Sunday, August 2, 2015

I am absolutely amazed that this kit continues to sell in numbers. I have sold over 60 boards and kits, all over the world. Thanks so much to everyone who has ordered from me, and I hope that this amazing design, by Richard42, will help you to continue to enjoy your vintage computer, be it a Commodore 128, or any other. Unfortunately, family pressure is forcing me to temporarily discontinue availability of the kit. I hope to resume building them, in the future.

Thursday, March 6, 2014

Video DAC Assembly Information

This post is taken directly from a post that I made on Erik Klein's Vintage Computing Forums.
Here are a list of the parts required to build the video DAC.

QtyReferencePart NumberDescription
1R13309XBK-NDRES 309 OHM 1/4W 1% METAL FILM
1R14324XBK-NDRES 324 OHM 1/4W 1% METAL FILM
1R15365XBK-NDRES 365 OHM 1/4W 1% METAL FILM
2R4,R54.64KXBK-NDRES 4.64K OHM 1/4W 1% METAL FILM
1R64.32KXBK-NDRES 4.32K OHM 1/4W 1% METAL FILM
1R1913.0KXBK-NDRES 13.0K OHM 1/4W 1% METAL FILM
3R10,R11,R1210.0KXBK-NDRES 10.0K OHM 1/4W 1% METAL FILM
3R7,R8,R915.0KXBK-NDRES 15.0K OHM 1/4W 1% METAL FILM
4R3,R16,R17,R1875QBK-NDRES 75 OHM 1/4W 5% CARBON FILM
1R12.2KQBK-NDRES 2.2K OHM 1/4W 5% CARBON FILM
1R23.3KQBK-NDRES 3.3K OHM 1/4W 5% CARBON FILM
4C2,C3,C4,C5478-3193-NDCAP CER 0.1UF 50V 20% RADIAL
1C1493-1144-NDCAP ALUM 10UF 100V 20% RADIAL
1IC2296-3577-5-NDIC TRIPLE 3-IN NOR GATE 14-DIP
1IC1TC74ACT244PF-NDIC BUFF/DVR TRI-ST DUAL 20DIP
1IC3296-4348-5-NDIC QUAD 2IN POS-NAND GATE 14-DIP
1X1621-009-260-042-NDCONN DSUB PLUG 9POS R/A GOLD
1IC4AD8044ANZ-NDIC OPAMP VF R-R QUAD LP 14DIP
1POWERA1921-NDCONN HEADER VERT 2POS .100 TIN
1H2A1923-NDCONN HEADER VERT 6POS .100 TIN

And, the pinout of the H2 (video) connection, from left to right, with the DE-9 connector facing up, is:

Ground, horizontal sync, vertical sync, red, green, blue

The power connection pinout, from left to right, is:

+5 VDC, ground

The GBS-8220 board comes with 2 pigtails. Plug them in, as described in the 8220 manual, and the video DAC will be powered by downstream power from the 8220. Power the 8220 with a standard AC/DC power adapter.

You can use the following parts, from DigiKey, to put connectors onto the supplied pigtails, that will plug in to the DAC board.

QtyPart NumberDescription
8A100453CT-NDCONN SOCKET 22-26AWG TIN CRIMP
1A99617-NDCONN RCPT HSNG 6POS CST-100 II
1A99613-NDCONN RCPT HSNG 2POS CST-100 II

The DAC can be plugged directly in to either a Commodore 128 RGB connector, or to the back of a CGA or EGA IBM video card. Please note that, on an EGA card, the DAC only works in the CGA (low-res) modes, and not in 640x350.

In response to a number of requests, here is the schematic.  It's a bit messy, but it should be usable.

Wednesday, March 5, 2014

Parts Inventory

Just a quick note on my inventory:

DescriptionQuantity on HandQuantity on Order
C128 DAC PCB40
DAC Parts Kit60

Unless I say that I have parts in stock, here, any orders will be shipped as soon as their parts come in. Negative inventories represent orders received for which I do not yet have the parts.

Commodore 128/ CGA Video DAC Board Available

I just completed a new build of Richard42's fantastic Commodore 128 video DAC board.  This is a fantastic little board that, in combination with a Gonbes GBS-8220 arcade RGB scaler, produces great 16 color, with intensity, output on any modern VGA monitor.  To boot, the combination also works great with IBM CGA or low-res EGA cards!

I did two rounds of prototypes, and the following is what the final board looks like.  Please excuse the poor quality of my living-room photos.

Video DAC Front
Video DAC Back
I am now making these available to the vintage community for the price of what the components cost me, plus shipping.

If you would like to purchase one, I am offering several different ways to get it.

Please let me know if you have any comments. I'll work on getting some screenshots, as I was referring to some posted on Commodore128.org, but that forum seems to have gone down, rather unexpectedly.