ACS19@UHUPVM1.BITNET (08/01/86)
Well, let me try again... The keyboard clock does work, but not with the 6301v1.0 (which is rev. 1). That is the chip of the early 520STs sold (of which I have one). The good news is that the mod works perfectly with the new 520 and 1040 which have the rev 2.0 chip. The keyboard part number that works is C070240-011. If you have one of the older keyboards, I don't think you can use the mod (I tried for over two days to get it to work -- I wish someone would tell me what the difference between the revs is!!!!!!). I am getting together a little doc to send over the network which could be followed by a layman (not a schematic alone -- hopefully I can draw a board with the character set) Anyway, if someone at Atari is listening, please tell me what the difference in the two chips are. I have been on Compuserve in the developer's sig, and there are no documents which explain the difference, not even the new hardware manual. I could contact the company that makes the chip, but that would be a hassle. Mike
ACS19@UHUPVM1.BITNET (08/22/86)
The mod just posted is not the best way to get the keyboard chip to keep the time. Youy must keep the reset pin high on the chip when the power is off, or the time will just freeze. To do this, I have used a nand gate circuit. Adding another reset button is silly (in my opinion) when it could be done with the proper circuit. Also, the reset line must go low when you hit the rest button, or the keyboard will not work correctly. I will post the mod this weekend, so all can see. And yes, their are two different versions of the chip, I have had two in my hands, one says V01 and the other says V02. To me that is two different chips Perhaps the little chip on the keyboard is different, but the appears to be a simple buffer (the little chip by the 6301). Mike
mugc@utecfa.UUCP (ModemUserGroupChairman) (08/23/86)
Someone writes: > The mod just posted is not the best way to get the keyboard chip to keep the > time. Youy must keep the reset pin high on the chip when the power is off, or > the time will just freeze. To do this, I have used a nand gate circuit. > Adding another reset button is silly (in my opinion) when it could be done with > the proper circuit. Also, the reset line must go low when you hit the rest > button, or the keyboard will not work correctly. I will post the mod this > weekend, so all can see. I don't want to start a my mod is better war, and I'm only replying to the above to clear some misconceptions that the above article might create. I don't care whose mod is used, and if I had known that someone was going to post a mod, I would probably not have posted mine. To reply to some specific points raise above: Yes the *RESET line should be kept high, and if you look at the circuit I posted, you will find that it *is* kept high. Conversely, when you press the reset button the line will go low. Please do not post erroneous information. The second reset button is the only one you need to use to reset the whole system. Yes, it is a bit of a hack, but personally I thought it was a reasonable solution given the constraints. BTW, the mod I posted is quite sufficient if you are going to be using the ST for most of the day, and will leave if off at night. If, on the other hand, you want to just use it for a few hours a day, you should think of getting larger capacity Ni-Cad cells, and making a real charging circuit for higher charging rates. Finally, the mod given above works. I have been using it for about a week now. anees