Xetec 32k
Posted: Mon Jan 23, 2017 6:54 pm
I got this as a throw-in for a messed up e-bay order (with my remaining order). I haven't seen this before. Is it rare? It does work, I just tried it with a 32k game.
The Commodore Vic 20 Forum
http://sleepingelephant.com/ipw-web/bulletin/bb/
http://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?t=8371
Sure: I carefully took it apart without damage..Its the same cart shell type as a standard Commordore with locking tabs in the rear and front with a center screw. Looks like a DRAM card with a refresh circuit.eslapion wrote:I don't know if it is rare but I find it very interesting. I suppose it's worth adding to the Wiki.
Can you show the board inside ?
Looks like a card nobody is going to replicate anytime soon!!norm8332 wrote:... Looks like a DRAM card with a refresh circuit.
Oh oh.... I think another $2,500 ebay listing is in the works!dragos wrote:Hmm, I sure thought I had one of those, but I guess not. let me know if you decide to sell it
I don't think so, it is just a ram expander, not a game. The other one is open to offers by the way..that price is not written in stone.CanadaPhil wrote:Oh oh.... I think another $2,500 ebay listing is in the works!dragos wrote:Hmm, I sure thought I had one of those, but I guess not. let me know if you decide to sell it
Some people may be impressed by uniqueness and looks, personally, I am always more interested in functionality. From that stand point, this Xetec expander uses 8 DRAM chips, just like a C64 and half a dozen 74LS chips so it must be a power hog which turns old 2-prong PSU VICs into a good winter home heating system.CanadaPhil wrote:Oh oh.... I think another $2,500 ebay listing is in the works!dragos wrote:Hmm, I sure thought I had one of those, but I guess not. let me know if you decide to sell it
Then you'll have to buy the new Ray Carlsen 2-prong power supply that outputs 9VAC at 3 amps.eslapion wrote:...so it must be a power hog which turns old 2-prong PSU VICs into a good winter home heating system.
Not going to change anything for the 5V regulator which is internal on these VIC-20s - for every single watt of power they provide to the rest of the computer, they dissipate 800mW of heat.RobertBe wrote:Then you'll have to buy the new Ray Carlsen 2-prong power supply that outputs 9VAC at 3 amps.eslapion wrote:...so it must be a power hog which turns old 2-prong PSU VICs into a good winter home heating system.
Personally, I don't think I would ever replace the original 1981 6502 and 6522s of my PET style keyboard VIC-20 with CMOS versions because I use a 32k RAM expansion that guzzles up power and makes the regulator overheat.RobertBe wrote:Then it's time for less power hungry R65C02 and 65C22 chips.
That's a huge amount of power for the 2-Prong PSU VIC-20. It's about the same as is used by the Protecto-80. The 5V regulator already dissipates about 4W of heat when nothing is attached, a 150mA load on the cart port is 750mW of power and this will increase the regulator dissipated heat by 600mW.norm8332 wrote:It doesn't draw much. It doesn't heat up the regulator. It draws 100-150 ma max.
A lot of what you said depends on the input voltage. Two prong Vic-20 were supplied with power supplies that ranged from 9V to 11V AC. The lower input voltage with a 9V supply will allow the regulator to run cooler with higher efficiency. Or you could do what I do and supply a regulated 9.75VDC Using a buck converter and a 12V switching supply. This supplies the regulator with about 7.5V After the full bridge voltage drop. This is only 0.8V above the dropout voltage of the regulator and allows you to get up to 85% efficiency from it. It runs barely warm with this setup.eslapion wrote:That's a huge amount of power for the 2-Prong PSU VIC-20. It's about the same as is used by the Protecto-80. The 5V regulator already dissipates about 4W of heat when nothing is attached, a 150mA load on the cart port is 750mW of power and this will increase the regulator dissipated heat by 600mW.norm8332 wrote:It doesn't draw much. It doesn't heat up the regulator. It draws 100-150 ma max.
The total dissipated heat will rise from 9W (regulator and computer) to 10.35W (computer, regulator and RAM cartridge).
As I said, the ultimate expander I used to sell would draw about 10mA of power if it had only RAM (32k, just like the Xetec). It would rise to about 20mA if you added an EPROM.
The reason why the C64 board 250466 consumes so much less power compared to previous C64 boards is mainly because it uses 2 64kx4 DRAM chips instead of 8 64kx1 chips.
Of course, if you have a VIC with a round power connector and use a C64 power supply, the impact will be negligible.