Printed Amstrad Addict magazine announced, check it out here!
Started by sigh, 13:21, 23 December 10
0 Members and 1 Guest are viewing this topic.
QuoteAlthough all registers are still just 8 bits wide, the 65CE02 provides some 16 bit instructions, mainly in Red-Modify-Write instructions: ASW $nnnn CB Arithmetic Shift Left Word DEW $nnnn C3 Decrement Word INW $nnnn E3 Increment Word (ERROR IN 64NET.OPC?) PHW #$nnnn F4 Push Word $nnnn FC ROW $nnnn EB Rotate Right Word Note that some of these instructions support the 16-bit rotate/shift instructions of the 65SC02 mentioned above.
Quote from: robcfg on 20:30, 31 December 10In the text file linked in the wikipedia article, I found this:There was also a 6502 16-bit upgraded version that was the 65816, which was used on the SNES.And of top of that, the R800 in the turboR ran at 7.16 mhz and it took 4 times less clock cycles to execute the instructions.
Quote from: MacDeath on 13:18, 27 December 10Were 8 bit "duocore" ever crafted ?
Quote from: fano on 10:24, 02 January 11For example the SNES cpu is named as a 16 bits CPU but its data bus width is 8bits so does SNES is a 8 or a 16 bits machine ?
Quote from: redbox on 12:35, 02 January 11 You are right, it is difficult. The SNES would definitely be classed as 16-bit though I always thought the PC Engine was 8-bit and the best one there is, but it appears that is debatable. The one that always made me smile was the Atari Jaguar because they said it was "64-bit" but really that was only the data bus size too if I remember correctly.
Quote from: Briggsy on 22:17, 30 April 11Yeah, there's a few new 8-bit designs using the Z80, some RAM and a more modern Atmel AVR for other logic. Or even just the AVR (as it is a full 8-bit RISC at 16MHz) http://www.bbc.co.uk/news/technology-13201254As for the bittiness of a CPU, I think these days you would look at the register size first, then the ALU width, and lastly the data bus width. You would also want to consider things more holistically in terms of the features, etc.68000 - 32-bit registers, 16-bit ALU, 16-bit data bus and 24-bit address bus (but address registers were 32-bit). It's always been referred to as a 16/32 bit processor. The Amiga/ST/Megadrive labelled themselves 16-bit, but that's also because of the support chips.68008 - 32-bit registers, 16-bit ALU, 8-bit data bus and 20-bit address bus (IIRC)Z80 - 8 bit registers with pairing capability and some 16-bit instructions, 8-bit ALU, 8-bit data bus, 16-bit address bus. The Z180/R800 showed that the instruction set and design could be extended to full 16-bit. The eZ80 extends it to 32-bit IIRC.6502 - 8-bit registers, 8-bit ALU, 8-bit data bus, 16-bit address bus. Again, extended later on.The downside of having an ALU width half the size of the registers was merely that instructions took longer to execute when operating on the full register width. Therefore it's just an implementation issue - saving transistors at the cost of instructions per clock.With that in mind, was the Z80 8-bit or 16-bit? Holistically you would say it's 8-bit - it's designed from an 8-bit heritage, the registers are all 8-bit accessible, the 16-bit instructions take a lot longer to execute, it only addresses 64KB, etc. But it's more 16-bit than the 6502!
Quote from: CP/M User on 23:34, 30 April 11 Interesting the 68008 is 8bit cause it's Bus will only allow it! Surely if it only has an 8bit data bus though has 32-bit registers, 16-bit ALU and 20-bit address bus, there must be some advantage in having those things?
Quote from: steve on 23:50, 30 April 11The advantage of the 8-bit bus is that a computer system is cheaper to manufacture than a 16-bit bus system, yet the 68008 can execute 68000 code only 30% slower then the 16-bit 68000, and therefore a reasonable compromise between speed and cost.
QuoteIf a version of the Z80 were made with a 16 or 32 bit data bus, it would execute code faster, but would still be an 8-bit processor.
Quote from: CP/M User on 11:30, 01 May 11Yeah there probably wasn't too many high end businessmen back then that wanted maximum performance and would have it at any cost!
Quote from: MacDeath on 12:50, 01 May 11Weren't some Z80 built to run at (impressive) 16mhz ?
Quote from: steve on 00:25, 02 May 11The Sinclair QL used a 68008, it was also manufactured as the ICL "one per desk" and sold to the corporate world, it was functionality that counted then, speed came later, in fact few people demanded more speed, what they had was fast enough, but they were persuaded that getting something faster would increase productivity, and they have been falling for the same lie ever since.
Quote from: MaV on 09:34, 02 May 11It's those effin businessmen in particular that don't need any kind of max performance. We've had the equivalent of Word, Excel and Powerpoint already back then, and they worked ok. Performance is needed for games, technical jobs or video and sound editing and the like.
QuoteEven non-technical people are starting to realize that 2GB, 4GB, or even 8GB of RAM doesn't make much of a difference for everyday tasks anymore. The only reason I can come up with to use 8GB would be virtual machines.
QuoteIt also makes no sense buying ever faster processors these day, when the main bottleneck of computers is the hard-drive.
Quote from: Gryzor on 07:47, 03 May 11Regarding performance, it depends. Try telling my entire marketing department, running Photoshop on each workstation, that they don't need more than 1GB
Page created in 0.125 seconds with 25 queries.