jecel

5 ms·

1.
by jecel 5d ago
The first line of https://en.wikipedia.org/wiki/Logo_(programming_language) is "Logo is an educational programming language, designed in 1967 by Wally Feurzeig, Seymour Papert, and Cynthia Solomon." so you ar
2.
by jecel 3mo ago
The simplest processors use one clock per instruction with a Harvard architecture. This allows their control unit to be a combinational circuit instead of a Finite State Machine (and depending on how your memories work you might even avoid
3.
by jecel 4mo ago
I think there were actually 68000 transistor positions. In the ROMs and PLAs not every potential transistor is populated but the missing ones were counted as well. But the number of actual transistors is only slightly smaller so it doesn&#x
4.
by jecel 7mo ago
One chip that could be used as a memory mapper for the 9900 (but wasn't in the TI99/4A) was the 74LS670, which was used in the IBM 5150 PC to allow the 8237 DMA chip to access more than 64KB (a limit that wasn't a problem whe
5.
by jecel 7mo ago
Note that RISC5 [1], a project created as a target for Wirth's Oberon compilers, is a different project from RISC-V [2], a project created at Berkeley which became what is currently the most popular open source ISA. [1] https:/&#
6.
by jecel 7mo ago
We were stuck with 33MHz PCBs for a long time as people kept trying and failing to get 50MHz PCBs to work. Then Intel came out with the 486DX2 which allowed you to run a 50MHz processor with an external 25MHz bus (so a 25MHz PCB) and we sta
7.
by jecel 8mo ago
The naming of processor sizes is the subject of debate. I call a "pure 8 bit processor" one that has 8 bits for both data and addresses. Like the Kenbak-1. But these are so rare and educational rather than practical that it is ver
8.
In Memoriam: Remembering Mike Flynn(computer.org)
4 points by jecel 8mo ago|2 comments
9.
by jecel 8mo ago
Michael J. Flynn, best known in the computing world for his taxonomy of parallel computing (SISD, SIMD, MISD and MIMD), passed away on December 24, 2025
10.
by jecel 8mo ago
Two years after this booklet, the CRT memory it describes was replaced by core memory (becoming the first computer to use that technology).
11.
by jecel 8mo ago
Most people are not aware that after the failure of the PS/2 attempt to control the PC market, IBM tried a third time using 7 patents it had for the PC AT (they didn't have any on the original PC or the XT). In the first half of t
12.
by jecel 9mo ago
Here is a one hour talk Stewart gave at the 2016 VCF East (Vintage Computer Festival): https://www.youtube.com/watch?v=Ncnje4DdRxE He mentions that the first year it was a live program and they didn't have the resource
13.
by jecel 9mo ago
QNX was my operating system from 1985 to 1988. I also studied it in 2000 for a project that ended up getting cancelled. Initially the actual implementation didn't match the conceptual framework, but by version 1.2 they had really clean
14.
by jecel 9mo ago
One issue he mentioned is still true today in Brazil's universities: while in theory you can ask to transfer from one course to another, in practice you have to drop out of your current school and take the entrance exam for the other o
15.
by jecel 9mo ago
Actually, the 68000 had one full (all operations) 16 bit ALU and two more simple (add/subtract, so AU might be a better name) 16 bit ALUs so in the best case it could crunch 48 bits per clock cycle. The 8086 had one full 16 bit ALU and
16.
by jecel 9mo ago
The 68000 actually had both microcode and nanocode, so it was even further from hardwired control logic than the 8086. In terms of performance the 68000 was slightly faster than the 286 and way faster than the 8088 (I never used an 8086 mac
17.
by jecel 9mo ago
They should say on this page that this project has ended. There are some spinoffs people interested in this can look into: https://tinytapeout.com/ https://wafer.space/ https://chipfoundry.io&#x2
18.
by jecel 10mo ago
The Indy 500 was actually part of the official Formula 1 calendar from 1950 to 1960, though the two series diverged after that. Some Indy features (refueling, changing tires even if they didn't have a puncture, safety cars) got adopted
19.
by jecel 10mo ago
Though a problem, as you point out, it still happened. The 6800 based SWTPC was followed by 6809 machines what need to have all their software reassembled. On the other side of the cpu wars, all those 8080 machines moving on the Z80s got to
20.
by jecel 10mo ago
Thank you for correcting me. I don't know where I heard the story I mentioned.
21.
by jecel 10mo ago
My own memory of the events (which might be very wrong) was that a new vice-president of IBM semiconductors decided to drop bulk CMOS and focus exclusively on SOI (Silicon On Insulator). That suddenly left Transmeta without chips to sell. T
22.
by jecel 11mo ago
The VM in Slang had been previously published as part of the "blue book" (now that is what I call open source!) some 14 years before, and as the paper you linked to mentioned, Mario Wolczko at the University of Manchester had type
23.
by jecel 11mo ago
If we label the combinations of the seen and scanned bits as: 00: white 10: gray 11: black then we cam describe it as a very cool variation of the tri-color gc algorithm. https://en.wikipedia.org/wiki/Tracing_garbage_co
24.
by jecel 11mo ago
> Finally, a programing job that AI won't be able to replace. Well, at the recent VCF (vintage computer festival) Midwest they showed a robot using the Altair's front panel to toggle in a game: https://techav.net&#x2
25.
by jecel 11mo ago
Exactly, but the text has the same instruction sequence twice and the parent correctly indicated that the first copy should have used "lui" to illustrate the problem you mentioned and the second copy does use "auipc" to
26.
by jecel 11mo ago
The problem with Self in the 1990s wasn't the lack of sources (I just checked the 1994 Self 4.0 sources and the license looks like the typical BSD one) but the fact that the binaries only ran on Sparc workstations and not the computers
27.
by jecel 11mo ago
The early microcomputer market had three kinds of companies: - those with organic growth, where the sales of products financed the development of new products: MITS, IMSAI, Sphere, Ohio Scientific, SWTPC, Cromemco, Processor Technology, etc
28.
by jecel 11mo ago
You are correct about the US in relation to trademarks. The situation there is rather complex, with it being possible for people to just add TM to their texts and ask other people to do the same and it is considered legally binding. They ca
29.
by jecel 11mo ago
They hesitated a bit on continuing to release it as open source when they moved from Stanford to Sun (I should actually say Sun's lawyers hesitated) but then went ahead and released Self 2.0 sources (Self 1.0 and 1.1 had been open sour
30.
by jecel 11mo ago
They are completely different designs, but the name is inspired by the same source: the Mill component in Charles Babbage's Analytical Engine.

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