Dr_Jefyll

6 ms·

1.
by Dr_Jefyll 5mo ago
> I find [8086 segmentation] enormously preferable to the 65816’s bank system. The primary advantages are twofold: segment overrides may be provided to any pointer, which means that it is less necessary to juggle segment values the way i
2.
by Dr_Jefyll 8mo ago
> when an ESCAPE instruction is encountered, the 8086 processor starts executing the instruction, even though it is intended for the 8087. The 8086 computes the memory address that the instruction references and reads that memory address
3.
by Dr_Jefyll 2y ago
"One Bit Computing at 60 Hz" describes a one-bit design of my own that folks have repeatedly posted to HN. It's notable for NOT using the MC14500... (and for puzzling some of the readers!) The original 2019 post by Garbage [1
4.
by Dr_Jefyll 3y ago
Clever and interesting! But not new. FWIW, I remember repairing a PA or musical instrument amplifier in the 1990's whose power transformer featured this type of core and bobbins. Its novel appearance and intriguing construction attract
5.
by Dr_Jefyll 4y ago
Probably the second-best fun I ever had was reverse engineering a discrete-TTL processor and the firmware written for it. These were embedded in some Xerox Diablo daisy-wheel printers dating from the latter half of the 20th Century. And th
6.
by Dr_Jefyll 4y ago
>The MC14500B has an unusual architecture, making it more of a building block than a complete microprocessor. [... It] requires multiple external chips to make it usable. Love the articles you've been posting, Ken! And yes the MC145
7.
by Dr_Jefyll 5y ago
Picking up on the "three at once" theme, the 1-bit computer I built in the 1980's has an instruction that does three things. The computer only has one instruction, so I didn't bother to give the instruction a name. Bu
8.
by Dr_Jefyll 6y ago
Great choice of subject matter, as usual, Ken! May I direct your attention to a one-bit machine [1] that's already something of a favorite on HN, posted for discussion in 2014 [2], 2016 [3] and 2019 [4]. "This is not a Motorola MC
9.
by Dr_Jefyll 6y ago
>this only tells us about the performance of this particular FORTH engine Yes, exactly. Whatever its other qualities may be, I suspect this particular Forth has overlooked some pretty obvious low hanging fruit, performance-wise. In this[
10.
by Dr_Jefyll 6y ago
Rather than buying suction cups (for which I would subsequently have had no further use), I managed very nicely by using just a couple of strips of packing tape. Each strip formed a "handle" -- one on each side of the screen, sam
11.
by Dr_Jefyll 7y ago
> it might be helpful to have an example or two Apologies. The original source code from the early 1980's is stored on a non-DOS floppy. Maybe someday I'll retrieve and publish it. But meanwhile here's a taste: One of the
12.
by Dr_Jefyll 7y ago
One of us must be drinking de-caff by mistake! :D When I use the search at the bottom it "corrects" the spelling, not even bothering to remark on what it did. Adding quotes was good suggestion, but now there are 0 search results.
13.
by Dr_Jefyll 7y ago
>I think I would get a headache "programming" it One-bit creator here. I'm surprised by how often people make comments like this. Is it the dual jump destinations which seem so confusing? All you need is to ignore one of
14.
by Dr_Jefyll 8y ago
Thanks for posting, Tomte. This is a project that's been discussed on HN on the past. -- Jeff https://news.ycombinator.com/item?id=7616831 https://news.ycombinator.com/item?id=12469790
15.
by Dr_Jefyll 8y ago
Thanks, JdeBP, for remembering the KK :-)
16.
by Dr_Jefyll 9y ago
I was delighted at being able to cite an independent source saying such a thing was possible! In the 2016 HN thread "Strange bug workarounds" I posted a much gnarlier problem (and oddball solution): https://news.ycombi
17.
by Dr_Jefyll 9y ago
Glad to see confirmation of using a rubber band to fix an IBM mainframe. Been there done that, but the story is so loony I wondered if anyone would believe me. http://laughtonelectronics.com/oldsite/comm_mfg/commer
18.
by Dr_Jefyll 9y ago
Back in the day (late 1980's) there was ample motivation as I had no knowledge of or access to the 65816. Programmable logic has changed the landscape since then -- and btw I have whimsically contemplated a modern re-issue of the KK.
19.
by Dr_Jefyll 9y ago
Thanks for posting, ingve (and 0x12). 0x12's HN thread [1] about my project included the following TLDR: "Guy expands 6502 to 16M address space by intercepting the databus and re-mapping unused opcodes and clever use of the spurio
20.
by Dr_Jefyll 10y ago
Yup. And the triple 8080's contributed a lot to the character of the thing, too.
21.
by Dr_Jefyll 10y ago
In the 1980's I had a client that manufactured cheques, and the typesetting was done by four or five "Wescode 1420M" systems. These technological marvels used an 8" floppy drive to input order data -- the customer name,
22.
by Dr_Jefyll 10y ago
A prior HN thread [1] about this was entitled, "The KimKlone: a radical 6502 redesign" [1] https://news.ycombinator.com/item?id=3070169 The poster, 0x12, had this to summary to offer: "Guy expands 6502 to 16M
23.
by Dr_Jefyll 10y ago
Thanks for your interest in my projects, 6502nerdface. You've linked to the "chatty" KK article but there's kinduva TLDR version, which folks may prefer, here [1]. In particular the block diagram covers a lot of ground.
24.
by Dr_Jefyll 10y ago
> autodidact != crank This. Unless you consider Charles Darwin, Oliver Heaviside, James Watt and Thomas Edison cranks. And that's just the tip of the iceberg, as you can see here: https://en.wikipedia.org/wiki/L
25.
by Dr_Jefyll 11y ago
>Eight 74172s provide eight 16-bit registers in a three-port register file. This file may simultaneously write one register ("A"), read a second ("B"), and read or write a third ("C"). In a single clock cycl
26.
by Dr_Jefyll 11y ago
Thank you for posting. A PCB would be fun but I'd be inclined to do a shrink, moving away from all the jelly-bean logic. I'm pretty sure a KimKlone clone (!) could be done with just a 128 macrocell CPLD, a '574 and the 2 uC
27.
by Dr_Jefyll 11y ago
I was in my twenties, I was hugely turned on by the electronics I was learning, and I was bursting with creativity! There's a little bit of Back Story explained here, especially the "my KIM" section at the bottom of the page.
28.
by Dr_Jefyll 11y ago
Right -- not a 65c816. There's a summary and block diagram here: http://laughtonelectronics.com/Arcana/KimKlone/Kimklone_shor... I'm the builder! :o) -- Jeff
29.
by Dr_Jefyll 15y ago
Sorry about the TLDR situation; it's on my list to revise the article by prepending an abstract. BTW suggestions and questions about the article are welcome. @mjhall - you're quite right; the strange, phantom 65c02 operations dramatically e
30.
by Dr_Jefyll 15y ago
Thank you, 0x12 and all of you, for your interest in my quirky creation. Naturally I follow modern FPGA technology avidly, but I guess it's obvious that my project predates that sort of thing. 2901 style Bit-Slice components were the wonder

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