Questions tagged [performance]

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25
votes
4answers
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 ...
14
votes
7answers
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 ...
14
votes
4answers
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 ...
6
votes
3answers
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 ...
8
votes
1answer
662 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 ...
26
votes
5answers
14k views

Z80 x 6502 raw performance

A lot have been said in the internet about the 6502 at 1MHz being roughly equivalent in performance to the Z80 at 4 MHz. Is said that the Z80 have a typical 4 clock ticks per instruction while the ...
17
votes
4answers
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 ...
12
votes
6answers
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 ...
6
votes
2answers
248 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 ...
4
votes
2answers
604 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 ...
5
votes
7answers
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 ...
3
votes
1answer
186 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 ...
3
votes
3answers
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 ...