MOS 8568 VDC 80 column IC video chip for Commodore 128D. Slightly blemished. NOS

$57.0 Buy It Now or Best Offer
free,30-Day Returns

Seller Store uniquesoftware
(7809) 100.0%,

Location: Salt Lake City, Utah
Ships to: US,
Item: 305118556537

Restocking Fee:No
Return shipping will be paid by:Buyer
All returns accepted:Returns Accepted
Item must be returned within:30 Days
Refund will be given as:Money Back
Compatible Brand:For Commodore 128D
MOS (Commodore):MOS (Commodore)
Type:IC chip
MPN:315092-01

New or like-new MOS 8568 VDC video chip for the Commodore 128D in 80-column mode from U.S. seller. Slightly blemished top (see photos). Despite the top of this chip being slightly blemished please notice how pristine and nice looking the legs of this chip are (see photo #3). Fifteen or twenty years ago we picked up over 50 of these from a major corporation that used to refurbish Commodore computers. They came to us in factory looking chip tubes. Most of the chips in the tubes had identical date production codes and the chip legs appeared to be very shiny and unbent which is typical for new chips. So, we assume they are new or at least in new-like condition. We picked up around ten thousand other Commodore and Amiga chips from the same source and have sold thousands of them over the last 12 or 15 years with great success and very few problems. We ship these chips in special static-resistant chip boxes with black crisp anti-static foam to protect them.Be advised, however, that the video chip is often not the problem when a Commodore 128D has no picture or video output. Oftentimes a blank or abnormal screen display is caused by a defective power supply, blown out ram chips, a blown fuse, other bad chips or some other problem. So, if you haven’t ruled out other causes of a video failure on your Commodore 128D you cannot assume that the video chip is necessarily the problem. Still, it never hurts to have a spare video chip or two on hand! Also, in order for the 80-column mode on the Commodore 128D to appear on your screen you must have the 40/80 button on the keyboard locked in the down (80-column) position. You must also be using a monitor with RGB capability and have an appropriate RGB cable connected to the computer and the monitor. Also, most of the monitors that support the 80-column output from the Commodore 128D have a switch or button (on the monitor itself) which must be set properly to allow the RGB 80-column input. Obviously the monitor must also be functioning properly in the RGB mode. If any one of these 4 things is not configured or functioning properly you will not be able to view the 80-column output from the Commodore 128D– even if the chip is functioning properly. So, before ordering this chip PLEASE make sure that your problem isn’t just a configuration problem– unless you just need a spare. The photo shown may vary slightly from the actual chip you receive and the date production code may be different. These chips are in nice overall condition but may not be in mint condition due to the fact that they have been stored in chip tubes which may have scratched them slightly or caused other minor blemishes. We take note of the production date codes of all chips shipped and oftentimes put little warranty stickers on the bottom of the chips which we ship in order to make sure that any returns are chips which we actually sold. Any returned chips which do not match the production date codes or which have missing or damaged warranty stickers will not be refunded. If you don’t want little warranty stickers on the bottom of these please contact us before ordering to make special arrangements. Please Help Us: We are reaching out to anyone with greater expertise about this chip to try to find out if this chip can also be used in place of the 8563 VDC chip used on a regular Commodore 128. We do not believe this is possible unfortunately. Apparently this 8568 VDC chip for the 128D has 64k of video ram whereas the 8563 VDC chip for the regular Commodore 128 only has 16k of video ram. Our situation is that we have relatively more of these 8568 versions for the 128D than we have of the 8563 versions for the regular 128. So, if they are interchangeable we would like to mention it in our Ebay listing of this chip. If any Commodore technical experts out there can shed light on this matter we would appreciate it. We will need to get credible and hopefully multiple verification(s) of this matter before revising our listing. We don’t want to give our customers any misguided information. From what we can tell so far the 8568 and the 8563 chips ARE NOT electronically interchangeable. So, barring any further information, we do not recommend using these 8568 VDC chips as a substitute for the 8563 VDC chips on a regular Commodore 128. Thank you! Note: Our shipping price is a couple of dollars higher than our actual shipping cost on these normally because of our cost on the special anti-static boxes which we ship them in. We have been selling Commodore hardware, parts and accessories for over 37 years (since 1983) and have a great reputation. One Ebay member (who seems to be very well informed about these chips) provided the following information about the differences between this 8568 VDC chip for the Commodore 128D and the 8563 VDC chip used on the regular Commodore 128: Regarding the differences between the MOS 8653 and the 8568, they are in pinouts and corresponding functions, not the amount of video RAM that can be addressed. Both VDCs are able to address 64KB of video RAM, which is something that is determined by a ROM-based setup table that is read as the system comes up. Electrically, the 8563 and 8568 are mutually incompatible. Some of the glue logic that was used with the 8563 is integrated into the 8568, with corresponding differences in the pinout. In particular, note that pin 48 of the 8563 is CAS, but the same pin of the 8568 is RAS. Similarly, pin 1 of the 8563 is CCLK, but the same pin of the 8568 is CAS. Additionally, the 8568 has an active-low IRQ output on pin 9 that is not present on the 8563. /IRQ is asserted when bit 7 in the status register (visible at $D600 in the C-128D memory map) goes from 0 to 1. Pin 9 of the 8568 is not connected in the C-128D. The same pin of the 8563 is connected to the 8502 R/W output in the « flat » C-128. That difference alone would result in outright system failure were an 8568 to be plugged into a « flat » C-128 mainboard. Aside from the electrical differences, some timing specs are different as well—the 8568 read access times are faster than the 8563, plus some other details that I have forgotten over the years. I seem to recall the faster timing of the 8568 was used in the C-128D to speed up the video DRAM refresh rates, making for a snappier display. A historical note: Commodore at one time had plans to build a UNIX server powered by a Zilog Z8000 MPU, in which the 8568 would be used for the console display. That was why the 8568 was given an IRQ output, since I/O is typically interrupt-driven in UNIX. The project never got out of the prototype stage. In summary, the two VDCs are not electrically compatible in any way. I hope this information helps. We assume that the information which this Ebay member provided for us is accurate but we haven’t independently verified the information he provided to us. We always encourage potential buyers to independently verify as much information about these chips as they can before placing an order.

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MOS 8568 VDC 80 column IC video chip for Commodore 128D. Slightly blemished. NOS

Frequently Asked Questions About MOS 8568 VDC 80 column IC video chip for Commodore 128D. Slightly blemished. NOS in My Website

What are the best-selling MOS 8568 VDC 80 column IC video chip for Commodore 128D. Slightly blemished. NOS on humusjardin.com?

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