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://riskfive.com/RISC5_overview.htm

[2] https://riscv.org/

It is funny that RISC-V International moved to Switzerland in 2020 so now both projects can be found in the same place.

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 started moving forward again, though we did eventually get PCBs to go much faster as well.

The Transputers (mentioned in other comments) had already decoupled the core speed from the bus speed and Chuck Moore got a patent for doing this in his second Forth processor[1], which patent trolls later used to extract money from Intel and others (a little of which went to Chuck and allowed him to design a few more generations of Forth processors).

[1] https://en.wikipedia.org/wiki/Ignite_(microprocessor)

> We were stuck with 33MHz PCBs for a long time as people kept trying and failing to get 50MHz PCBs to work.

What is the current best symbol rates we get on PCB traces? I know we’ve been multiplexing a lot of channels using the same tricks we used with modems to get above 9600bps on POTS.

How conservative of a lower bound would next-gen PCI-e give?

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 very reasonable to call hybrid 8 bit / 16 bit processors just "8 bit".

This use of sloppy terms shouldn't make us forget that they are using an address extension trick, just like all those 16 bit processors that wanted to go beyond 64KB (for byte addressed such as the PDP-11, Z8000 or 8086) or 128KB (for word addressed, like the Xerox Alto's modified Data General Nova model).

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

Two years after this booklet, the CRT memory it describes was replaced by core memory (becoming the first computer to use that technology).

Indeed, for those interested, the Whirlwind archives include a lot of details on Jay Forrester's core memory, as well.

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 the 1990s they went after the chipset makers (mostly in Japan at that time) and in the second half of the 1990s they went after the PC makers themselves all around the world. The would threaten to sue for all machines made up to that point unless they licensed not only the 7 AT patents (which would expire in 2001) but also a bunch of other unrelated patents that were much newer. As far as I know everybody signed the deal, which meant that IBM could make money without actually making any PCs themselves.

This is true, but the patents were all RAND-licensed, so the press reported that IBM made about $5 per PC. Which isn't nothing, but IBM had no ability to restrict PCs market segments (like they had with Microchannel). So we soon saw "commodity" PC servers and even midrange systems, stealing IBM's bread+butter.

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 resources to record them, so they are not available.

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 cleaned things up.

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 one. And then you waste a lot of time trying to get your grades for the courses you have already taken recognized as equivalent so you don't have to start from scratch.

For him to move from math to electrical engineering to physics in Brazil would mean going through this twice. This might make him take some 7 or 8 years to graduate.

I guess this inflexibility makes things easier for the administrators. They know they will have 25 students in the statistics class in 2028 and so know how many teachers to hire to handle that.

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 one simple 16 bit ALU (the ancestor of todays AGUs - address generator units).