Search found 282 matches
- Tue Feb 16, 2021 4:55 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
Interesting... My knowledge of digital electronics is at novice level at best, so bare with me, but doesn't 200ns translate into 5Mhz? 200ns would be 5MHz if it was a simple period to frequency conversion. 200ns is how long it takes from presenting a row-column address pair and saying "READ!&q...
- Sat Feb 13, 2021 5:48 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
If you have slow ram chips, and you use them only from $0000 to $B4000 and from $C000 to $FFFF, where only the 6502 is actually doing active reads, using fast chips for the area frequently accessed by the ULA, would that work? Good thought! As Kenneth said -- and definitely not under current hardwa...
- Fri Feb 12, 2021 5:33 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
They are TMS4164 -20 NL, date code AP8432 They seem to be genuine, rubbing with IPA and acetone did not reveal anything. They are obviously second hand with solder marks on their pins small scratches here and there. Oh, and I confess, I bought them for a Sinclair Spectrum and testing them on it. 😊 ...
- Thu Feb 11, 2021 4:51 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
I have a set of TI 6154 chips I bought from China Skipping past the obvious objections regarding fakes, and relabelled chips, what is the FULL numbering from the top of the chip? Often, the part number is immediately followed by a speed indication, and there are plenty of 4164-like chips that are t...
- Tue Feb 09, 2021 5:19 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
... further thought! In an actual Oric, the memory test relies on this "missing address line" situation to distinguish between a 4164 (64k/48k Oric) and a 4116 (16k Oric) bank With the quarter size DRAM chip (16K), now there is nowhere for A7 to go. So whether the row/col address bit 7 is ...
- Mon Feb 08, 2021 4:59 pm
- Forum: General Discussion
- Topic: ORIC NEXT
- Replies: 37
- Views: 15792
Re: ORIC NEXT
- Upgrade the ULA to add registers allowing to move the "display window" - Upgrade the ULA to add registers to redefine the 8 colors by remapping them with a custom palette that can be changed by the user While you're in there tinkering with the ULA :- A parallel attributes mode! That wil...
- Mon Feb 08, 2021 4:49 pm
- Forum: Hardware hacks and extensions
- Topic: DRAMARDUINO - Dram tester with Arduino
- Replies: 53
- Views: 75899
Re: DRAMARDUINO - Dram tester with Arduino
if I put a 4164 and test it as 41256, it still passes OK, and strangely it also takes as long as a real 41256. Shouldn't it sort of "hit a wall" and return an error when the address incrementing loop goes over XA7 and come to a non-existent XA8 bit? Hello! I suspect what you're doing is t...
- Sat Feb 06, 2021 7:04 pm
- Forum: Hardware hacks and extensions
- Topic: TSN 1-2450A instead of LM7905
- Replies: 27
- Views: 14688
Re: TSN 1-2450A instead of LM7905
I've no idea what the Arduino circuit is doing (or trying to do), so won't comment on that too much -- I can't think of a good reason to drive the ROMDIS low at the same time as reset, while RESET is low the 6502 is dead anyway, so won't see the ROM whether it's there or not. I think the mess you se...
- Sat Feb 06, 2021 6:56 pm
- Forum: Mags and books
- Topic: OUM magazine scans...
- Replies: 84
- Views: 54502
Re: OUM magazine scans...
What a blast looking through the early OUMs -- I never actually saw the first 20 odd issues when they originally came out, and no longer have full paper versions of those up to 64 anyway. Just to say if Dave Utting is still looking for that ULA circuit diagram (£20 reward rising to £50) I can help h...
- Fri Feb 05, 2021 5:41 pm
- Forum: Hardware hacks and extensions
- Topic: TSN 1-2450A instead of LM7905
- Replies: 27
- Views: 14688
Re: TSN 1-2450A instead of LM7905
As for the capacitor, any 10uF small electrolytic, rated at 10v to 16v should fit in there. Modern electrolytics tend to be slightly smaller, value/voltage being the same, than older ones. It's not under any particular stress (temperature, heavy currents) like those used in switch mode power supplie...
- Fri Feb 05, 2021 5:33 pm
- Forum: General Discussion
- Topic: Hello from Bristol
- Replies: 29
- Views: 12399
- Tue Feb 02, 2021 4:39 pm
- Forum: Operating systems, utilities and other serious software
- Topic: dflat language update
- Replies: 72
- Views: 28116
Re: dflat language update
- dim a$[5,4]: I should be clearer - but arrays start from index 1 not 0 :-) - input a$: Not sure I have understood the problem? If you type in the quotes, it is correct for it to be captured as part of the input - or something else you are raising? It seems like the confusion over array-counting i...
- Thu Jan 14, 2021 6:19 pm
- Forum: General Discussion
- Topic: FebrORIC?
- Replies: 8
- Views: 4904
- Fri Dec 25, 2020 4:58 pm
- Forum: 6502 assembly coding
- Topic: Oric Atmos ROM 1.1b Disassembly - browsable listing by [raxiss]
- Replies: 3
- Views: 5337
Re: Oric Atmos ROM 1.1b Disassembly - browsable listing by [raxiss]
Excellent resource, and what a Xmas gift! Already saved for posterity! :) Note that at #E43A ... "trigonometric function data" ... is it time to acknowledge the easter egg? perkin (~)> echo "MICROSOFT" | rev | hexdump -C 00000000 54 46 4f 53 4f 52 43 49 4d # Hi bits, hi bits, oth...
- Thu Dec 10, 2020 4:38 pm
- Forum: Hardware hacks and extensions
- Topic: IJK-egopad the joypad for Oric by [raxiss]
- Replies: 32
- Views: 17402
Re: IJK-egopad the joypad for Oric by [raxiss]
Hi all Why don't you have launched some sells with paypal friends process, to reduce costs Further to the answer given by @iss, using Paypal "Send payment to my friend" to pay for goods and services is a red-flag for lots of people, it is the hallmark of scammers and conmen who have no in...