jecel

10 ms·

61.
by jecel 2y ago
Here the `int` is being used in place of `char *`, not `char`. And yes, the PDP-11 did have byte addressing while the PDP-7 on which Unix was originally created was a word addressed machine.
62.
by jecel 2y ago
An interesting option is rod logic, which is the mechanical equivalent to a PLA (programmable logic array). https://www.jamiekawabatarobotics.com/?p=40
63.
by jecel 2y ago
The first ATMega, the ATMega603, needed an external device to write to its Flash program memory. The following models removed this restriction.
64.
by jecel 2y ago
"No-one would claim that a modern Harvard Architecture computer with its program stored in ROM isn’t a stored-program computer. So does ENIAC take the prize from Baby as the first electronic stored-program computer?" I do actually
65.
by jecel 2y ago
The Apple I had a single 256 byte bipolar PROM for its WozMon debugger. Though the Apple II used ROMs (EPROMS were popular in clones) the expansion cards still were supposed to use tiny PROMs for their drivers (in the case of the disk contr
66.
by jecel 2y ago
I did a 16 bit processor that is compatible with RISC-V at the assembly language level but has its own binary encoding: https://github.com/jeceljr/digitalCPUzoo/tree/main/drv16 It is meant as a helper pr
67.
by jecel 2y ago
Just expanding it from 8 to 16 bits makes it practical, if still awkward. I implemented the 2048 game on that, for example. https://github.com/jeceljr/digitalCPUzoo/tree/main/MCPU
68.
by jecel 2y ago
https://spectrum.ieee.org/nanoimprint-lithography
69.
by jecel 2y ago
> + 2 others that I honestly have no idea what they do The original RV32I and RV64I required some control registers for high frequency counters and instruction counters. You also needed the instructions to access these registers. This pr
70.
by jecel 2y ago
Dataflow processors have not been forgotten - there is one inside every high end CPU core. The code in main memory in the form of conventional x86 or ARM machine language gets translated first into "micro ops" in the decoder and t
71.
by jecel 2y ago
In the late 1990s there was a fun geek webcomic called "After Y2K" that imagined a very different world caused by a huge disaster. I didn't expect anything other than what actually happened, but a lot of people actually belie
72.
by jecel 2y ago
"The terminology of calling computer parts "organs" is gone now, but the "Control" here describes what we now commonly refer to as CPU." Actually, what was described is currently called the "Control Unit&q
73.
by jecel 2y ago
It is possible to build single cycle Harvard computers but not von Neumann ones. So a course on computer architecture using, for example, RISC-V as a concrete example might start out showing a Harvard RISC-V with a single cycle implementati
74.
by jecel 2y ago
Herman Goldstine made the decision to distribute the report. Though Eckert and Mauchly liked to think they came up with the idea before von Neumann came along and that he got the idea from them, it is very hard to know if that is true. Kurt
75.
by jecel 2y ago
The RISC-V creators were aware of the issues when they designed the C extension with 16 bit instructions to be able to compete with ARM's Thumb. So the bottom two bits of an instruction are enough to distinguish between 16 bit and 32 b
76.
by jecel 2y ago
It is better to say RVC is almost never present without the full-size 4 byte instructions since we have one counter example: https://github.com/gsmecher/minimax This is an experimental rather than practical design that
77.
by jecel 2y ago
While Trilogy ran into technical problems, Sinclair's Anamartic actually delivered working products: https://www.computinghistory.org.uk/det/3043/Anamartic-Wafer... The long term plan was something not that d
78.
by jecel 2y ago
Note that the country's full name has been "República Federativa do Brasil" only since 1968. Between 1889 and 1967 it was "Estados Unidos do Brasil". https://pt.wikipedia.org/wiki/Estados_Unidos
79.
by jecel 2y ago
A very nice book is "Designing Video Game Hardware in Verilog" by Steven Hugg and is part of a series of books that is supported by http://8bitworkshop.com/ I am writing a book somewhat similar to this (currently
80.
by jecel 2y ago
One additional obstacle for modern audiences is that the TV sets themselves are computers running software. They take a MPEG-2 or MPEG-4 file coming in some network port and send it to some mixed parallel/serial interface to a LCD or s
81.
by jecel 2y ago
This reminds me of the "Kansas" environment in the Self programming language. Here is a video about it from Sun in 1995: https://www.youtube.com/watch?v=Ox5P7QyL774 More interesting search features were added afte
82.
by jecel 2y ago
I am more familiar with the F18A predecessors, such as the F21, than with this design. So it is quite possible that it is a proper asynchronous processor even if the older ones were not. I am biased by some confusion I observed about the F2
83.
by jecel 2y ago
It is far easier to join two asynchronous blocks into a larger system than two synchronous blocks. So place and route would be less critical.
84.
by jecel 2y ago
If I understood correctly, the GreenArray chips don't have a clock but each individual core does via a local ring oscillator. So it might run at a different speed than its neighbors and the communication system handles that. A more fam
85.
by jecel 2y ago
The comments show a lot of confusion about what Tesler invented. Other industries did indeed use cut/copy/paste and older editors had ways to do these functions. But the cursor in these editors normally indicated a character. Larr
86.
by jecel 2y ago
The 74181 has four signals to select the operation (S0 to S3) but also two modifiers. M=1 selects logic functions and M=0 selects math functions (which will be slightly different depending on the value of carry in). So there are 3x16 = 48 p
87.
by jecel 2y ago
Nearly all current computers address bytes, but in the past we had many computers that addressed words instead as well as processors like the Texas Instruments 34010 that did address bits.
88.
by jecel 2y ago
"Computer architecture" is used in several different ways and that can lead to some very confusing conversations. Your proposed stack has some of this confusion. Some alternative terms might help: "computational model":
89.
by jecel 2y ago
Wouldn't that be the 34010?
90.
by jecel 2y ago
One difference between the standard cells in the article and the current ones is that the routing channels have been eliminated thanks to the many metal layers we now have. Back then we couldn't really afford to have metal cross the Vd

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