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| Unix for 8-bit Apple |
Posted by: Dog Cow on 2009-06-23 14:16:34
What do you go by on there, since I haven't seen Dog Cow as a name on any messages.
Dean I don't post. I just read the news on my site. See this topic: viewtopic.php?f=6&t=9839
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Posted by: magnusfalkirk on 2009-06-24 15:55:58
I don't post. I just read the news on my site. See this topic: viewtopic.php?f=6&t=9839 Yeah I saw that thread. It looked like a simple way to check up on CSA2 and some of the other groups I read if Google Groups goes down, which it has done from time to time. I've also looked over your site in general and like the looks of it. When will you be posting the Apple II stuff on there that you have?
Dean
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Posted by: Dog Cow on 2009-06-25 11:29:35
When will you be posting the Apple II stuff on there that you have? Hopefully in July or August. I need to update the Vault page, though. I've done more work since May.
It looked like a simple way to check up on CSA2 and some of the other groups I read if Google Groups goes down, Yeah, and the nice thing is that I get my news from a Dutch news server which doesn't censor the email addresses and all the other annoying things that Google does. xx(
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Posted by: Dog Cow on 2009-07-13 10:20:25
I read quite a few Usenet posts last evening on this subject, most from the late 80's. It looks like co-operative multitasking is going to be the way to go, unless one can get a card to generate interrupts every once and awhile. A program known as Daemon uses the Apple Mouse II card as its source of interrupts. Interestingly, the IIgs can be programmed, in software, to generate interrupts at varying intervals. Clearly, the superior system!
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Posted by: Dog Cow on 2009-07-26 18:34:38
OK, maybe I'm just talking to myself by now, but I found this site in Linux Journal magazine: http://www.freertos.org/
There's no port for the 6502/Apple yet, but I'm going to take a look at it and see what I can do.
FreeRTOS.org is a scaleable real time kernel designed specifically for small embedded systems. |
Posted by: Bunsen on 2009-07-26 18:52:29
Might want to investigate Minix. It's designed for teaching OS design, so even if a porting effort failed, it would be an educational fail 🙂 . It is to some extent unix-like.
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Posted by: porter on 2009-07-26 19:38:35
Might want to investigate Minix. It's designed for teaching OS design, so even if a porting effort failed, it would be an educational fail 🙂 . It is to some extent unix-like. I think you might be underestimating the requirements for a UNIX like OS. An 8Mhz 68000 struggles, so how a 6502 is supposed to cope I'm not sure.
What you have to do is stretch the definition of UNIX as much as your brain will allow in order to call the small bit of code you shoe horn into the box as something vaguely reminiscent of an idea they once had back at Bell that may have been somehow related to an operating system. If it doesn't have fork() then it ain't UNIX.
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Posted by: ChristTrekker on 2009-07-27 07:22:14
I think you might be underestimating the requirements for a UNIX like OS. An 8Mhz 68000 struggles, so how a 6502 is supposed to cope I'm not sure. Is it more limited than a PDP-7? I've no idea what kind of comparison that would be...
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Posted by: porter on 2009-07-27 09:22:16
Comparing a PDP-7 to a 6502 is not a bad comparison, especially when the UNIX group were using it, it was already considered obsolete. 🙂
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Posted by: Dog Cow on 2009-08-14 13:54:07
Just as update: this discussion is being continued on csa2p. There have been 9 replies since yesterday.
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Posted by: ChristTrekker on 2009-08-14 14:31:15
csa2p Took me a bit to figure out what that meant. 🙂
Sounds to me like targetting the IIgs, because it has the most resources, including a built-in source of interrupts, would make sense.
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Posted by: Dog Cow on 2009-08-17 10:52:46
Ah, but that would be the easy route, plus there's already GNO/ME.
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Posted by: ChristTrekker on 2009-08-17 13:01:15
Ah, but that would be the easy route, plus there's already GNO/ME. Bah, that's like MachTen or Mac06 on the Mac. Doesn't count! 😀
Targetting the GS first would be helpful as a springboard, learning some techniques for crunching down to low specs. Sure the architecture is quite a bit different, but some of the principles should be the same.
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Posted by: Osgeld on 2009-08-17 13:25:39
isnt the GS 16 bit?
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Posted by: Dog Cow on 2009-08-17 13:38:39
yeah, but you can also write 8-bit code because the 65c816 also knows about the 65c02.
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Posted by: ChristTrekker on 2009-08-17 14:22:26
isnt the GS 16 bit? The WDC 65816 (also: 65C816), a 16-bit microprocessor CPU developed by the Western Design Center (WDC), is an expanded and compatible successor to the venerable MOS Technology 6502. The number 65 in the 65816's name comes from the 6502 compatibility, and 816 signifies that it can work in both 8 and 16 bit modes.
If you're like me and don't really have a clue about interrupts, Interrupts in 65xx processors is a starting point.
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Posted by: ChristTrekker on 2009-08-20 12:32:45
The PDP-7 was an 18-bit machine. Has a "real Unix" ever been developed for any 8- or 16-bit machine? Doesn't seem a big stretch to run in 16 bits.
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Posted by: porter on 2009-08-20 15:35:31
The PDP-7 was an 18-bit machine. Has a "real Unix" ever been developed for any 8- or 16-bit machine? Doesn't seem a big stretch to run in 16 bits. The original QNX ran on 8088. It used the 8086 segmented model so a single process could use a maximum of 64k code+data+stack combined. And fork() really worked because it simply copied the whole proces image and used different segment register values. All pointers were, and had to be 16 bit ( AKA small model ). Processes could also be moved in memory. There was no memory protection at all and if you used assembler you could easily trash the system.
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Posted by: porter on 2009-08-20 16:57:31
The PDP-7 was an 18-bit machine. No, it was 16bit but could address 256Mb of memory with 18 address lines. A 6502 has 16 address lines but that doesn't make it a 16bit computer. If you went by that argument an 8086 was a 19bit computer and an 8088 was a 20bit computer.
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Posted by: ChristTrekker on 2009-08-21 10:04:24
No, it was 16bit but could address 256Mb of memory with 18 address lines. A 6502 has 16 address lines but that doesn't make it a 16bit computer. If you went by that argument an 8086 was a 19bit computer and an 8088 was a 20bit computer. My comment was based on what I read about it on Wikipedia, etc. I've never even seen a PDP-7. 🙂
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