Hello David, I finished building mine. I am having a problem that I cannot find anyone talking about. The computer seems to do everything correctly until it reaches 254, after which it jumps to 1! The problem is with the microinstruction Ro I AI. I see the bits go ON and then go off immediately. Only the 2nd to the 5th bits remain ON. I tested with LDA14 and putting different values in the memory register 14 to see at what value the issue appears, and it seems to appear more as I get close to all the bits being ON. I have no oscilloscope and I do not know what that could be caused by! Any thoughts?
So if you were to do an LDA 14 (where memory address 14 contained 255), would it only show 254? What happens if you do LDA 14 (where memory address 14 contained 1), do you see a 1? Without being able to look at it first hand, I can only guess. Maybe try: Try another memory address instead of 14 such as LDA 12 (where memory address 12 contained 255). Swapping out the IC's of your A REGISTER with new IC's. Check your pull down resistors on your BUS. Double check the wiring connections as it's incredibly easy to make a mistake. I made many while building mine. If you've finished the carry flag wiring, I would double and triple check that. If you're going from 254 to 1, it seems suspicious to me that something could be off with the carry flag wiring.
@@davidcourtney1398 The content of memory register 14 remains 14, but at the moment, the micro instruction Ro I AI is going to be executed, all the LEDs of the RAM turn on momentarily and then only the 2nd to the 5th bits remain on. I will try other addresses. I think it was the case before I wired the carry flag. I will disconnect the carry flag to confirm it is not related. After that, I might take off all the wiring of the RAM module and rewire it again.
It's a blue gel filter transparency sheet. Something like this: www.ebay.com/itm/12-Colors-Transparent-Color-Correction-Gel-Sheet-Filter-Flash-Diffuser-Kit/332657201531 Edit: I noticed that link is no longer valid. For anyone wanting to find these sheets, search eBay or Amazon for "transparent color gel filter" and you'll find lots of sellers.
![RAM Overwrite Problem [Part 2] *SOLVED* - (Ben Eater 8-bit Computer) SAP-1](http://i.ytimg.com/vi/n71zgHrWBUk/mqdefault.jpg)
![RAM Overwrite Problem [Part 2] *SOLVED* - (Ben Eater 8-bit Computer) SAP-1](/img/tr.png)
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Excellent! I hope to get back and finish the slightly over complicated version of Ben's design that I started last year.
Love this project very much
E possível colocar jogos de 8 bits?
Hello David,
I finished building mine. I am having a problem that I cannot find anyone talking about. The computer seems to do everything correctly until it reaches 254, after which it jumps to 1! The problem is with the microinstruction Ro I AI. I see the bits go ON and then go off immediately. Only the 2nd to the 5th bits remain ON.
I tested with LDA14 and putting different values in the memory register 14 to see at what value the issue appears, and it seems to appear more as I get close to all the bits being ON.
I have no oscilloscope and I do not know what that could be caused by! Any thoughts?
So if you were to do an LDA 14 (where memory address 14 contained 255), would it only show 254? What happens if you do LDA 14 (where memory address 14 contained 1), do you see a 1?
Without being able to look at it first hand, I can only guess. Maybe try:
Try another memory address instead of 14 such as LDA 12 (where memory address 12 contained 255).
Swapping out the IC's of your A REGISTER with new IC's.
Check your pull down resistors on your BUS.
Double check the wiring connections as it's incredibly easy to make a mistake. I made many while building mine.
If you've finished the carry flag wiring, I would double and triple check that. If you're going from 254 to 1, it seems suspicious to me that something could be off with the carry flag wiring.
@@davidcourtney1398 The content of memory register 14 remains 14, but at the moment, the micro instruction Ro I AI is going to be executed, all the LEDs of the RAM turn on momentarily and then only the 2nd to the 5th bits remain on.
I will try other addresses.
I think it was the case before I wired the carry flag. I will disconnect the carry flag to confirm it is not related. After that, I might take off all the wiring of the RAM module and rewire it again.
What is that black sheet on a 7 segment display?
It's a blue gel filter transparency sheet. Something like this: www.ebay.com/itm/12-Colors-Transparent-Color-Correction-Gel-Sheet-Filter-Flash-Diffuser-Kit/332657201531
Edit: I noticed that link is no longer valid. For anyone wanting to find these sheets, search eBay or Amazon for "transparent color gel filter" and you'll find lots of sellers.