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I wish Intel had just added some address lines and increased the price by $10 or whatever. I remember writing 68k assembly code and it was very pleasant to wor
by chihuahua 6y ago
I wish Intel had just added some address lines and increased the price by $10 or whatever.
I remember writing 68k assembly code and it was very pleasant to work with. 8 address registers, 8 data registers, if you want to access memory, you just put a 32-bit address into an address register.
Then I read a book about 80286 assembly and though "ugh this is horrible" and never wrote a single line of x86 assembly code. Worrying about segments and memory models (tiny, small, medium, compact, large, huge) seemed like such a drag on programmer productivity.
- microcolonel 6y ago> I wish Intel had just added some address lines and increased the price by $10 or whatever. It was at a magic price point though, ten dollars literally could have broken the whole product.
- kabdib 6y agoIt probably would have tipped IBM over to using the 68K. IIRC it was a near thing anyway.
- AnimalMuppet 6y agoI have heard that IBM chose the 8088 because Intel sowed some FUD about Motorola's ability to supply the 68000 in sufficient quantity for IBM. The decades of insanity we could have saved if IBM had chosen differently...
- pwg 6y agoThe Wikipedia page on AMD has a slightly different take (https://en.wikipedia.org/wiki/Amd#Technology_exchange_agreement_with_Intel https://en.wikipedia.org/wiki/Amd#Technology_exchange_agreem...): -quote- Technology exchange agreement with Intel Intel had introduced the first x86 microprocessors in 1978. In 1981, IBM created its PC, and wanted Intel's x86 processors, but only under the condition that Intel also provide a second-source manufacturer for its patented x86 microprocessors. Intel and AMD entered into a 10-year technology exchange agreement, first signed in October 1981 and formally executed in February 1982. The terms of the agreement were that each company could acquire the right to become a second-source manufacturer of semiconductor products developed by the other; that is, each party could "earn" the right to manufacture and sell a product developed by the other, if agreed to, by exchanging the manufacturing rights to a product of equivalent technical complexity. The technical information and licenses needed to make and sell a part would be exchanged for a royalty to the developing company. The 1982 agreement also extended the 1976 AMD–Intel cross-licensing agreement through 1995. The agreement included the right to invoke arbitration of disagreements, and after five years the right of either party to end the agreement with one year's notice. The main result of the 1982 agreement was that AMD became a second-source manufacturer of Intel's x86 microprocessors and related chips, and Intel provided AMD with database tapes for its 8086, 80186, and 80286 chips. -end quote- How much really was Intel sowing FUD vs. IBM demanding a second source be available is probably lost to time.
- bbojan 6y agoI've heard a story that due to the hardware divide instruction in 68000, IBM engineers were concerned about interrupt latency (the instruction took many cycles to execute and couldn't be pre-empted by in interrupt).
- SomeoneFromCA 6y ago8086 also had hardware div.
- Gibbon1 6y agoThe explanation I read back in the early 80's was Intel had the 8088 which required 8 DRAM chips. And the 68000 required 16 DRAM chips. For early microcomputers the cost of DRAM was the dominant cost.
- csharptwdec19 6y agoInteresting point. I know that with the Nintendo 64, the use of RDRAM was similar (lower overall chip count, which also helped with board cost in that case)
- Gibbon1 6y agoI think also a narrower data bus which might allow a smaller PCB with fewer layers. Used to be higher layer count PCB's $$$$. Friend worked on a layout where they did the board design first and then designed the processor pinout to match. So they could get away with a small two layer board. Ground on the bottom layer and all the signals on the top layer.
- fortran77 6y agoDecades of insanity? We've had decades of high-performance, low cost computing with three major OS choices (OSX, Windows, Linux) on the x86 platform.
- AnimalMuppet 6y agoAnd before that, we had decades of insanity. Segmentation. Six different memory models. Extended memory managers. Extended vs. expanded memory. Those needless complications burned tons of person-years of developer time that could have been spent on useful things.
- fortran77 6y agoHa! I almost forgot about having to choose a memory model when writing a program.
- a1369209993 6y agoIt's not a matter of address lines; registers are 16-bit (can addresss only 64 kilobytes), so you need segmentation regardless of whether your segements are mapped into 1MB, 16MB, or 4GB. (For Abus = Areg + Sreg << 4, 8, or 16 respectively.)
- ibiza 6y agoMotorola jumped from their 8-bit 6809 to a full 32-bit (internal) processor in 1979. Intel delivered a 32-bit processor 6 years later in 1985. Intel Motorola 1974 8080 8-bit 1974 6800 8-bit 1976 8085 8-bit 1978 6809 8-bit 1978 8086 16-bit 1979 68000 32-bit 1982 80286 16-bit 1985 80386 32-bit
- a1369209993 6y agoYes, but that's not a matter of "just add[ing] some address lines"; it's a matter of adding additional bits to the registers (and probably the ALU and internal data buses, but the registers are the limiting factor: if you don't have 32-bit registers you can't have (32-bit) flat address space). Even if it were "just", it would be "just add some register bits".