely to look for an S-Video to HDMI converter and the compatibility problem remains the same.
  14. Hi people, I am mostly into Commodore 8 bit machine such as the VIC-20, Commodore 64 and Commodore 128 but I also have a profound admiration for a number of Atari arcade machines such as Pong, Asteroids, Centipede and Marble Madness. I was rather surprised there is no specific forum section related to these great machines and their internals on AtariAge. I have noticed there is an area devoted to arcade machines in general but there isn't one for Atari ones specifically. Cheers everyone!
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