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Re: Terminology query - 'system process'?

by jnc＠mercury.lcs.mit.edu

> the first DEC machine with an IC processor was the -11/20, in 1970 Clem has reminded me that the first was the PDP-8/I-L (the second was a cost-reduced version of the -I), from. The later, and much more common, PDP-8/E-F-M, were contemporaneous with the -11/20. Oh well, only two years; doesn't really affect my main point. Just about 'blink and you'll miss them'! Noel

1 year, 8 months

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Re: Terminology query - 'system process'?

by jnc＠mercury.lcs.mit.edu

> From: Bakul Shah > Now I'd probably call them kernel threads as they don't have a separate > address space. Makes sense. One query about stacks, and blocking, there. Do kernel threads, in general, have per-thread stacks; so that they can block (and later resume exactly where they were when they blocked)? That was the thing that, I think, made kernel processes really attractive as a kernel structuring tool; you get code ike this (from V6): swap(rp->p_addr, a, rp->p_size, B_READ); mfree(swapmap, (rp->p_size+7)/8, rp->p_addr); The call to swap() blocks until the I/O operation is complete, whereupon that call returns, and away one goes. Very clean and simple code. Use of a kernel process probably makes the BSD pageout daemon code fairly straightforward, too (well, as straightforward as anything done by Berzerkly was :-). Interestingly, other early systems don't seem to have thought of this structuring technique. I assumed that Multics used a similar technique to write 'dirty' pages out, to maintain a free list. However, when I looked in the Multics Storage System Program Logic Manual: http://www.bitsavers.org/pdf/honeywell/large_systems/multics/AN61A_storageS… Multics just writes dirty pages as part of the page fault code: "This starting of writes is performed by the subroutine claim_mod_core in page_fault. This subroutine is invoked at the end of every page fault." (pg. 8-36, pg. 166 of the PDF.) (Which also increases the real-time delay to complete dealing with a page fault.) It makes sense to have a kernel process do this; having the page fault code do it just makes that code more complicated. (The code in V6 to swap processes in and out is beautifully simple.) But it's apparently only obvious in retrospect (like many brilliant ideas :-). Noel

1 year, 8 months

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Terminology query - 'system process'?

by jnc＠mercury.lcs.mit.edu

So Lars Brinkhoff and I were chatting about daemons: https://gunkies.org/wiki/Talk:Daemon and I pointed out that in addition to 'standard' daemons (e.g. the printer spooler daemon, email daemon, etc, etc) there are some other things that are daemon-like, but are fundamentally different in major ways (explained later below). I dubbed them 'system processes', but I'm wondering if ayone knows if there is a standard term for them? (Or, failing that, if they have a suggestion for a better name?) Early UNIX is one of the first systems to have one (process 0, the "scheduling (swapping) process"), but the CACM "The UNIX Time-Sharing System" paper: https://people.eecs.berkeley.edu/~brewer/cs262/unix.pdf doesn't even mention it, so no guidance there. Berkeley UNIX also has one, mentioned in "Design and Implementation of the Berkeley Virtual Memory Extensions to the UNIX Operating System": http://roguelife.org/~fujita/COOKIES/HISTORY/3BSD/design.pdf where it is called the "pageout daemon".("During system initialization, just before the init process is created, the bootstrapping code creates process 2 which is known as the pageout daemon. It is this process that .. writ[es] back modified pages. The process leaves its normal dormant state upon being waken up due to the memory free list size dropping below an upper threshold.") However, I think there are good reasons to dis-favour the term 'daemon' for them. For one thing, typical daemons look (to the kernel) just like 'normal' processes: their object code is kept in a file, and is loaded into the daemon's process when it starts, using the same mechanism that 'normal' processes use for loading their code; daemons are often started long after the kernel itself is started, and there is usually not a special mechanism in the kernel to start daemons (on early UNIXes, /etc/rc is run by the 'init' process, not the kernel); daemons interact with the kernel through system calls, just like 'ordinary' processes; the daemon's process runs in 'user' CPU mode (using the same standard memory mapping mechanisms, just like blah-blah). 'System processes' do none of these things: their object code is linked into the monolithic kernel, and is thus loaded by the bootstrap; the kernel contains special provision for starting the system process, which start as the kernel is starting; they don't do system calls, just call kernel routines directly; they run in kernel mode, using the same memory mapping as the kernel itself; etc, etc. Another important point is that system processes are highly intertwined with the operation of the kernel; without the system process(es) operating correctly, the operation of the system will quickly grind to a halt. The loss of ordinary' daemons is usually not fatal; if the email daemon dies, the system will keep running indefinitely. Not so, for the swapping process, or the pageout daemon Anyway, is there a standard term for these things? If not, a better name than 'system process'? Noel

1 year, 8 months

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ITS 138 listing from 1967

by Lars Brinkhoff

For the benefit of Old Farts around here, I'd like to share the good word that an ITS 138 listing from 1967 has been discovered. A group of volunteers is busy transcribing the photographed pages to text. Information and link to the data: https://gunkies.org/wiki/ITS_138 This version is basically what ITS first looked like when it went into operation at the MIT AI lab. It's deliciously arcane and primitive. Mass storage is on four DECtape drives, no disk here. Users stations consist of five teletypes and four GE Datanet 760 CRT consoles (46 colums, 26 lines). The number of system calls is a tiny subset of what would be available later. There are more listings from 1967-1969 for DDT, TECO, LISP, etc. Since they are fan-fold listings, scanning is a bit tricky, so a more labor- intensive photographing method is used.

1 year, 8 months

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Western Electric 321 Development System Schematics?

by segaloco

Hello everyone, I was wondering if anyone is aware of any surviving technical diagrams/schematics for the WECo 321EB or WECo 321DS WE32x00 development systems? Bitsavers has an AT&T Data Book from 1987 detailing pin maps, registers, etc. of 32xxx family ICs and then another earlier manual from 1985 that seems to be more focused on a technical overview of the CPU specifically. Both have photographs and surface level block diagrams, but nothing showing individual connections, which bus leads went where, etc. While the descriptions should be enough, diagrams are always helpful. In any case, I've recently ordered a 32100 CPU and 32101 MMU I saw sitting on eBay to see what I can do with some breadboarding and some DRAM/DMA controllers from other vendors, was thinking of referring to any available design schematics of the 321 development stuff for pointers on integrations. Either way, i'm glad the data books on the hardware have been preserved, that gives me a leg up. Thanks for any insights! - Matt G.

1 year, 8 months

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Famicom Disk System Software Disassembly (Doki Doki Panic)

by segaloco

Good day everyone, I thought I'd share a new project I've been working on since it is somewhat relevant to old and obscure computing stuff that hasn't gotten a lot of light shed on it. https://gitlab.com/segaloco/doki After the link is an in-progress disassembly of Yume Kojo: Doki Doki Panic for the Famicom Disk System, known better in the west as the engine basis for Super Mario Bros. 2 for the NES (the one with 4 playable characters, pick-and-throw radishes, etc.) What inspired me to start on this project is the Famicom Disk System is painfully under-documented, and what is out there is pretty patchy. Unlike with its parent console, no 1st party development documentation has been archived concerning the Disk System, so all that is known about its programming interfaces have been determined from disassemblies of boot ROMs and bits and pieces of titles over the years. The system is just that, a disk drive that connects to the Famicom via a special adapter that provides some RAM, additional sound functionality, and some handling for matters typically controlled by the cartridge (background scroll-plane mirroring and saving particularly.) The physical disk format is based on Mitsumi's QuickDisk format, albeit with the casing extended in one dimension as to provide physical security grooves that, if not present, will prevent the inserted disk from booting. The hardware includes a permanently-resident boot ROM which maps to 0xE000-0xFFFF (and therefore provides the 6502 vectors). This boot ROM in turn loads any files from the disk that match a specified pattern in the header to header-defined memory ranges and then acts on a secondary vector table at 0xDFFA (really 0xDFF6, the disk system allows three separate NMI vectors which are selected from by a device register.) The whole of the standard Famicom programming environment applies, although the Disk System adds an additional bank of device registers in a reserved memory area and exposes a number of "syscalls" (really just endpoints in the 0xE000-0xFFFF range, it's unknown at present to what degree these entries/addresses were documented to developers.) I had to solve a few interesting challenges in this process since this particular area gets so little attention. First, I put together a utility and supporting library to extrapolate info from the disk format. Luckily the header has been (mostly) documented, and I was able to document a few consistencies between disks to fill in a few of the parts that weren't as well documented. In any case, the results of that exercise are here: https://gitlab.com/segaloco/fdschunk. One of the more interesting matters is that the disk creation and write dates are stored not only in BCD, but the year is not always Gregorian. Rather, many titles reflect instead the Japanese period at the time the title was released. For instance, the Doki Doki Panic image I'm using as a reference is dated (YY/MM/DD) "61/11/26" which is preposterous, the Famicom was launched in 1983, but applying this knowledge of the Showa period, the date is really "86/11/26" which makes much more sense. This is one of those things I run into studying Japanese computing history time to time, I'm sure the same applies to earlier computing in other non-western countries. We're actually headed for a "2025-problem" with this time-keeping as that is when the Showa calendar rolls over. No ROMs have been recovered from disk writer kiosks employed by Nintendo in the 80s, so it is unknown what official hardware which applies these timestamps does when that counter rolls over. I've just made the assumption that it should roll back to 00, but there is no present way to prove this. The 6502 implementation in the Famicom (the Ricoh 2A03) omitted the 6502 BCD mode, so this was likely handled either in software or perhaps a microcontroller ROM down inside the disk drives themselves. I then had to solve the complementary problem, how do I put a disk image back together according to specs that aren't currently accessible. Well, to do that, I first chopped the headers off of every first-party Nintendo image I had in my archive and compared them in a table. I diverted them into two groups: pristine images that represent original pressings in a Nintendo facility and "dirty" images that represent a rewrite of a disk at one of the disk kiosks (mind you, Nintendo distributed games both ways, you could buy a packaged copy or you could bring a rewritable disk to a kiosk and "download" a new game.) My criterion for categorization was whether the disk create and modify times were equal or not. This allowed me to get a pretty good picture of what headers getting pumped out of the factory look like, and how they change when the disk is touched by a writer kiosk. I then took the former configuration and wrote a couple tools to consume a very spartan description of the variable pieces and produce the necessary images: https://gitlab.com/segaloco/misc/-/tree/master/fds. These tools, bintofdf and fdtc, apply a single file header to a disk file and create a "superblock" for a disk side respectively. I don't know what the formal terms are, they may be lost to time, but superblock hopefully gets the point across, albeit it's not an exact analog to UNIX filesystems. Frankly I can't find anything regarding what filesystem this might be based on, if at all, or if it is an entirely Nintendo-derived format. In any case, luckily the header describing a file is self-contained on that file, and then the superblock only needs to know how many files are present, so the two steps can be done independently. The result is a disk image, stamped with the current Showa BCD date, that is capable of booting on the system. The only thing I don't add that "pure" disks contain are CRCs of the files. On a physical disk, these header blocks also contain CRCs of the data they describe, these, by convention, are omitted from disk dumps. I'm actually not entirely sure why, but I imagine emulator writers just omit the CRC check as well, so it doesn't matter to folks just looking to play a game. Finally, there's the matter of disparate files which may or may not necessarily be sitting in memory at runtime. Luckily the linker script setup in cc65 (the compiler suite I'm using) is pretty robust, and just like my Dragon Quest disassembly (which is made up of swappable banks) I was able to use the linker system to produce all of the necessary files in isolation, rather than having to get creative with orgs and compilation order to clobber something together that worked. This allows the code to be broken down into its logical structure rather than just treating a whole disk side as if it was one big binary with .org commands all over the place. Anywho, I don't intend on a rolling update to this email or anything, but if this is something that piques anyone's interest and you'd like to know more, feel free to shoot me a direct reply. I'd be especially interested in any stories or info regarding Mitsumi QuickDisk, as one possibility is that Nintendo's format is derived from something of their own, with reserved/undefined fields redefined for Nintendo's purposes. That said, it's just a magnetic disk, I would be surprised if a single filesystem was enforced in all implementations. Thanks for following along! - Matt G. P.S. As always contributions to anything I'm working on are welcome and encouraged, so if you have any input and have a GitLab account, feel free to open an issue, fork and raise a PR, etc.

1 year, 10 months

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Happy birthday, VisiCalc!

by Dave Horsfall

Released on this day in 1979, it was the original "killer app" (how I loathe that term). -- Dave

1 year, 10 months

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Re: "Hot Spot" High Performing Centres in Computing

by jnc＠mercury.lcs.mit.edu

> From: Dan Cross > This is long, but very interesting: https://spectrum.ieee.org/xerox-parc That is _very_ good, and I too recommend it. Irritatingly, for such an otherwise-excellent piece, it contains two glaring, minor errors: "information-processing techniques office" should be 'Information Processing Techniques Office' (its formal name; it's not a description); "the 1,103 dynamic memory chips used in the MAXC design" - that's the Intel 1103 chip. > Markov's book, "What the Dormouse Said" ... goes into great detail > about the interplay between Engelbart's group at SRI and PARC. It's a > very interesting read; highly recommended. It is a good book; it goes a long way into explaining why the now-dominant form of computer user experience appeared on the West coast, ad not the East. One big gripe about it; it doesn't give enough space to Licklider, who more than anyone had the idea that computers were a tool for _all_ information (for everyone, from all walks of life), not just number crunching (for scientists and engineers). Everyone and everything in Dormouse is a descendant of his. Still, we have Mitchell Waldrop's "Dream Machine", which does an excellent job of telling his story. (Personal note: I am sad and ashamed to admit that for several years I had the office literally right next door next to his - and I had no idea who he was! This is kind of like a young physicist having the office right next door next to Einstein, and not knowing who _he_ was! I can only say that the senior people in my group didn't make much of Lick; which didn't help.) Still, get "Dream Machine". Noel

1 year, 10 months

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Re: "Hot Spot" High Performing Centres in Computing

by jnc＠mercury.lcs.mit.edu

> From: Larry McVoy > And the mouse unless my boomer memory fails me. I think it might have; I'm pretty sure the first mice were done by Engelbart's group at ARC (but I'm too lazy to check). ISTR that they were used in the MOAD. PARC's contribution to mice was the first decent mouse. I saw an ARC mouse at MIT (before we got our Altos), and it was both large, and not smooth to use; it was a medium-sized box (still one hand, though) with two large wheels (with axes 90 degrees apart), so moving it sideways, you had to drag the up/down sheel sideways (and vice versa). PARC'S design (the inventor is known; I've forgetten his name) with the large ball bearing, rotation of which was detected by two sensore, was _much_ better, and remained the standard until the invention of the optical mouse (which was superior because the ball mouse picked up dirt, and had to be cleaned out regularly). PARC's other big contribution was the whole network-centric computing model, with servers and workstations (the Alto). Hints of both of those existed before, but PARC's unified implementation of both (and in a way that made them cheap enough to deploy them widely) was a huge jump forward. Although 'personal computers' had a long (if now poorly remembered) history at that point (including the LINC, and ARC's station), the Alto showed what could be done when you added a bit-mapped display to which the CPU had direct access, and deployed a group of them in a network/server environment; having so much computing power available, on an individual basis, that you could 'light your cigar with computes' radcally changed everything. Noel

1 year, 10 months

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late 1990's servers vs R-Pi 5: quantifiable Performance vs Cost improvements?

by steve jenkin

An Old Farts Question, but answers unrestricted :) In the late 1990’s I inherited a web hosting site running a number of 300Mhz SPARC SUNs. Probably 32-bit, didn’t notice then :) Some were multi-CPU’s + asymmetric memory [ non-uniform memory access (CC-NUMA) ] We had RAID-5 on a few, probably a hardware controller with Fibre Channel SCSI disks. LAN ports 100Mbps, IIRC. Don’t think we had 1Gbps switches. Can’t recall how much RAM or the size of the RAID-5 volume. I managed to borrow from SUN a couple of drives for 2-3 months & filled all the drive bays for ‘busy time'. With 300MB drives, at most we had a few GB. Don’t know the cost of the original hardware - high six or seven figures. A single additional board with extra CPU’s & DRAM for one machine was A$250k, IIRC. TB storage & zero ’seek & latency’ with SSD are now cheap and plentiful, even using “All Flash” Enterprise Storage & SAN’s. Storage system performance is now 1000x or more, even for cheap M.2 SSD. Pre-2000, a ‘large’ RAID was GB. Where did all this new ‘important’ data come from? Raw CPU speed was once the Prime System Metric, based on an assumption of ‘balanced’ systems. IO performance and Memory size needed to match the CPU throughput for a desired workload, not be the “Rate Limiting Step”, because CPU’s were very expensive and their capacity couldn’t be ‘wasted’. I looked at specs/ benchmarks of the latest R-Pi 5 and it might be ~10,000x cheaper than the SUN machines while maybe 10x faster. I never knew the webpages/ second my machines provided, I had to focus on Application throughput & optimising that :-/ I was wondering if anyone on-list has tracked the Cost/ Performance of systems over the last 25 years. With Unix / Linux, we really can do “Apples & Apples” comparisons now. I haven’t done the obvious Internet searches, any comments & pointers appreciated. ============ Raspberry Pi 5 revealed, and it should satisfy your need for speed No longer super-cheap, but boasts better graphics and swifter storage <https://www.theregister.com/2023/09/28/raspberry_pi_5_revealed/> ~$150 + PSU & case, cooler. Raspberry Pi 5 | Review, Performance & Benchmarks <https://core-electronics.com.au/guides/raspberry-pi/raspberry-pi-5-review-p…> Benchmark Table <https://core-electronics.com.au/media/wysiwyg/tutorials/Jaryd/pi-les-go/Ben…> [ the IO performance is probably to SD-Card ] 64 bit, 4-core, 2.4Ghz, 1GB / 2GB / 4GB / 8GB DRAM 800MHz VideoCore GPU = 2x 4K displays @ 60Hz single-lane PCI Express 2.0 [ for M.2 SSD ] 2x four-lane 1.5Gbps MIPI transceivers [ camera & display ] 2x USB 3.0 ports, "RP1 chip reportedly allows for simultaneous 5-gigabit throughput on both the USB 3.0s now." 2x USB 2.0 ports, 1x Gigabit Ethernet, 27W USB-C Power + active cooler (fan) ============ -- Steve Jenkin, IT Systems and Design 0412 786 915 (+61 412 786 915) PO Box 38, Kippax ACT 2615, AUSTRALIA mailto:sjenkin@canb.auug.org.au http://members.tip.net.au/~sjenkin

1 year, 10 months

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