Questions tagged [performance]

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Fastest 8-bit microprocessor for multiply-accumulate?

I'm wanting to identify which 8-bit microprocessor would have the best performance for a multiply-accumulate operation. By "operation", I mean the minimal implementation for 16-bit operands ...
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5 votes
1 answer
643 views

Who were the market for those "speed up your computer" shareware applications back in the day? [closed]

In the Swedish computer magazine PC Hemma ("Home PC") from February 1997 (p. 68), they included a floppy disk with shareware programs related to "trimming your PC", as well as a ...
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7 votes
1 answer
558 views

Hardware for higher resolution VESA modes

What computer hardware was needed to run something like Duke Nukem 3D smoothly at the 640x480 or 800x600 VESA modes at the time (1996-1997)? I was wondering if this was possible with contemporary ...
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23 votes
3 answers
6k views

Why might Quake run slowly on a modern PC?

I noticed back in the DOS gaming era that DOS games ran slowly in hi-res modes. I was surprised to discover that this could be true on a modern machine. I booted a 2017 i5 7200u (I think) laptop into ...
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11 votes
2 answers
2k views

The march of progress before microchips

Throughout the 1980s and 1990s, computer power seemed to increase so drastically that pretty much any computer you could own rapidly became obsolete. Such were the strides in available power and ...
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33 votes
4 answers
5k views

Why was manual branch suggestion abandoned?

Once pipelined CPUs became common, a common issue arrived as a result of taking the wrong branch of a conditional jump, and thus needing to flush the pipeline. As a result branch prediction mechanisms ...
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36 votes
17 answers
8k views

How fast were BASIC interpreters in the 80s? (Is this optimization for speed really necessary?)

I have a client who wants me to analyze a BASIC program from Umberto Eco's Foucault's Pendulum. I have never written a line of BASIC in my life as I was born in 1995 and started programming around ...
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1 vote
1 answer
170 views

Did the computing power of end users increase at a steady pace over the years? [closed]

Does the computing power of the average people in the household increase at a steady pace or has it wax and waned over the years? Are there some eras of computers where computing power grew faster ...
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6 votes
3 answers
2k views

What is the MOS 6502 doing on each cycle of an instruction?

So, first off, I am kind of a noob with emulators and the 6502. Summarise the problem If we for example take the instruction ADC Immediate ($69) which adds the accumulator to an immediate value and ...
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18 votes
1 answer
1k views

How did the Nova 1200 divide so quickly?

According to https://en.wikipedia.org/wiki/Data_General_Nova The Nova 1200 executed core memory access instructions (LDA and STA) in 2.55 microseconds (μs). Use of read-only memory saved 0.4 μs. ...
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8 votes
1 answer
1k views

Why was the Nintendo 64 bad at textures?

The Nintendo 64 had a reputation for being great at drawing triangles, but not so good at texturing them, so that many games fell back on heavy use of untextured (though Gouraud shaded) triangles, ...
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4 votes
2 answers
714 views

How fast was Rambus compared to regular EDO RAM?

The Nintendo 64 used Rambus RDRAM. This was an unusual choice, e.g. the PlayStation used regular EDO RAM which I gather most consoles and computers did at the time. As I understand it, Nintendo chose ...
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14 votes
1 answer
3k views

Why was the 1541 so slow?

The Commodore 1541 floppy disk drive, sold for use with the 64, was notoriously slow for historical and technical reasons: Marketing insisted on compatibility with the 1540, the floppy drive sold ...
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2 votes
2 answers
434 views

How fast did the ARM-1 access memory?

The ARM-1, an early 32-bit RISC CPU, was used in the Acorn Archimedes computers, released in 1987. Its rated speed was one 32-bit instruction per cycle at 8 MHz. Typical RAM chips at that time would ...
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12 votes
6 answers
6k views

Did any RISC CPU ever take more than one clock cycle per instruction?

Classic RISC CPUs like ARM and MIPS basically offer the trade-off: simple instruction set, but instructions execute in one cycle for good overall performance. (It gets more complicated in later times, ...
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3 votes
1 answer
196 views

How long would a 41256 take to do 4 accesses in fast page mode?

I have been surprised at how little use eighties computers made of fast page mode access to RAM. (A notable exception being the Sinclair Spectrum, which used it to get the necessary bandwidth to video ...
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10 votes
2 answers
1k views

What PC graphics tech outperformed Sega Dreamcast in 1999?

The Sega Dreamcast was released in 1999 (1998 in Japan) at just the time that the competition for 3D graphics on PCs was intensifying. It's my assumption that a high-end 1999 Pentium II PC with 3Dfx ...
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7 votes
1 answer
578 views

Why is ZX80 much faster than Spectrum on Rugg/Feldman benchmarks?

If you look at the results of the Rugg/Feldman benchmarks, shown in this Wiki entry, you'll see that Sinclair ZX80 is much faster than Sinclair Spectrum on all tests despite the fact that both ...
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18 votes
6 answers
6k views

How slow was the 6502 BASIC compared to Assembly

Imagine a modern computer, where let's say Python is a high level programming language and needs to be interpreted in order to execute a piece of code. You could write some code in C, compile it, ...
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2 votes
1 answer
277 views

How to load into FAST RAM on Apple IIgs?

The Apple IIgs (last, ROM03 version) came with 128K of standard RAM and 1M of FAST RAM. The distinguishing characteristic of the FAST RAM is that code running from there can run at 2.8 MHz instead of ...
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8 votes
4 answers
785 views

Does fast page mode apply to ROM?

Starting with the 4116, RAM chips from the late seventies supported fast page mode, where if you were reading nearby – particularly, successive – words, you didn't need to supply both row and column ...
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8 votes
1 answer
613 views

How can floating point addition be so slow on a BESM-6?

In the BESM-6 technical manuals — for example, in the ALU description, page 4 — there is a table specifying min/max/average instruction latencies in clock cycles (the last 3 columns; the ...
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14 votes
4 answers
3k views

For fast scrolling DOS games, when was Mode13h preferred over Mode X?

Back in the DOS days of gaming (more specifically, 80286 - 80486 era), developers typically needed to choose between using the chunky and easier Mode 13h or the more complex "Mode X" that provided ...
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10 votes
1 answer
469 views

Which pre-IEEE computers had a single precision FPU and implemented double precision floats in software?

Before the formats of floating point numbers have been standardized in IEEE 754 in 1985, different vendors had used many different floating point formats, some of them listed on the Data Format and ...
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4 votes
2 answers
425 views

FCC RF limits and wire transmission speeds

As I understand it, in the early days of personal computers, strict FCC limits on RF emissions, were a factor limiting the speed at which data could be transmitted over wires, but I'm trying to ...
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2 votes
1 answer
555 views

File system performance and the Unix API

A 1994 book called 'The Design and Implementation of a Log-structured file system' contains the claim "We have implemented a prototype log-structured file system called Sprite LFS; it outperforms ...
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7 votes
4 answers
3k views

Amiga memory bandwidth

Looking at a timing diagram for the various kinds of memory access occurring on the Amiga http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node02D4.html it seems to be saying that video ...
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1 vote
1 answer
658 views

How adequate would 48-bit floating point be? [closed]

Though power of 2 word sizes look in hindsight like a natural consensus, historical computers used quite a wide variety, including but not limited to 9, 18, 36, 12, 24 and 60 bits. Power-of-2 ...
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  • 48.8k
6 votes
2 answers
249 views

Can fast page mode depend on the first data retrieved?

As early as the seventies, some computers used RAM in page mode, in which you can read two or more words from sequential locations in rapid succession by only supplying the column address once, and ...
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34 votes
5 answers
17k views

Z80 x 6502 raw performance

A lot has been said on the internet about the 6502, at 1MHz, being roughly equivalent in performance to the Z80, at 4 MHz. It is said the Z80 has a typical 4 clock ticks per instruction, while the ...
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  • 1,507
8 votes
1 answer
702 views

Breakeven number of bytes for programmable DMA

Contemporary with the old 8-bit chips, existed powerful but unsung programmable DMA controllers like the Zilog 8410 and the Intel 8257, that could copy data from one memory location to another, much ...
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4 votes
1 answer
398 views

CPU speedup breaking sound compatibility

In the old days, it sometimes happened that a computer with a compatible but faster CPU, had problems running old games. For example, Sopwith was written for an 8088 PC; it was amusingly challenging ...
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5 votes
1 answer
1k views

How much faster is the Z80H?

The Z80A, rated for a maximum clock speed of 4 MHz, was a very widely used CPU in the 8-bit era. The Z80H, introduced in 1986, was rated for a maximum clock speed of 8 MHz. This would at first glance ...
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9 votes
3 answers
1k views

When did CPUs start using page mode DRAM?

According to https://en.wikipedia.org/wiki/Dynamic_random-access_memory#Page_mode_DRAM Page mode DRAM is a minor modification to the first-generation DRAM IC interface which improved the ...
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5 votes
7 answers
1k views

Benchmark between Home computers? What can be a valid parameter for that?

I'm writing my thesis about the home computer market between 1977 and 1984 (focusing on Commodore Inc.so PET, VIC-20 and 64 and competitors). I'm trying to plot a curve describing the technological ...
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25 votes
4 answers
5k views

Z8410 DMA chip as GPU?

There are basically two ways to design a 2D graphics system: Provide lots of hardware support in the form of tiles, hardware scrolling and sprites, to put together each frame on the fly from a small ...
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14 votes
7 answers
3k views

Z80 and video chip contending for random access

Back in the 8-bit days, I used 6502 computers, where the story about memory access was easy to understand. RAM chips of the late seventies and early eighties could do 2 MHz (or a bit more e.g. 2.6 in ...
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18 votes
4 answers
5k views

How fast is memcpy on the Z80?

I gather the fastest way to implement memcpy (copy a certain number of bytes from one place in memory to another) on the Z80 is to use an instruction called LDIR. But how fast is the result, when ...
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8 votes
3 answers
3k views

Floating point performance of classic minicomputers

Are there any numbers available for the floating point performance of classic minicomputers of the seventies and eighties? For example, the VAX 11/780 for integer calculations was generally rated in ...
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18 votes
5 answers
3k views

80s DRAM chips: one per bit of data bus width?

As I understand it, in the eighties the typical way of handling memory was one RAM chip per bit of data bus width. Suppose you were building a 16-bit machine and you wanted to give it 32K of RAM, you ...
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15 votes
3 answers
2k views

Speed of early ROM versus RAM chips

In the late seventies, up through around 1981, the maximum access speed of off-the-shelf RAM chips was around 2.6 MHz. Did the same speed limit apply to ROM chips of the same era? If not, what would ...
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  • 48.8k
3 votes
3 answers
1k views

How to compute performance of a CPU in FLOPS?

For a computer that took a variable number of clock cycles to execute floating point instructions, what would be the formula to estimate its performance in FLOPS assuming that it can execute either A ...
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11 votes
2 answers
2k views

When specifying Intel 80x86 instruction execution time, what is included in the cycle count?

I'm looking at this summary of the Intel x86 integer instruction set (though the same data seems to have been published in a number of places), which gives instruction timings on a per-instruction-...
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  • 4,956
21 votes
2 answers
3k views

68000 and memory access speed

On the one hand, I get the impression that memory chips around 1980 could be accessed no faster than 2 MHz. On the other hand, the 68000, introduced in 1979, had a typical clock speed of 8 MHz. How ...
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12 votes
6 answers
2k views

Memory-limited workloads

I'm trying to figure out whether computing workloads, particularly those related to science and engineering, have historically been limited by memory or CPU. (By the former, I mean not memory access ...
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13 votes
1 answer
2k views

Historical cost of computing (when was $1/FLOPS crossed?)

The relevant Wikipedia page has a large gap between 1961 and 1984, not allowing to estimate, even approximately, in what year the symbolic threshold of $1/FLOPS (or, as the wiki table puts it, $1bn/...
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