Recent content by Eudimorphodon

This "unsourced claim" seems backwards, because EEMS came before EMS 4.0. EEMS was a private not-quite-standard put together specifically by AST, Quadram, and Ashton-Tate, which added the capability to swap memory pages anywhere under the 1MB mark (assuming it didn't conflict with wired memory...

Yeah. One minor correction to my read-through of it, the memory in the MMU isn't 24 bits wide, it's 12; it has to make two separate fetches to grab the SOR and SLR data. Confirmed by looking at the schematic. (So it's "1.5K" total RAM, not 3K, which I should have caught.) Wouldn't surprise me if...

Or we could just do something more positive, like retreat into a corner and silently weep for half an hour over what humanity has become.

Maybe this new Commodore will resurrect the Commodore LCD and be able to convince prison authorities that a computer *this* dumb is immune from being used as a covert dark web terminal or whatever. It had less RAM than most of Swintec's typewriters, even the prison varieties.

Yeah, the MAX232’s whole deal is the integrated charge pump voltage generators. Power conversion aside, strictly speaking the MAX232 is the rough equivalent of *half* of a 75188 and *half* of a 75189. (The ‘188 is a quad transmitter, the ‘189 is a quad receiver, the MAX232 is two of each.) This...

My bad, I noticed after the edit window closed that I accidentally posted the same link twice. Here’s the patent document: https://archive.org/details/bitsavers_applelisahmupatent_588120/page/7/mode/2up The confusing part of the patent document is it seems to go out of the way in the diagrams...

So… maybe? This document here: http://www.bitsavers.org/pdf/apple/lisa/development_history/memos/Kato_-_Lisa_Hardware_19851012.pdf Has a description of the MMU which… makes the description in the patent document...

Yeah. I was looking at the patent docs for the Lisa MMU, and while it’s a lot “fancier” than the TRS-80’s (four hardware contexts instead of two, write protection bits so it can split a segment into R/W and read-only sections, etc) it looks ultimately it's just a base/range segmentation MMU that...

I have a tube of those MT88xx (I think mine are 8812s, not 8816s) that I keep failing to find time to use to build a converter like that, except for a USB keyboard. I'd like to be able to use those cheap tacky LED gamer keyboards with the Cherry knockoffs.

FWIW, segment-based "MMUs" were dirt common in 68000 machines intended to run Xenix; in their simplest case they were essentially just an adder that let each process use absolute addressing based on an offset of zero and a bounds register that faulted if the program tried to use more memory than...

I think what the world really needs is a reboot of the old People's Computer Company newsletter. Frankly I'd much rather have (and contribute to a 'Zine) that looks like this: Than yet another vector for superficially-slickly-produced but completely vapid AI generated slop content. I have...

I mentioned this offhandedly in one of the other threads because it struck me just how lame it was. I’m sorry, but this self-entitled whining about people being insufficiently impressed at your “hard work” dictating to the copyright theft machine is so pathetic that so far as I’m concerned this...

I’m getting more and more convinced that this hardware that was teased is just going to be one of those execrable MyRetroComputer things, with a Founders Edition or similar sticker on it. Maybe it’ll even come with a “stock certificate”. Ugh. I love Bil Herd’s rascally stories about old...

The “incoming” LVC ‘245s shift the TTL level signals from the bus down to 3.3v for the memory bus, and the “outgoing” ‘245s (which would be some flavor of LS/F/HCT/whatever) would drive “according to Hoyle” TTL level out. And like I already said, I think this is probably completely pointless...

In all fairness an LCD like the Model 100's was still basically sci-fi tech in 1979. (Crazy how fast that changed.) That's the year Microvision, with its whopping 16x16 pixel display, came out.