On Sat, 30 Aug 2025 03:06:11 -0400, c186282 wrote:
Tbe original 8088 had all the needed registers.
Could minimum deliver at LEAST an easy 64k code space and at LEAST
another 64k data area. A few tricks and .......
They mostly followed the bank switching the Z80s were doing but
incorporated the memory management into the processor. After all, the i432 was the REAL answer so why get fancy with the Band-Aid.
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT):
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
But there definitely was a period before that where the button vanished
(although there would have been motherboard pins if you wanted to dig
into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >> installed, pressing one side triggered NMI (used for invoking the resident >> debugger), while the other side triggered the RESET line (hard reboot).
I still have the muscle memory: seated in front of the machine, reach
around with right hand, far side was NMI, near side was RESET.
That's pretty cool, I always wished there was a physical switch to
trigger a debugger since the system might be frozen...
On 8/30/25 08:54, Scott Lurndal wrote:
Lawrence =?iso-8859-13?q?D=FFOliveiro?= <ldo@nz.invalid> writes:
On 29 Aug 2025 20:52:10 GMT, Ted Nolan <tednolan> wrote:
Using overlays was never straightforward, on any OS.
Typical troll comment.
There are existance proofs counter to your
unsupported blanket statement.
Burroughs medium systems for example, where using overlays was built
into the compilation tools (including the COBOL compiler) and the
operating system. Even the operating system used overlays for
rarely used functionality.
OS/360 and applications made extensive use of overlays.
I remember a (PC)-Dos application called "Enable" that overlayed like crazy.
It was typical to low-ball memory requirements to get a sale, then
sell the customer more memory afterwards when the system turned out
to be painfully slow and it was too late to back out.
On 2025-08-30, candycanearter07 ><candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
But there definitely was a period before that where the button vanished >>>> (although there would have been motherboard pins if you wanted to dig
into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >>> installed, pressing one side triggered NMI (used for invoking the resident >>> debugger), while the other side triggered the RESET line (hard reboot).
I still have the muscle memory: seated in front of the machine, reach
around with right hand, far side was NMI, near side was RESET.
That's pretty cool, I always wished there was a physical switch to
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
On 2025-08-30, Peter Flass <Peter@Iron-Spring.com> wrote:
On 8/30/25 08:54, Scott Lurndal wrote:
Lawrence =?iso-8859-13?q?D=FFOliveiro?= <ldo@nz.invalid> writes:
On 29 Aug 2025 20:52:10 GMT, Ted Nolan <tednolan> wrote:
Using overlays was never straightforward, on any OS.
Typical troll comment.
There are existance proofs counter to your
unsupported blanket statement.
Burroughs medium systems for example, where using overlays was built
into the compilation tools (including the COBOL compiler) and the
operating system. Even the operating system used overlays for
rarely used functionality.
OS/360 and applications made extensive use of overlays.
I remember a (PC)-Dos application called "Enable" that overlayed like crazy.
Univac's OS/3 (sort of a 360/370 workalike) had several utilities
that had as many as 45 overlays. This, combined with other
memory-squeezing tricks like "transients" (routines that rolled
in and out of special areas in memory) meant that the system drive
was typically thrashing furiously.
On 2025-08-30, candycanearter07 <candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
But there definitely was a period before that where the button vanished >>>> (although there would have been motherboard pins if you wanted to dig
into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >>> installed, pressing one side triggered NMI (used for invoking the resident >>> debugger), while the other side triggered the RESET line (hard reboot).
That's pretty cool, I always wished there was a physical switch to
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
On 2025-08-30, candycanearter07 <candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
But there definitely was a period before that where the button vanished >>>> (although there would have been motherboard pins if you wanted to dig
into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >>> installed, pressing one side triggered NMI (used for invoking the resident >>> debugger), while the other side triggered the RESET line (hard reboot).
I still have the muscle memory: seated in front of the machine, reach
around with right hand, far side was NMI, near side was RESET.
That's pretty cool, I always wished there was a physical switch to
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
On Tue, 02 Sep 2025 21:22:36 GMT, Charlie Gibbs wrote:
On 2025-08-30, candycanearter07
<candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:That's pretty cool, I always wished there was a physical switch to
But there definitely was a period before that where the button vanished >>>>> (although there would have been motherboard pins if you wanted to dig >>>>> into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >>>> installed, pressing one side triggered NMI (used for invoking the resident
debugger), while the other side triggered the RESET line (hard reboot). >>>
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
Interrupt button, surely.
On 2025-09-02 23:22, Charlie Gibbs wrote:
On 2025-08-30, candycanearter07
<candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
But there definitely was a period before that where the button vanished >>>>> (although there would have been motherboard pins if you wanted to dig >>>>> into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When >>>> installed, pressing one side triggered NMI (used for invoking the resident >>>> debugger), while the other side triggered the RESET line (hard reboot). >>>>
I still have the muscle memory: seated in front of the machine, reach
around with right hand, far side was NMI, near side was RESET.
That's pretty cool, I always wished there was a physical switch to
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
Nah. That's the reason you want a front panel so you can halt the
processor and change the PC to the debugger or crash dump function.
Because interrupt vectors, including NMI, would normally be in RAM, and could be changed to something else than your debugger or whatever.
(We are in a.f.c after all.)
On 2025-08-30, rbowman <bowman@montana.com> wrote:
On Sat, 30 Aug 2025 03:06:11 -0400, c186282 wrote:
Tbe original 8088 had all the needed registers.
Could minimum deliver at LEAST an easy 64k code space and at LEAST
another 64k data area. A few tricks and .......
They mostly followed the bank switching the Z80s were doing but
incorporated the memory management into the processor. After all, the
i432 was the REAL answer so why get fancy with the Band-Aid.
"It's a good thing the iAPX432 never took off. Otherwise a totally
horrid Intel architecture might have taken over the world."
On 28/08/2025 12:02, Carlos E.R. wrote:
Could MS-DOS (or CP/M) really make use of DMA?? Particularly since it
couldn’t even do multitasking or interrupt-driven I/O, so the OS driver >> would just sit there spinning its wheels until the I/O completed anyway.
Yes, MsDOS could.
I know for certain because I used (in the 90's) an analog data
acquisition card which came with routines for direct poll, interrupt driven, or dma driven. I still have the documentation.
However, it worked, IIRC, at the same frequency than the original IBM
PC. I have forgotten the exact explanation, but perhaps I have it
written somewhere. Probably related to the clock frequency of the bus on the ISA cards.
Floppy disk drive used DMA
On Tue, 02 Sep 2025 21:22:39 GMT
Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:
It was typical to low-ball memory requirements to get a sale, then
sell the customer more memory afterwards when the system turned out
to be painfully slow and it was too late to back out.
...whereas nowadays, we have to recommend our customers spec out twice
the memory they'd actually need as between Win10/11, the nine million
browser tabs everyone keeps open at all times, vendor bloatware, and
special gold-medal memory hogs like QuickBooks, an entry-level system
is full to bursting and swapping madly before they even load *our* >application...
...and half the damn time they buy the entry-level system anyway, and
then complain about *our* software being slow :/
In alt.folklore.computers The Natural Philosopher <tnp@invalid.invalid> wrote:
On 28/08/2025 12:02, Carlos E.R. wrote:
Yes, MsDOS could.
Could MS-DOS (or CP/M) really make use of DMA?? Particularly since it
couldn’t even do multitasking or interrupt-driven I/O, so the OS driver >>>> would just sit there spinning its wheels until the I/O completed anyway. >>>
I know for certain because I used (in the 90's) an analog data
acquisition card which came with routines for direct poll, interrupt
driven, or dma driven. I still have the documentation.
However, it worked, IIRC, at the same frequency than the original IBM
PC. I have forgotten the exact explanation, but perhaps I have it
written somewhere. Probably related to the clock frequency of the bus on >>> the ISA cards.
Floppy disk drive used DMA
That was more for latency purposes. The floppy controller had a very small FIFO, so when data arrived from the disc you had to do *something* with it
in short order otherwise the byte coming next would have to be dropped.
DMA was the solution - you didn't need the CPU to do anything, you could
just stash it in RAM via DMA.
That was important when you had a ~500Kbps data stream from the FDC and only a 4.77MHz CPU. But there was only so much memory bandwidth to go around and at that point the floppy was taking a big chunk, so not a lot of progress would be made on the CPU while DMA was busy hammering the memory.--
Since the IBM PC had a DMA controller on the motherboard for that reason
(and also DRAM refresh), it was then reasonably easy to make ISA cards that streamed data via DMA - you could just put your data on the data bus and generate basic DMARQ / DMACK cycles to store it to RAM, without having to worry about generating addresses since the 8237 did that for you.
Theo
On 2025-09-02, Lawrence D’Oliveiro <ldo@nz.invalid> wrote:
On Tue, 02 Sep 2025 21:22:36 GMT, Charlie Gibbs wrote:
On 2025-08-30, candycanearter07
<candycanearter07@candycanearter07.nomail.afraid> wrote:
Lawrence D’Oliveiro <ldo@nz.invalid> wrote at 03:27 this Saturday (GMT): >>>>
On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:That's pretty cool, I always wished there was a physical switch to
But there definitely was a period before that where the button vanished >>>>>> (although there would have been motherboard pins if you wanted to dig >>>>>> into it).
Apple included a little springy clip thing (the “Programmers’s Switch”) in
the box with each of those original classic-form-factor Macintoshes. When
installed, pressing one side triggered NMI (used for invoking the resident
debugger), while the other side triggered the RESET line (hard reboot). >>>>
trigger a debugger since the system might be frozen...
And that, ladies and gentlemen, is why you want a reset button
rather than having to resort to the power switch.
Interrupt button, surely.
Maybe we need a series of buttons in a row, e.g. NMI, reset, power...
And don't call me Shirley.
On Wed, 27 Aug 2025 16:40:27 +0200
Alexander Schreiber <als@usenet.thangorodrim.de> wrote:
[]
I haven't tried Unix on 8086, but DOS on x86 essentially relied on applications
being reasonably correct and not too buggy. Having the reset button conveniently
accessible was effectively a requirement for any DOS PC ;-)
Unix on an early IBM PC (8086, 10M hard drive) would have been quite a shoehorning job. 'Slow' would probably be a generous word to use.
In alt.folklore.computers The Natural Philosopher <tnp@invalid.invalid> wrote:
On 28/08/2025 12:02, Carlos E.R. wrote:
Yes, MsDOS could.
Could MS-DOS (or CP/M) really make use of DMA?? Particularly since it
couldn’t even do multitasking or interrupt-driven I/O, so the OS driver >> >> would just sit there spinning its wheels until the I/O completed anyway. >> >
I know for certain because I used (in the 90's) an analog data
acquisition card which came with routines for direct poll, interrupt
driven, or dma driven. I still have the documentation.
However, it worked, IIRC, at the same frequency than the original IBM
PC. I have forgotten the exact explanation, but perhaps I have it
written somewhere. Probably related to the clock frequency of the bus on >> > the ISA cards.
Floppy disk drive used DMA
That was more for latency purposes. The floppy controller had a very small FIFO, so when data arrived from the disc you had to do *something* with it
in short order otherwise the byte coming next would have to be dropped.
DMA was the solution - you didn't need the CPU to do anything, you could
just stash it in RAM via DMA.
That was important when you had a ~500Kbps data stream from the FDC and only a 4.77MHz CPU. But there was only so much memory bandwidth to go around and at that point the floppy was taking a big chunk, so not a lot of progress would be made on the CPU while DMA was busy hammering the memory.
"What would YOU do with 128 GiB of RAM, Dan?"
"Run two electron apps at the same time...."
On Wed, 3 Sep 2025 10:40:39 -0000 (UTC) cross@spitfire.i.gajendra.net
(Dan Cross) wrote:
"What would YOU do with 128 GiB of RAM, Dan?"
"Run two electron apps at the same time...."
*Painfully* accurate :/
On Wed, 3 Sep 2025 07:59:08 -0700, John Ames wrote:
On Wed, 3 Sep 2025 10:40:39 -0000 (UTC) cross@spitfire.i.gajendra.net
(Dan Cross) wrote:
"What would YOU do with 128 GiB of RAM, Dan?"
"Run two electron apps at the same time...."
*Painfully* accurate :/
VS Code is an electron app and is not using excessive memory. Who is the >prime offender? Pan at 11.4%.
In alt.folklore.computers Kerr-Mudd, John <admin@127.0.0.1> wrote:
On Wed, 27 Aug 2025 16:40:27 +0200
Alexander Schreiber <als@usenet.thangorodrim.de> wrote:
[]
I haven't tried Unix on 8086, but DOS on x86 essentially relied on applications
being reasonably correct and not too buggy. Having the reset button conveniently
accessible was effectively a requirement for any DOS PC ;-)
Unix on an early IBM PC (8086, 10M hard drive) would have been quite a shoehorning job. 'Slow' would probably be a generous word to use.
That reminds me to check on how:
https://github.com/ghaerr/elks
is doing. Still seems to be alive and kicking, most recent release in October.
Fits in 512KB of RAM on an 8086 and uses a single floppy.
Of course it's Linux(ish) and not Unix.
In alt.folklore.computers The Natural Philosopher <tnp@invalid.invalid> wrote:
Floppy disk drive used DMA
That was more for latency purposes. The floppy controller had a very
small FIFO, so when data arrived from the disc you had to do *something*
with it in short order otherwise the byte coming next would have to be dropped.
DMA was the solution - you didn't need the CPU to do anything, you could
just stash it in RAM via DMA.
PC was no more constained than 360/30, where simultaneous I/O and
computation was common.
In alt.folklore.computers Theo <theom+news@chiark.greenend.org.uk> wrote:
In alt.folklore.computers The Natural Philosopher <tnp@invalid.invalid> wrote:
On 28/08/2025 12:02, Carlos E.R. wrote:
Yes, MsDOS could.
Could MS-DOS (or CP/M) really make use of DMA?? Particularly since it >>> >> couldn’t even do multitasking or interrupt-driven I/O, so the OS driver
would just sit there spinning its wheels until the I/O completed anyway. >>> >
I know for certain because I used (in the 90's) an analog data
acquisition card which came with routines for direct poll, interrupt
driven, or dma driven. I still have the documentation.
However, it worked, IIRC, at the same frequency than the original IBM >>> > PC. I have forgotten the exact explanation, but perhaps I have it
written somewhere. Probably related to the clock frequency of the bus on >>> > the ISA cards.
Floppy disk drive used DMA
That was more for latency purposes. The floppy controller had a very small >> FIFO, so when data arrived from the disc you had to do *something* with it >> in short order otherwise the byte coming next would have to be dropped.
DMA was the solution - you didn't need the CPU to do anything, you could
just stash it in RAM via DMA.
That was important when you had a ~500Kbps data stream from the FDC and only >> a 4.77MHz CPU. But there was only so much memory bandwidth to go around and >> at that point the floppy was taking a big chunk, so not a lot of progress
would be made on the CPU while DMA was busy hammering the memory.
Floppy was taking about 5% of memory bandwidth, plenty of cycles
remaing to do CPU work. Even hard disc left enough cycles to do
some useful CPU work. Not doing computation during floppy DMA
transfer was just unwilingness to do more complex implementation.
PC was no more constained than 360/30, where simultaneous I/O
and computation was common.
In alt.folklore.computers Rich <rich@example.invalid> wrote:
In comp.os.linux.misc c186282 <c186282@nnada.net> wrote:
... REAL power switch, like a 3-sec
delay before anything happens.
Only for ATX PSU based machines. The old AT PSU spec had the power
switch as an actual switch that interrupted mains power.
Granted, few remember AT PSU based systems anymore, and even fewer of
them are still in service.
Many PC have real power switch. There is software controlled one at
the front and real one built into the power supply.
Apple managed it without DMA. And remember their floppies had higher capacity than IBM’s.True, but it's much harder to do precise timing on an 8088 than a 6502;
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of
the case that user's used to turn on/off the machine.
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of
the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply at
the back of the machine, but it was activated via a long rod that ended
in a button on the front panel.
On Wed, 3 Sep 2025 23:09:49 -0000 (UTC)
Lawrence D’Oliveiro <ldo@nz.invalid> wrote:
Apple managed it without DMA. And remember their floppies had higher
capacity than IBM’s.
True, but it's much harder to do precise timing on an 8088 than a 6502;
the combination of prefetch queue obscurity (which *is* calculable, in a sufficiently tight loop) and DRAM refresh (which isn't) yields a lot of uncertainty wrt. real-world execution times.
On Thu, 04 Sep 2025 18:38:23 GMT, Charlie Gibbs wrote:
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of
the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply at
the back of the machine, but it was activated via a long rod that ended
in a button on the front panel.
All I know is at some point the power button on front of the box would
turn the machine on. Pushing it again was a mild suggestion that the
machine shut down if it felt like it. The cord was usually easier to find >when groping around than the toggle on the PS.
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that interrupted mains power was the switch that was mounted in the front of the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply
at the back of the machine, but it was activated via a long rod that
ended in a button on the front panel.
On Thu, 04 Sep 2025 18:38:23 GMT
Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of >>> the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply
at the back of the machine, but it was activated via a long rod that
ended in a button on the front panel.
PS2 ?
https://en.wikipedia.org/wiki/IBM_PS/2_Model_30#/media/File:IBM_PS-2_Model_30_286_open_top.jpg
On Thu, 04 Sep 2025 18:38:23 GMT
Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of
the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply
at the back of the machine, but it was activated via a long rod that
ended in a button on the front panel.
PS2 ?
https://en.wikipedia.org/wiki/IBM_PS/2_Model_30#/media/File:IBM_PS-2_Model_30_286_open_top.jpg
rbowman <bowman@montana.com> writes:
On Thu, 04 Sep 2025 18:38:23 GMT, Charlie Gibbs wrote:
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of >>>> the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply at
the back of the machine, but it was activated via a long rod that ended
in a button on the front panel.
All I know is at some point the power button on front of the box would
turn the machine on. Pushing it again was a mild suggestion that the
machine shut down if it felt like it. The cord was usually easier to find
when groping around than the toggle on the PS.
The firmware has managed the power switch for the last couple of
decades. The OS can arrange with the SMM firmware (through ACPI) to
manage the power button to ensure that on-disk state remains
consistent by shutting down the applications and operating systems
cleanly.
Works pretty well with Linux. Some windows applications have not,
in the past, played well with soft power switches, and some
BIOS implementations have been sub-par, to put it kindly.
On 2025-09-04, Rich <rich@example.invalid> wrote:
For the pre ATX PSU's (AT PSU's), the physical power switch that
interrupted mains power was the switch that was mounted in the front of
the case that user's used to turn on/off the machine.
I saw some machines where the actual switch was in the power supply
at the back of the machine, but it was activated via a long rod that
ended in a button on the front panel.
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