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Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Wed May 15, 2019 1:24 pm
by waltermixxx
Hi there, I'm wondering what is the best approach for this?
I find myself in the awkward position of not being able to burn 2716 eproms,
but I can burn 2764's.

On the REV D, there are points on the board near U12 that allow you to connect to A11 and A12.
here is what I have tried with no success... :( below is the REV. D. schematic portion, and my handy work.

U12 socket Pin 21 - goes to the A11 point on the board
U12 socket Pin 18 - is grounded (not changed)
U12 socket Pin 20 - is connected the way it usually is to pin 15 of the LS138 (inverter is not used on this new board I dont think)
2764 pin 1 to VCC
2764 pin 2 to the A12 point on the board.

and this does not seem to work... anyone try this? have I missed something fundamentally obvious?

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Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Wed May 15, 2019 8:23 pm
by Steve Gray
Walter,

I believe you'll need to change the jumpers from U15 to U73. These feed the address lines to be decoded to 4 separate chips selects, one for each ROM socket. When you combine the 4 ROMs into an 8K rom you always want the one socket selected. By changing the jumpers you are disconnecting A11 and A12 and using the outputs BK0 and BK1, which are inverted. This will cause the output of the LS138 to always have Y3 output LOW which is the chip select for the first BASIC ROM socket (U9). You will need to change the jumper at U16 pin 12 so that it's low.

Steve

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 2:37 am
by dave
Steve Gray wrote:
Wed May 15, 2019 8:23 pm
. . . You will need to change the jumper at U16 pin 12 so that it's low.
That should be "... change the jumper at U16 pin 12 so that it's active low."

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 2:40 am
by Steve Gray
dave wrote:
Thu May 16, 2019 2:37 am
Steve Gray wrote:
Wed May 15, 2019 8:23 pm
. . . You will need to change the jumper at U16 pin 12 so that it's low.
That should be "... change the jumper at U16 pin 12 so that it's active low."
Yes, thanks for noticing that.

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 5:26 am
by waltermixxx
U16 the 4 inverters are not used with the 2716’s or 2764’s.
There are also no jumpers there. Because there is no schematic of the reproduction Rev.D, we need to make notes of these changes.

Cheers.

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 2:51 pm
by Steve Gray
Walter, you also mentioned to me that BK0 and BK1 are not connected, which also affects the ability to have multiple 8K roms in the BASIC sockets. I know there's little chance someone would use that but you never know. Of course we can run a couple jumper wires to re-connect them.

Steve

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 3:18 pm
by gekaufman
If you (or anyone else) needs 2716's burned let me know - happy to help.

I can burn most any prom, eprom or eeprom including 1702A, 2716 etc.

- Gary

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 8:10 pm
by waltermixxx
gekaufman wrote:
Thu May 16, 2019 3:18 pm
If you (or anyone else) needs 2716's burned let me know - happy to help.

I can burn most any prom, eprom or eeprom including 1702A, 2716 etc.

- Gary
Thank you Gary, that is most kind of you. :)
Happily, Steve Gray lives not too far away, and is actually coming over tonight for "OSI Night"
where we hope to mess around with his colour interface and further explore the fun and excitement that is the OSI computer :)
(we will actually have 3 fully functional OSI computers in the same room....) :)
Cheers.

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Thu May 16, 2019 8:11 pm
by waltermixxx
Steve Gray wrote:
Thu May 16, 2019 2:51 pm
Walter, you also mentioned to me that BK0 and BK1 are not connected, which also affects the ability to have multiple 8K roms in the BASIC sockets. I know there's little chance someone would use that but you never know. Of course we can run a couple jumper wires to re-connect them.

Steve
perhaps in the interest of fun, tonight when you come over, we can explore that further before settling on the 2716's you are bringing me.
bring them either way, but it might be nice to get 8k eproms working :)

Cheers Steve, see you tonight. :)

Re: Klyball REV. D 600 - replacing 4 basic 2716's with 1 2764....

Posted: Sun May 19, 2019 1:46 pm
by waltermixxx
Ok so we didn’t really play much with the 8k 2764. We played mostly with the colour card, and who could blame us, it’s very cool. The colours are vivid.

We did notice that on my 600 Kyball Rev. D, my 2.5 amp power supply wasn’t able to maintain a voltage above 4.5 volts with my non low power 2114 ram chips. As a result, the displayed rgb was much dimmer on my Rev. D. If I removed 2114, and used only the Ram/Rom 32k Ram upgrade card that uses a 62256 low power chip, I would see little to no voltage drop at all and a brighter rgb signal.

I ended up finding a 4amp power supply, so I re-installed the power hungry ram to get the full 40k. I think instead of finding low power 2114 chips, it’s easier and cheaper to get a better switching 5volt power supply.

Cheers.