Replacing 80xx series ICs?

I have to agree with the above. Its shocking how quickly an experienced repair guy can pinpoint a problem on a completely unknown piece of equipment-and he never ever replaces a whole bunch of parts hoping to hit the right one. One of the first thoughts I had after reading the original post was that the guy didn't seem to be going about the repair the right way. Almost always the problems seem to be bad solder joints, bad caps, bad power supply, bad component that typically runs warm/hot. There is a lot of stuff I would check before replacing mass quantities of ICs. I worked with a guy once who was really good at repairing electronics, for about a week, I learned more than I ever thought possible.

--Dan

OK, since you are so confident about this, let each put up $100 cash. You find the EPROM and I set up the programming and verification environments in a third party site. Your familly get the cash if it lasts 100 years and mine get it if not. Perhaps some one in vegas would be willing to hosts this bet.

Sorry, Meindert, but you are wrong. According to the 1990 INTEL Peripherals Databook the 8279/8279-5 is a Programmable Keyboard / Display interface. The datasheet is dated Sept 1987 and is on pages

The 8272A is a Single / Double Density Floppy Disk Controller chip. The data sheet is in the 1990 INTEL Peripherals Databook and is dated Nov 1986. It is on pages 4-1 to 4-31. This was used on the original IBM PC on their floppy disk controller card. The clones used the NEC version because it was cheaper.

inside

Oops! I mixed up some numbers here.....

But then again, is there really code inside the 8279? I vaguely remember that the SDK-85 from Intel also had this chip and that programmable only meant that you could set it up for a variety of keymatrices and display configurations.

Meindert

Hi all It's true. 8279 is "programmed" at the boot of the CPU by the program. It was used to interface the keyboard.

I remember to have designed a system, at the same period, with the same components. The board using this ICs serie was the CPU, and should contain the eproms with the program.

I suppose the board is not a standalone, but one of the many boards the system was made of. You should find I/O boards, probably a 7 segment LED display, push buttons simplified keyboard, battery saved RAM...

-- Guy Pastuzak

Adresse ANTISPAM ANTISPAM address

"Michael A. Terrell" a écrit dans le message news: snipped-for-privacy@earthlink.net...

Another saved RAM is probably located on another board

-- Guy Pastuzak

Adresse ANTISPAM ANTISPAM address

On Sat, 25 Feb 2006 17:32:16 GMT, "Michael A. Terrell" put finger to keyboard and composed:

The 8155 has on-chip RAM.

- Franc Zabkar

By programmable the databook means that you can change the configuration of i/o etc with your application. Usually done at power up. The device has NO code, your write some data in some registers.

Pieter

Actually it is a whole 2 kB.

I've never used the 8155 and don't think I have a datasheet in my collection, so I wasn't familar with it.

The datasheet of 8155 is available at the above as MSM81C55-5RS

Allen

The datasheet of 8155 is available at the above as MSM81C55-5RS

Allen