Search results

My random thought on this is to use a 256-entry table, and generate the key by just looping through all the characters in the symbol, for each XORing it into the current hash value and then rotating the hash value left by 1 bit. Though I'm also attracted to a prefix trie. The problem with that...

I suppose that's an approach one could take, if one were focusing on the density of the encoding, but I think that's a terrible idea since you then need to entirely rework terminology for one of the most important parameters (and the one that causes the most incompatibility): the recording...

My guess would be that in text mode you have to read the same 80 byte row of frame buffer memory 14 times over for the 14 scan lines of a character row, whereas in text mode you need to read a different 90-byte (720 pixels across) row of memory for each of those 14 lines. (And of course, there's...

Ok. A bit of time stepping my 8085 trainer (which surely bears some realtion to the 8080) through inc a and dec a instructions and looking at the result and flags gave me some insight: the half-carry after dec is not not a half-borrow, as the carry turns into a borrow with arithmetic adds vs...

It's been a long time since I was close to an ISA bus, and so my memory may be faulty, but wasn't the ISA bus just the system bus, with gated buffering between it and the CPU? If so, it seems to me that you just stick your ISA RAM card in it, jumper it to start after the onboard memory, and...

Maybe it's just me, but I'm feeling as if something about the labelling on that front panel looks a bit different from the original. :-)

Actually, at least on modern machines, sometimes it's better. On modern systems memory locality usually has far more effect on performance than how many instructions you're running: having to go to memory for something that's not in the cache can lose you hundreds of machine cycles, and it just...

I feel that's unlikely, but it certainly seems possible: 5.25" HD floppies were always 80-track 96 tpi as far as I'm aware, though 80-track double-density diskettes (720K) are exactly double the capacity of 40-track double-density diskettes (360K), which is probably what led to people calling...

IPA is pure alcohol and water; rubbing alcohol is adulterated with what from an industrial point of view are contaminants, which may even include oils such as castor oil. It's also generally just 70% alcohol, whereas IPA ranges from 70% to 99%. I always suggest 99%, or at least 90%, IPA for...

Thank you very much for this! That's great, and very interesting that it completed without errors. BTW can you tell me about how long it took to run on the 2 MHz 8080? I'm guessing about 2-4 minutes? The issue I've been experiencing is related to this. (This is from the _Intel MCS 8080/8085...

Thanks. On my simulator, both debug and non-debug runs I started about 18 hours ago are still running, so obviously there's something wrong with my simulator there. (Sigh.) And I've still had no luck finding someone, either here or on Retrocomputing SE, who has been able to run this on an 8080...

I think that grey areas are fine, and probably inevitable anyway. I feel that that's an utterly irrelevant point. I do not think we should be categorising things by speed because there can massive differences in speed on what's essentially the same platform. People today are running CP/M on Z80...

How long did the test take to run at 5 and 2.5 MHz? I can complete the 8080EXER test on my simulator at about 2 MHz 8080 speed on a fast machine, but I just now discovered that the Supersoft diagnostic I kicked off last night failed with a timeout after about 12 hours. I'm wondering if it...

Sigh. No. "DB-9" means "D-shell," "shell size B," 9 pins. It's just that random people (including parts vendors!) who didn't understand that "B" means a specific shell size started applying the "B" designation to "E" shell sizes. I already posted an image showing shell sizes A through E. Nobody...

Actually, it's that it's not an 8085 that interests me. The V20 is the closest thing I have to an 8080 and, at this point, it's not looking like that's going to change any time soon. I should have grabbed a TK-80 back when they were $100; now they're $400 when you can find one at all.

Which totally reminds me, I'd also like to see the results of this test on a NEC V20 or V30 in 8080 mode. (I may get around to it myself, one day, when I get around to building an SBC around one of the V20s that I have.)

Ah, ok. I've heard of it, and have a datasheet for CA80C85B (which I clearly haven't read in detail, obviously not even the title at the top :p); I just didn't know the prefix. (And, as a Canadian, "Yay Canada!" :)) I just checked it on my NEC TK-85 trainer board, which has a NEC D8085AC, and...

Can you explain how the few extra instructions on the 8085 gave a "huge" improvement in code density over the 8080? I'm not too familiar with the extra instructions, but I didn't see anything obvious in them that struck me as making a huge difference. (Not like, say, the Z80's relative branches.)

Well, that was the 8080 and so on. And in the diagram that Twospruces posted, it does not affect any of the 8080 flags. The `UI` flag there looks to me like something they might reasonably have added to work around the annoyance that `INX`/`DCX` do not update the zero flag, which is a pain when...

Ok, this one is easy. INSTRUCTION SEQUENCE WAS 040000H REGISTER f CONTAINS 00H BUT SHOULD CONTAIN 02H It's running an `INR B` instruction ($04). The two $00 bytes following it are just NOPs; one or two of those would be filled with the operand later on if the test had progressed to the two-...