Viewing profile — Dr_Jefyll

> 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 tha…

> 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…

"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 r…

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. I…

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 print…

>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 …

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 both…

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],…

>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 pre…

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 …

> 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.…

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 goo…

>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 con…

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=1246…

Thanks, JdeBP, for remembering the KK :-)

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 …

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://laughtonelect…

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 …

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-m…

Yup. And the triple 8080's contributed a lot to the character of the thing, too.

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…

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 off…

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 th…

> 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: …