#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market.
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There are also apps that do the same “upper 8 bits are for flags” thing. If you are in 32-bit mode (i.e. all 32 address lines are enabled) while such an app is running, the app will read/write the wrong memory locations, causing crashes or worse.
As I recall, apps were supposed to use the ROM memory manager rather than making up pointers themselves, and would therefore work in 32-bit mode, but some apps were naughty, presumably in order to run faster.
Only a few Mac models ever had this problem: the Mac II, IIx, IIcx, and SE/30.
Earlier/lower-end Macs had a 68000 or 68010 and therefore couldn't do 32-bit addressing at all. In later Macs, Apple fixed the ROM and 32-bit addressing was always enabled.
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#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market. I want everyone's input! Please boost!
These questions are specifically about all 32-bit comsumer machines: PCs, Macs, RISC machines, you name it. Mid 1980s to 2005-ish.
(I'm also concurrently running a poll for 8 and 16-bit home computers and another for minicomputers. I'll probably have to do another for UNIX Workstations and LISP machines!)
Hat tip to @Foritus!
My family's first computer had a 486. The badge on the case proudly announced that it was 32-bit.
It ran MS-DOS and Windows 3.1, both of which were generally regarded as 16-bit. At the time, I lamented that the 32-bit capabilities of its CPU were wasted on this software configuration.
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My family's first computer had a 486. The badge on the case proudly announced that it was 32-bit.
It ran MS-DOS and Windows 3.1, both of which were generally regarded as 16-bit. At the time, I lamented that the 32-bit capabilities of its CPU were wasted on this software configuration.
Little did I know that Windows 3.1 very definitely does use 32-bit addressing! Apps run in real mode and still use the 8086's weird segmented addressing, but the Windows kernel runs in 32-bit mode and maps memory in and out of that space, somewhat like swap on a modern operating system (except triggered by GlobalLock calls instead of page faults).
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#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market. I want everyone's input! Please boost!
These questions are specifically about all 32-bit comsumer machines: PCs, Macs, RISC machines, you name it. Mid 1980s to 2005-ish.
(I'm also concurrently running a poll for 8 and 16-bit home computers and another for minicomputers. I'll probably have to do another for UNIX Workstations and LISP machines!)
Hat tip to @Foritus!
@genehack raise your hand if you know it
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If MODE32 works on it, then the hardware is 32-bit, but the ROM code isn't.
The problem is that said ROM code uses the upper 8 bits of pointers to store flags instead of address bits, and disables the upper 8 address lines.
This makes sense on the original Mac, whose 68000 has only 24 address lines and *always* ignores the upper 8 bits. But a 68020 or newer has 32 address lines, so this ROM behavior wastes the CPU's potential.
MODE32 patches the ROM to fix this.
@argv_minus_one @flargh @fluidlogic @Foritus TIL that there’s a worse option than 8088-style “segmented” memory addressing
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#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market. I want everyone's input! Please boost!
These questions are specifically about all 32-bit comsumer machines: PCs, Macs, RISC machines, you name it. Mid 1980s to 2005-ish.
(I'm also concurrently running a poll for 8 and 16-bit home computers and another for minicomputers. I'll probably have to do another for UNIX Workstations and LISP machines!)
Hat tip to @Foritus!
@fluidlogic @Foritus when 64-bit computers were new (around 2005) I worked for a company that used QuickBooks, and got to talk Intuit tech support through how to install the QuickBooks server on a 64-bit Linux host
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@argv_minus_one @flargh @fluidlogic @Foritus TIL that there’s a worse option than 8088-style “segmented” memory addressing
Nah, at least 68000 pointers are flat and unambiguous. 8086 far pointers are just as long (32 bits) and can't even be compared for equality doing a bunch of math first. And 8086 near pointers can't be compared at all unless you know which segment they both point into.
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#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market. I want everyone's input! Please boost!
These questions are specifically about all 32-bit comsumer machines: PCs, Macs, RISC machines, you name it. Mid 1980s to 2005-ish.
(I'm also concurrently running a poll for 8 and 16-bit home computers and another for minicomputers. I'll probably have to do another for UNIX Workstations and LISP machines!)
Hat tip to @Foritus!
@Foritus @fluidlogic wait, when did 32bit machines' heyday end?
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Little did I know that Windows 3.1 very definitely does use 32-bit addressing! Apps run in real mode and still use the 8086's weird segmented addressing, but the Windows kernel runs in 32-bit mode and maps memory in and out of that space, somewhat like swap on a modern operating system (except triggered by GlobalLock calls instead of page faults).
@argv_minus_one @fluidlogic @Foritus Windows 3.1 is weirder than that – in Enhanced mode, it's really a hypervisor running at least one virtual machine (which is running Standard mode Windows 3.1), the other virtual machines are DOS boxes if you're running any.
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#retrocomputing folks: I'm trying to get a sense of the proportion of people here who are into retrocomputing today but didn't experience certain classes of machines when they first came on the market. I want everyone's input! Please boost!
These questions are specifically about all 32-bit comsumer machines: PCs, Macs, RISC machines, you name it. Mid 1980s to 2005-ish.
(I'm also concurrently running a poll for 8 and 16-bit home computers and another for minicomputers. I'll probably have to do another for UNIX Workstations and LISP machines!)
Hat tip to @Foritus!
@fluidlogic @Foritus What about 16- and 36-bit computers?
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