> From: Peter Ekstrom <epekstrom(a)gmail.com>
>
> I am tinkering with some C-code where I am working on something that
> can process some microcode. The microcode is from a DG MV/10000
> machine and while working on it, I noticed it is in little-endian.
> That's simple enough to work around but that had me wondering, why do
> we have big and little endianness? What is the benefit of storing the
> low-order byte first? Or is that simply just an arbitrary decision
> made by some hardware manufacturers?
Mostly because hardware support for dividing a word into smaller chunks
(and addressing them individually) was something manufacturers added at
different times, on their own initiative, and there was no agreed-upon
way to do it. And since there are two obvious ways to turn a sequence
of X Y-bit chunks into a word of X * Y bits and neither one is exactly
"wrong," it ended up being a crapshoot as to whether manufacturers
would do it the one way, or the other.
(...or do something demented instead, like the PDP-11's "middle-endian"
approach to 32-bit values...)
And most of the debate probably came down to matters of taste; big-
endian is how we write things on paper, so it seems "natural" to most
people, while little-endian means that byte offset matches place value
(i.e. byte 0's value is multiplied by (256 ^ 0) = 1, byte 1's value by
(256 ^ 1) = 256, etc.,) so it seems "natural" to math types.
That said - and I have no idea whether this actually influenced
anyone's decision for any system anywhere ever - one hard advantage of
little-endian representation is that, if your CPU does arithmetic in
serial fashion, you don't have to "walk backwards" to do it in the
correct sequence.
> On Aug 15, 2024, at 1:27 PM, Michael Thompson <michael.99.thompson(a)gmail.com> wrote:
>
> Danny Cohen, author of "On holy wars and a plea for peace", on the left and me in the white shirt, taken in 2003.
>
> MIPS CPUs can be configured by the hardware to run in either big-endian or little-endian mode.
Indeed, though depending on the vendor, support for one of the modes may be marginal.
I remember evaluating the Raza (now Broadcom) XLR processor when it first came out. Was told it supported little endian, which we needed. Tried to configure the eval unit in little endian mode -- dead as a doornail.
Asked the rep. Answer: "well, the *hardware* is designed to support it, but the power on boot configuration code is big endian only". Oh. Ended up spending a month or two converting fun stuff like DDR timing tuning loops to little endian. It did eventually work, but no thanks to the people selling the device...
paul
Hi,
in my stash of IC's Ive found a small box containing some Harris TTL
Proms 75xx and 76xx.
Interestingly the print is up right when the pin 1 is on the left side.
I think they are pulled somewhere, otherwise they look linke new..even
the pins aren't strongly rectangular..they are spread a little to the
outside.
I don't know what todo with them. If someone recognizes the numbers
printed on them and think that he want those chips, I'll ship them
worldwide for just the shipping costs.
Drop me a mail, otherwise the will enter the dumpster in a week.
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583
info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741
All –
There may be some overlap between cctalk and other lists, but I’m working on some Lomas reproduction boards, the first being the Color Magic. I’ve made two prototypes, neither of which works with the Lomas 186 board I have. It’s a very long story (working on this for more than a year on-and-off), but I borrowed a working set of boards to assist with the reproduction so I can test from a known-working configuration. What I’m looking for is a clean scan of the schematics. There are two versions floating around, neither of which is particularly clean, so I’m looking for a clean copy so I can eliminate as many points of difference as possible. If anyone can assist with this, I’d appreciate it.
Thanks!
Rich
--
Rich Cini
http://cini.classiccmp.org
Hi there,Haven't had much time for vintage computers due to my job dealing with new ones, but the odd evening I have been working on PCB replica projects.One of them is for the MAI Jolt. I recently picked up alsome NOS 6530-004s, and thought it'd be a fun replica to try. I have completed the backside in KiCAD by tracing photos of the board i found online, but unfortunately the only decent photo I was able to find of the top side has components installed, and I am not good with electrical guesswork.I don't know exactly how the JOLT was originally sold (kit? Assembled?) but I'm thinking if MAI were like most pioneers then they almost certainly would have provided a schematic to end users for modifications and troubleshooting.Does anyone know if such a thing exists? I've been searching the usual places without success.Or if anyone out there has a bare board (I know, I know heh).. and wouldn't mind sending a photo or two..BradSent from my Galaxy
From time to time I have seen people looking for flyback transformers on the list. I just came across a resource that may (or may not) be useful for anyone looking for one. Hope this is of use to someone.
https://www.technotronic-dimensions.com/sitemap.htm
Will
Grownups never understand anything by themselves and it is tiresome for children to be always and forever explaining things to them,
Antoine de Saint-Exupery in The Little Prince
> From: Adrian Godwin <artgodwin(a)gmail.com>
>
> i think it was strongly disliked by many non-technical users because
> it was the first one where MS tried to lock down some admin
> functions, forcing the users to confirm or enter an admin password to
> continue. This isn't necessarily bad but it was rather hamfisted and
> disliked.
This, 100%. On top of the usual "chews up more memory for not that much
more functionality" issue that's always the case, the initial release
of UAC was *spectacularly* braindead, to the point where the simplest
way to make Vista usable was to disable it entirely - and once that
habit was ingrained in users, they persisted on down the line, even
well into Win10's lifetime. Windows really did need improved security/
permissions features, but their rollout was such a bungle that we ended
up with a world where millions of people ran *less* secure by choice,
because it just wasn't worth the pain.
