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31

Per Sophie Wilson: To prove that [Steve had] designed the microarchitecture correctly, he wrote, in BBC BASIC, a model of the microarchitecture. To prove that I'd designed the architecture correctly, I wrote an interpreter for the processor's instruction set and wrote programs in it. So, well before any actual commitment to doing things, we could ...


24

This page describes one of the prototype A500s used by Paul Fellows (who led the team in charge of developing Arthur, the operating system which eventually became RISC OS). Paul Fellows himself said This machine is the one I used for development of the Operating System at Acorn. Originally these machines were hooked up to BBC micros via an umbilical into ...


11

The question statement is faulty. The approach to low power CPU design is guided by tools. Today. However, those tools did not always exist, or, when they eventually did exist, were too expensive to be used by small chip development teams who could not afford to buy time on a Cray or large mainframe needed to analyze the physical models. (Plus, the ...


7

My experience with ARM Linux was that it was typically used for embedded systems which were not expected to routinely carry an FPU of any kind, with the notable exceptions of Android phones and the Raspberry Pi. Even the initial builds of Raspbian used a softfloat build, which made no attempt to use the VFP. I was actually involved in building a hardfloat ...


6

This isn't really an answer to the question, but the comments repeatedly talk about Sophie Wilson's claim to be able to execute 100k+ ARM instructions per second. This is an impossibility on any normal 6502 and so she must have misremembered or the commenters must be misinterpreting what she said. However, it's hard to show why it is wrong in a comment. ...


5

It seems FPA itself was pretty short lived. From the ARM Linux mailing list (2004): There were only few devices which contained the FPA (ARM7500FE which is a complete system-on-chip, and FPA11 as external coprocessor to ARM3 if I remember correctly). Despite still being widely used, this instruction set is not documented in the ARM ARM. The only source for ...


5

Acorn's BBC Micro series is well known for the range of add-on processors ... ... however, other Acorn computers (the Atom, the Electron and the ABC range) did not have such an interface. So the Tube interface was not Acorn specific, but it was specific for the BBC range of computers. ... given that its predecessors ... did support them? Of course any ...


5

When a second processor (or "co-processor") was used through the BBC Micro's Tube, the Beeb's internal CPU and RAM was used for display and I/O purposes, whereas the main program code would be run on the CPU and RAM in the second processor's case. This code would include an operating system to suit the processor in question, e.g. CP/M on the Z80 second ...


4

Three contributory reasons: After the BBC Micro, Acorn were using their own processor They didn't need hardware to support other platforms Microsoft Windows hadn't cornered the market yet Using their own Processor In the 8-bit era, Acorn had used existing, off-the-shelf processors in their computers, predominantly the 6502. When designing the Acorn Proton (...


4

The original BBC Micro was designed very quickly and was subject to internal debate over its processor; the 6502 was already seven years old, and the tube appears to have been a compromise: they would ship the base machine with only a 6502 and could then experiment with the various newer processors on the market after the fact, demoting the 6502 to a mere IO ...


4

THE C64 Maxi Specs CPU: Allwinner H3 Quad-core Cortex-A7 @1.29GHz GPU: Mali400MP2 GPU @600mhz 256MB Memory 2GB FMND2G08U3J NAND Chip From here.


4

Per a forum post: THEC64 Mainboard is based on this development board Rocket64 ... ROCK64 is a credit card size 4K60P HDR Media Board Computer powered by *Rockchip RK3328 Quad-Core ARM Cortex A53 64-Bit Processor [...] Further details are in that post, and the development board it is referring to appears to be this one though the board ...


4

Well, if it's an ARM7TDMI, then it's an ARM7TDMI - what else? ARM7 - 32 Bit base architecture with T - Thumb instruction set, therefore an ARMv4T micro architecture, so no more 26 bit addressing. D - Debug extension (JTAG-Port) M - Fast multiplier I - enhanced ICE support That's what ARM sold and Nintendo bought. Or more precisely, they bought an ...


4

It is, as the citation already points out, if you use professional tools. Keep in mind that the first ARM developments should be better described as a hobbyists aproach. They wrote their own tools on BBC Mico systems using BASIC and Assembler. It wasn't until they closed in for real production, when the ARM team had to transfer their ideas into professional ...


4

[Partitial answer about how it supports FPM RAM - I still need to look up the manual for timing details] Support for (Fast) Page Mode RAM (*1) The CPU supports N and S-cycles (ARM lingo) or Non-Sequential and Sequential cycles. The first access to any memory is always an N-cycle optional followed by S-cycles. To handle this the original ARM provided a signal ...


3

The inverse perspective is to consider that ARMs were optimised for relatively slow memory (FPM DRAM), compared to contemporary pure RISC designs such as SPARC and MIPS which were designed for high frequency (40MHz or more) in "expensive" computers with caches. As the target frequency was slower, ARM could afford more complex instructions than these RISCs (...


3

When RISC technology was developed, power usage wasn't the same concern as it is today. Smartphones had not been invented yet, electricity was cheaper, Moore's Law still had plenty of life in it, and global warming was not yet on people's minds. Heat management was a concern, but reducing power draw is only one way to prevent overheating. The main goal back ...


2

While there is no evidence that Acorn released a general-purpose co-processor, they did intend to (at one point). A review of the Archimedes line, in the August 1987 issue of Personal Computer World magazine, includes the following statement: So far Acorn has announced its intention to produce the following podules: 'Floating Point', a hardware ...


2

Design is one factor determining the actual power use of your device - the other is the semiconductor process used and its tolerances and variations over the product lifecycle. Especially with whatever process is cutting edge at the time, there is no "either it doesnt work or it works and consumes exactly n watts of power in a given state" - more of a ...


1

I believe there are no differences whatsoever; it's a little hand-wavey but e.g. the GBATEK document (in that link reformatted into NoCash style) appears to describe an ordinary ARM7TDMI.


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