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101090 discussions

How scarce (valuable) is core for the PDP-8?

by ethan_dicks＠yahoo.com

--- Allison J Parent <allisonp(a)world.std.com> wrote: > <Any idea how to estimate the gauge? > > You'll have to mic it once the diameter is known you can look it up give > or take the enamel insulation. OK. Can do. > <What size nuts? > > Small, looked like #2. Can you translate that to a size? I can imagine the size of a #4 nut (I have several). I can't clearly picture how big the O.D. of a #2 would be. > ...A good material for this is hypersil commonly used for transformers. Used for the windings or the core laminations? On the topic of core size vs switching speed, I'd always assumed the drive to minaturize core was driven by the economics of memory density. I never considered memory speed. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

26 years, 8 months

Old computer books for laymen?

by ds_spenc＠alcor.concordia.ca

Hi, I was just looking at some of the books I've collected over the years (trying not to study for the exam I have tomorrow morning) and I spotted an old book entitled "Teach Yourself Electronic Computers". It's from the Teach Yourself Books series, (c)1962 The English Universities Press Ltd. Other books in the series include "Teach Yourself Algebra", "Teach Yourself Arithmetic", "Teach Yourself Geometry", "Teach Yourself Atomic Physics" (<- I kid you not!) etc, so it seems to be a book for the non-geek. The book is actually pretty good! What other early computer books were there for the reasonably non-geekish? -- Doug Spence ds_spenc(a)alcor.concordia.ca http://alcor.concordia.ca/~ds_spenc/

26 years, 8 months

CP/M as an RTOS (was Re: Dumb OS question)

by allisonp＠world.std.com

<Which is not so much because CP/M or DOS actually is an RTOS (they aren't) <but that they don't get in the way of the programmer. The programmer is <free to write his own interrupt handlers, and even a task scheduler. < <Note that this very feature that makes such an OS potentially usable for <real-time systems is exactly what makes them poor choices as platforms <for general-purpose computing. Too much code gets written that works aroun <the OS for no especially good reason. < <Note that a "proper" RTOS both doesn't get in the way, *and* provides <useful real-time services. Which some old timers to comp.os.cpm may remember the firestorm when I called CP/M a file system and not an OS... ;) Allison

26 years, 8 months

about cdroms...

by rlaven＠shore.intercom.net

I have a couple Panasonic cdroms that work with an ISA soundcard. Full set of drivers and installation software also. -rob-

26 years, 8 months

IBM Optical drive questions

by roblwill＠usaor.net

Does the 3431 need a special type of disks, or do they all use the same type of disks? -Jason -----Original Message----- From: SUPRDAVE(a)aol.com <SUPRDAVE(a)aol.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 9:29 PM Subject: Re: IBM Optical drive questions >the type 3431 is rewritable. >the 3363 is write once- read many. >

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

> >> One other thing I'd say, though, is that it's perhaps a bit questionable >> publishing code as yet because it will pollute the idea pool (no reflection >> on the quality of the submitted code) in that those who read it over (which >> I haven't for that reason) will potentially have their own approach >> influenced by seeing someone else's. > >Or they'll find ways to improve on it, which is what gives this whole >seemingly pointless exercise actual meaning and purpose. > >Sellam Alternate e-mail: dastar(a)siconic.com >--------------------------------------------------------------------------- --- Careful now! What I find better may not be better to you. It depends on your goals and outlook. I'd have liked it better if the initial phase had been without code listings and description of the approach chosen. Nevertheless, there's not much harm done. One who wishes to be entirely original doesn't have to peek. Dick

26 years, 8 months

z80 timing... 6502 timing

by edick＠idcomm.com

It's called an epiphany, Sam. You know . . . a moment of clarity . . . goodness knows one seldom gets to enjoy such an event. Dick -----Original Message----- From: Sellam Ismail <dastar(a)ncal.verio.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 4:09 PM Subject: Re: z80 timing... 6502 timing >On Mon, 19 Apr 1999, Richard Erlacher wrote: > >> I don't know why this has to be so complicated. There need to be > >My god! Dick just had a revelation!! > >Sellam Alternate e-mail: dastar(a)siconic.com >--------------------------------------------------------------------------- --- >Don't rub the lamp if you don't want the genie to come out. > > Coming this October 2-3: Vintage Computer Festival 3.0! > See http://www.vintage.org/vcf for details! > [Last web site update: 04/03/99] >

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

Your points are valid. I didn't intend building a new computer to be seen as a major construction project. It can be done with a processor, an oscillator can, a PAL, two memory IC's, and a UART, e.g. 16C450. As I said, it should take very little time, and the circuit could be built with both processors in the same circuit, perhaps with only one inserted at a time. It's not necessary, but it's the cleanest way to do the job if you want to participate yet haven't got a running system with one or both of these processors. By the way, if I were picking a processor for almost any job, these would be pretty far down the list, not because they're bad, but because others are so much more convenient. One other thing I'd say, though, is that it's perhaps a bit questionable publishing code as yet because it will pollute the idea pool (no reflection on the quality of the submitted code) in that those who read it over (which I haven't for that reason) will potentially have their own approach influenced by seeing someone else's. There ought to be a bit of time allowed to pass while folks contemplate the cosmic oneness and decide what they'll do. Dick -----Original Message----- From: Sean 'Captain Napalm' Conner <spc(a)armigeron.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 1:58 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) >It was thus said that the Great Richard Erlacher once stated: >> >> Well, I recall that someone said, a while back, that the devil's in the >> details. > > I'll say 8-) > >> What I'm trying to do is place boundaries around this problem for >> purposes of understanding its limits. Others who attempt to replicate your >> work on other processors will want to know these things. From your >> statement that the process produces a result of '*' for an invalid input, >> which, apparently would include negative values, non-integers, and integers >> of value 4000 or greater. If the input is presumed to be unsigned integer, >> that solves much of the problem. Now, you want to store the output in >> memory, presumably as ascii characters, presumably as a null-terminated >> string, and perhaps (optionally) echo it to the screen in the aftermath of >> your run. Does that sound like a reasonable thing to do? > > Yes. The actual code being timed is the conversion only, not the output >part, which is why the conversion is being stored in memory. > >> How do we tell this program what string of numbers to convert? Is this >> someting you want to put into memory as a null-terminated string of binary >> values, or would you prefer a single word for each value, with a null >> terminating the input array or a fixed string length? > > Well, if it's extended to read in a Roman number and covert it to binary, >then yes, you read from a NUL terminated string. That way, you can test >both sides of the program. But that's IF it's extended. I've yet to see >anyone else offer any code for the presented problem. > >> > I liked Sam's suggestion of ``printing to memory'' as a way to avoid the >> >complications of I/O in this, and if I didn't make this clear that the >> >conversion was to be stored in memory, I'm sorry. >> >> That should work. In fact, input could be done that was as well, placing >> the input in memory and then executing the program from a debugger or with a >> call from a HLL. > > Which is why I specified that the conversion program be callable as a >subroutine---to isolate the program from the specifics of the operating >system/monitor used to test it. > >> > I'm a software guy---building computers isn't exactly my forte. Besides, >> >if I say my code only requires 200 bytes of memory, and I can't figure out >> >how to build a computer with 200 bytes of memory (pretty easy for me 8-) >> >then that means I have 56 additional bytes to play with, maybe by adding >> >code to run blinkenlights or something. >> > >> > Besides, who wants to build a computer for this? Okay, except for Tony? >> >> That's the ultimate test, though, isn't it? > > If (and it's a big if) I build a computer, it's going to be based on a 32 >bit chip minimum (like the 68k or ARM). And it's not going to be for this >contest either 8-) > >> >> How is the 6809E relevant to the timing of the Z-80 and 6502? >> > >> > Nothing at all, except as an outside reference. That, and I don't really >> >know Z80 or 6502 code (nor do I have development systems for these chips). >> > >> Its certainly an outside reference. It may be a challenge for everyone to >> improve on it. . . We'll see, I guess > > I'm sure a cycle or two can be shaved off here and there, but I haven't >gone back over it myself. Heck, I've yet to see anyone comment on the code >itself. > > -spc (Or are we having more fun discussing the problem than working on > it?) >

26 years, 8 months

How scarce (valuable) is core for the PDP-8?

by allisonp＠world.std.com

<Any idea how to estimate the gauge? I know I'd need red and green enameled <perhaps another color like yellow? I also wonder what they used to insulat <the splices? It appears to be some kind of paint. You'll have to mic it once the diameter is known you can look it up give or take the enamel insulation. <What size nuts? Small, looked like #2. <Oy! The core circuit that I copied for my 12th-grade drafting project use <7.5VDC as the half-voltage. How much oomph would it take to induce a stabl <magnetic pattern in a steel nut?!? I would think that enameled insulation <would cook right off the wire. Keep in mind using say 30ga wire and the current could be in the several amps range as it's a pulse (a big one!). The total time would still be short. For a practical example a suitable ferrite could be used and there are plenty of suppliers. To do it with steel (not iron) nuts you'd have to do some pulse testing using one and a single turn of wire to find the switch point (push it with a bipolar narrow pulse). a second wire (a few turns) can be connected to a scope. Increase the drive to the first wire until you see it start switching. the BH switch point will be noticeable if the core has usable hystersis (fails otherwise). A good material for this is hypersil commonly used for transformers. I think the cores of the late 50s used that with a dimension of 50mils OD and about 5turns of 0.1mil thick material. Large cores are less critical and give a bigger kick as a responding signal. The penelty is that large cores switch slowly and have really big half select currents. The latter is not a problem with modern semis but in the late 50s early 60s transistors that could switch fast were also too slow and tubes didn't switch high currents well. mades doing core very hard. A tidbit of design history extrapolated from design of the TX2 (an Electronics Design article). Allison

26 years, 8 months

Repairing core (was Re: How scarce (valuable) is core for the PDP-8?)

by ethan_dicks＠yahoo.com

--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote: > I think I'd try to move the 'core mat' (cores + wires) from the parity > plane to the data plane and then repair the defective one. Not feasible. The X-Y wires run from one side of the PCB to the other and intersect two bits at a time, 64 cores each. It's not like a PDP-11 board (the only other one that I can look at right now). > Yes, it's a lot easier just to swap sense wires round, but that seems like > a kludge to me. I suppose I can start with disassembling the mat that seems easiest to get to, then decide on what to do with the parity bit from there. > I guess it comes down to : Do you need to _use_ this machine (when > swapping the sense wires round makes a lot of sense) or are you tryign to > restore it (when you make as few mods as possible). I have more than one PDP-8/L. I could always borrow a known good core stack >from an -8/L and stuff that in the -8/i. It's not as if our hobby depends on the provenance of spares as a "genuine" antique would. It's virtually impossible to guarantee that any particular part was *never* replaced over the lifetime of the machine. In order, I would like it to A) work, B) be aesthetic. A+B is optimal. A alone is acceptable. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

26 years, 8 months

DEC RA81 need quick answer

by healyzh＠aracnet.com

26 years, 8 months

Repairing core (was Re: How scarce (valuable) is core for the PDP-8?)

by cmcmanis＠mcmanis.com

At 03:27 PM 4/19/99 -0700, Sellam wrote: >Unfortunately, my rant is not going to stop the lame-o's selling it from >hyping it up as some cool collectable, and it's not going to stop the >techno-wannabees from buying it to stick on their wall. Recent experience, Them: "We have a PDP 8/F." Me: "Does it have any memory." Them: "We think so, there are six boards in the back." Me: (could be good, two core stacks..) "What are the numbers on the top?" Them: "Three are labelled G104 and the other three are labelled G227." Me: "No, you don't have any memory for this machine." --Chuck [For the record a 4K core stack in an 8 consists of a G104, G227, and H220 card. It was the H220 card that had the actual core "mats" on it. The H220 card is often "liberated" from PDP-8's as a trophy/display item.]

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

-----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 6:44 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) >> >> On Mon, 19 Apr 1999, Richard Erlacher wrote: >> >> > My best guess would be that off-the-shelf systems will be what folks use to >> > program for this "challenge" if anyone does it. There were so few tools for >> > homebrew or single-board 6502 systems that I doubt anyone with other than an >> > Apple or an OSI will be interested. OTOH, it will be someone running CP/M >> > or the like on a Z-80 who enters on the Z-80 side. >> >> That's a highly ignorant statement. There were plenty of other 6502 based >> machines, including the Commodore 64, VIC-20, the various Atari 800 >> models. It's an ignorant statement, perhaps, as my kids had all these "video toys" at one time or another, but not made from total ignorance. I intentionally have ingnored them because they had integrated video, which makes it less than trivial to assess whether you're getting all the available bandwidth and also makes it unlikely you'll find a compatible Z-80. Remember, it was the goal at the outset to make a comparison of the two processors unencumbered by "special purpose" features. >Don't forget the BBC micro either. IMHO it was one of the best 6502 >systems ever (although it lacked internal expansion slots, which was a >pity). The BASIC was the second-best I have ever used (beaten only by >BASIC-09), and it has a built-in 6502 assembler. > >Now there's a thought. There was an option for the BBC micro that was a >Z80 second processor (it's not that rare either), clocked at 4MHz (IIRC). >The BBC's 6502 clocks at 2MHz most of the time, slowed down to 1MHz for >some I/O. Now you can compare the Z80 and 6502's speeds in the same >machine, simultaneously. This might be an excellent system on which to make a real comparison. It might even be one on which to run that matrix multiplication problem I proposed last week. I thought that would be good because it would require the machines to keep running for a week or two. It also would really show the difference in terms of time since it's such a big job. Of course mass storage would be a requirement for that. Commodore also made a dual processor machine, didn't they? A Commodore-128, I seem to recall . . . The power supply from the thing now powers a nicad charger . . . Dick >-tony >

26 years, 8 months

core stacks

by jlwest＠tseinc.com

ISTR that if you had a core set for an 8 that was "mismatched", the hardware handbook had the procedure for using a scope to "tune" a set into the appropriate range. Jay West

26 years, 8 months

Repairing core (was Re: How scarce (valuable) is core for the PDP-8?)

by dastar＠ncal.verio.com

On Mon, 19 Apr 1999, Ethan Dicks wrote: > > I'd buy the core at $100, since that way you do have the working 8K for > > your PDP. Then I'd try to mend the broken core plane that you already > > have. If you fail, well you still have a machine with 8K in it (you'd be > > kicking yourself, I think if you couldn't fix the old core and couldn't > > still get a replacement). > > It seems the prudent thing to do, I was mostly just writhing about having > to pay double of what _I_ think it's worth. I was polling for a sanity > check to see if my expectations were unreasonable, or if the expectations > of those stick-it-on-a-bookshelf collectors were. I don't see what the big attraction to a core plane is. You stick it on your wall. Whoopee! Look at me, I have a core plane on my wall. Big fricken deal. Nobody even knows what it is anyway. From afar it looks like a black square. Closer up it looks like a piece of a window screen. Unfortunately, my rant is not going to stop the lame-o's selling it from hyping it up as some cool collectable, and it's not going to stop the techno-wannabees from buying it to stick on their wall. Sellam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------ Don't rub the lamp if you don't want the genie to come out. Coming this October 2-3: Vintage Computer Festival 3.0! See http://www.vintage.org/vcf for details! [Last web site update: 04/03/99]

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

This is a valid viewpoint, though I think, ultimately, the question to be answered pivots around which processor was potentially the most efficient of all its resources, including time. However, just the raw speed got a lot of discussion. In 1983, the 4MHz 6502 was "old hat" and the 8MHz Z-80H was readily available. However, AFAIK the peripherals for the Z-80H were not, and, in fact, I didn't ever see them. Somebody said they were out there at some point, but I've never seen them offered for sale. You could, of course, postulate that a given processor could be run at a given rate, whether it's true or not, but if you want a comparison of REAL parts running REAL code in a REAL environment, then you need something more than if you just look at what various vendors sold. Every design has compromises made, and, back in the early '80's, cost of memory was a factor, as was the assembly cost. In general, I saw lots of boards for lots of different processors designed to make the most efficient use of memory. Once we have a good idea of what you're trying to measure, you can make adjustments to the system variables. If you want to compute how fast a processor runs code with a given-speed-rated memory, you've got to design the most efficient memory interface you can and then adjust the processor clock for that. If you merely want to use a rate which trivially provides a baud rate generator with a convenient harmonic of the baud rate you intend to use, you can, I suppose design for that. I made the statement that it would take, at most, a couple of days to build a system which would allow straightforward programs to be run and thereby satisfy the requirement for a test system. I didn't really intend that people build a unique system just for this test. What I figured was that folks could look around the basement and see what they could find that would meet their needs. An old Apple-II would work if you compensate for its obtuse timing. Since they all seemed to have a serial console, almost any S-100 system would work. It's pretty hard to imagine how a limitation like your suggestion would apply. Newer processors addressed weaknesses in the older ones. One of those was ease of programming. In some cases, e.g. the 6809, the processor was designed with a regular instruction set and lots of addressing modes so as to make generating code easy. It didn't necessarily make it faster. I don't know how elegant such code will ultimately turn out to be. My best guess would be that off-the-shelf systems will be what folks use to program for this "challenge" if anyone does it. There were so few tools for homebrew or single-board 6502 systems that I doubt anyone with other than an Apple or an OSI will be interested. OTOH, it will be someone running CP/M or the like on a Z-80 who enters on the Z-80 side. That was why I thought a good simulator would be the best solution. Dick -----Original Message----- From: Bill Yakowenko <yakowenk(a)cs.unc.edu> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Sunday, April 18, 1999 5:21 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) >You'd normally expect that the winner of any such contest would be >the most recent processor, wouldn't you? So, if the cut-off date >was 1982, any processor that was released in late '82 should probably >beat any that was already available in 1979. Of course, if the 1979 >processor had a much faster version available in 1983 (like a higher >clock rate), that faster version wouldn't be legal with the 1982 cut- >off, because that wasn't around in 1982. > >So, I suggest that one way of judging cleverness of software hacks >is that they let an older processor beat a newer one. > >Judging that way, we don't even need a cut-off date. But anybody >coding for a 1999 processor won't have any way to win. > >Of course, then we need clear evidence when each processor became >available at each clock speed, and we can argue about when the chip >was *really* available (as opposed to being orderable, or just having >the spec available). > > Bill. > >

26 years, 8 months

Repairing core (was Re: How scarce (valuable) is core for the PDP-8?)

by ard＠p850ug1.demon.co.uk

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26 years, 8 months

z80 timing... 6502 timing

by edick＠idcomm.com

Yes . . . of course, I wasn't the one who thought a graphic display would be "nice" so one could see what was going on. Dick -----Original Message----- From: Sean 'Captain Napalm' Conner <spc(a)armigeron.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 4:10 PM Subject: Re: z80 timing... 6502 timing >It was thus said that the Great Sellam Ismail once stated: >> >> On Mon, 19 Apr 1999, Richard Erlacher wrote: >> >> > I don't know why this has to be so complicated. There need to be >> >> My god! Dick just had a revelation!! > > Now now ... > > -spc (No need to overly sarcastic here ... 8-) >

26 years, 8 months

Ancient disk controllers

by edick＠idcomm.com

I think I said some of the part numbers were badly managed in this set of products. It's quite confusing when you're ordering. I definitely ordered the board with the 1010 chip on it, knowing that it would physically fit my application, only to have the 1000-05 with the 8x300 and 1100 chipset arrive. These chips, (the 1100's) were really just msi parts easy to turn out while they tested the functions separately. The project was so far behind that they had to do something to recover costs. The 2010 chip wasn't available for quite some time. It was the version with the ECC capability built in. The 1010 was the one used in the PC, though, since it was available. By the time the 2010 became available, the RLL scheme used in the 5010 and other LSI's (from other vendors) became popular, and the ECC capability was ultimately not exploited via the 2010 in a PC application. Dick -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 3:33 PM Subject: Re: Ancient disk controllers >> The functional differences were that the -05 versions were physically >> smaller (5.75 x 8 inches) and didn't support the 8-inch drives. Someone >> else pointed out that the WD1000-05 uses the WD1010 integrated controller >> rather than the 8X300 and the WD1100 chip set. Since the main difference >> between the WD1000 and WD1001 is that the latter supports ECC, I would guess >> that the WD1001-5 must use a WD2010 controller. > >The WD1001-05 uses the older chipset (or at least mine does). It uses the >WD1100-06 ECC/CRC logic chip rather than (I guess) the WD1100-04 CRC chip. > >The WD1001-05 is based on the 8x300 + control ROMs, and not a WD1010. > >-tony >

26 years, 8 months

z80 timing... 6502 timing

by edick＠idcomm.com

While what you say is certainly true, the page-zero usage is not dynamic, so, unless your task is very large and complex, page zero usage is therefore under the coder's control. I agree with your observation that the rate of memory usage is a good indicator of the rate at which a processor gets work done. The 6502 shines in that respect, in that the internal operations are generally overalpped with the fetch of the next instruction, with a few notable exceptions. Generally speaking, I've chosen processors with foreknowledge of what the device's most frequent tasks would be. For example, I picked a 65C02 for an application for which my boss had expressed a profound preference for the Z-80. I had to prove to him that, for OUR task, the 65C02 had a couple of features we could use very effectively and which the Z-80 didn't offer. It's always case specific. Dick -----Original Message----- From: Dwight Elvey <elvey(a)hal.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 2:55 PM Subject: Re[2]: z80 timing... 6502 timing >"Richard Erlacher" <edick(a)idcomm.com> wrote: >> I don't know why this has to be so complicated. There need to be >> constraints in order to ensure a level playing field, but since there are >> two related objectives, (1) to find out which of the two processors in the >> title of this message is "faster" and (2) to generate the fastest code for >> them for comparison. > >Hi > I always have to wonder about the meaning of faster. >Although I like the 6502 for a lot of things and would >say that it is often faster than a 8080 for many things, >I also know that resources like page zero get used up >quickly. Once these are gone, things tend to slow down. > I think we will continue to see that, like in the past, >most processors with about the same memory access speeds >will do about the same amount of work ( same bit count ). >On chip cache has changed that some but that just makes >another category. I would say any processor was superior >to another on small benchmarks unless the numbers were >in the 5X magnitude or more. Large application are more >useful in comparisons but it is hard to come up with >enough cross platform examples to make meaningful judgments. > I've always said, one should stick with what makes you happy. >Dwight >

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

I reached a similar conclusion as well, regarding the approach, though I've specifically avoided "peeking" at the submitted code. I've yet to write a line of code, as I'm looking at writing a simulator which will "run" the code and keep track of resources used at the same time. This requires changing existing code, and, at least in my case, changing working code means more or less the same thing as starting over, since I've not looked at the good code for a long time. Dick -----Original Message----- From: Megan <mbg(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 2:38 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) > >>> You naughty _naughty_ programmer! That's not at all in the spirit of >>> the competition! >>> (Wish I'd thought of it.) >> >>shhhhhhhhhh! Now they'll try to plug up the look up table loophole. >> >>Y'know, if the rules don't SAY what it has to be, ... > >The rules don't say you can't... but you do have to account for all >memory used, for code and data... > >I've coded a version for pdp-11s, but since I have yet to test it >(though of course it will work first time :-) I'm not going to >post it yet... > >It takes up 62 words (132 bytes), uses 4 words on stack and 9 words >of pure data space... when I've actually gotten a chance to try it, >I'll be able to report how many instructions it takes to do the >conversions (I suspect '1' is minimum and 3888 is maximum). I don't >know how to check on number of cycles, though... > >The algorithm is pretty straightforward... converting to Roman is >the same as converting to decimal except that once you have the digit >for a given power-of-ten place, you convert *that*... > >I wrote it before looking at the code which was posted, and I suspect >the algorithm is similar with the exception that I don't have a lookup >table for the digits... > > Megan Gentry > Former RT-11 Developer > >+--------------------------------+-------------------------------------+ >| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | >| Unix Support Engineering Group | (home): mbg!world.std.com | >| Compaq Computer Corporation | addresses need '@' in place of '!' | >| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | >| Nashua, NH 03062 | "pdp-11 programmer - some assembler | >| (603) 884 1055 | required." - mbg | >+--------------------------------+-------------------------------------+ >

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

You bet! If there's a way for "them" to prevent you from beating them by being smart, they'll use it. I've been ground-ruled out a time or two when it looked like I might sweep 'em. Not in the coding arena, though. . . <sigh> Dick -----Original Message----- From: Fred Cisin (XenoSoft) <cisin(a)xenosoft.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 2:02 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) >On Mon, 19 Apr 1999, Bill Yakowenko wrote: >> Worrying about using 32K? For a simple little Roman Numeral pro... uh... >> <* light bulb goes on *> >> You naughty _naughty_ programmer! That's not at all in the spirit of the >> competition! >> (Wish I'd thought of it.) > >shhhhhhhhhh! Now they'll try to plug up the look up table loophole. > > >Y'know, if the rules don't SAY what it has to be, ... > > >OB_OT: A few decades ago, the Fremont race track used to have a 1200cc >aircooled "anything goes" class. Then they changed that to 1200cc >aircooled VW "anything goes" when I was 1/3 of the way through building a >car out of two Honda 600s. The Honda 600 resembles a Mini-Cooper, with >600cc 2 cylinder engine resembling a motorcycle engine, front wheel drive >with a trailer axle rear end; ~36HP, but ~45 with the Hawaiian head and >cam, plus ~10% more with some porting and polishing. By mounting an extra >front subframe where the rear used to be, it was 1200cc, 4 cylinder (2 in >each engine) >90HP, higher power:weight ratio than anything else in the >class, much cheaper to build than any of the serious contenders, 4WD, 4W >disk brakes, 4Wsteering (that REALLY takes some getting used to!) And >street legal. almost. >

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by mbg＠world.std.com

>I must be missing something here. 9 does NOT produce the longest string >< 10, 8 does. (IX v VIII), and 3999 isn't the longest string. > >3888 would seem to produce: > M M M D C C C L X X X V I I I \0 >which is 16 characters, including null. Which was the reason I said 3888 would probably take the longest conversion time with my code... >BTW, what comes after M? Is it correct that in Roman numerals there can >never be 4 consecutive occurences of the same letter? (The original Y4M >"bug"!!!) Actually, I checked this in an old encyclopedia I had... both forms IX and VIIII could be and were used... As for what comes beyond it, a bar over the letters (called a 'vinculum') meant 'x 1000'. So MMM and <bar>III</bar> (meaning a bar over all three letters) were both acceptable as indicating 3000. Two bars indicated 'x 1000 x 1000'. Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+

26 years, 8 months

How scarce (valuable) is core for the PDP-8?

by allisonp＠world.std.com

<sort of a "one from column A, two from column B" approach. As long as the <sense amps don't balk at the extra resistance of doubling the length of <of the sense wire, it could work. Not likely but ther eis anotehr totally different problem, asymetric noise pickup masking the cores switching. Your further ahead fixing the mat. The wire used should present little trouble as fine wire can still be had. As an aside to this with the lamers trophying the mats. Most often the mats are intact so someday they could again be spares. The best one I've ever seen was not real but instead used small nuts and three colors of wire to make a real looking mat of some 64 or 128 bits. I'd bet that with the right currents and timing you could even store data in it. Also anyone holding a "core" based machine knows enough to keep spares as that is expensive to fix when your precious machine tool is dead. Down time for those people costs more than the computer that runs it. I say this as I have two Qbus PDP11 core sets both known good. Trophy never. Maybe one day I'll power them up again. Allison

26 years, 8 months

Program Challenge (was Re: z80 timing... 6502 timing)

by edick＠idcomm.com

Please see embedded comments below. Dick -----Original Message----- From: CLASSICCMP(a)trailing-edge.com <CLASSICCMP(a)trailing-edge.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 19, 1999 1:56 PM Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing) >>This is a valid viewpoint, though I think, ultimately, the question to be >>answered pivots around which processor was potentially the most efficient of >>all its resources, including time. However, just the raw speed got a lot of >>discussion. In 1983, the 4MHz 6502 was "old hat" and the 8MHz Z-80H was >>readily available. However, AFAIK the peripherals for the Z-80H were not, >>and, in fact, I didn't ever see them. Somebody said they were out there at >>some point, but I've never seen them offered for sale. > >Of course, in the "real world", there are many other considerations >to systems design other than processor speed and the "my CPU can beat >up your CPU" arguments that are familiar to us from our schoolyard days >(and seem to continue interminably here.) > >This is, for example, why the number of 8051-descended CPU's that have >been shipped in the past 20 years is in the billions. (OK, very low >billions, but it's there.) (1 billion == 10**9, to not confuse the >folks who were educated outside the US of A.) > Yes, that's very true. The MC6809, for example, was touted as offering greater ease of programming, hence, less effort, hence better fit into applications with lower volume, among other interests. The 8051 is a completely different class of device, though. Its core is unquestionably the most widely used microcontroller core out there. There are those who claim that the PIC (Microchip) is going to take that market over are probably whistling into the wind, as although INTEL's share of that market has declined, the overall numbers from the dozen or so makers of 8051-core microcontrollers still dominate the market. The range of applications for which it is suitable is MUCH more comprehensive than that of nearly any other microcontroller, largely because there are so many variants with features otherwise needing to be added on and thereby increasing cost and circuit complexity. There are also some performance issues. There are some really quite fast versions of this guy. It has architectural features which reach back to its antecedent, the MCS48 family, yet its architecture supports operations with a fairly standard register set, and a fairly standard though minimal set of registers. It has several of these, as do some other micros, but one doesn't have to use the multiple register sets if it's not wanted. The 8051 is a single-chip microcontroller, though. It isn't really intended as the core processor of a more general purpose system though it's quite capable. The 6502 and Z-80 were intended as highly flexible processing units with external resources. Back when I was using the 6502 and Z-80, I used an 8748 or a 68701 or '705 when I needed a self-contained microcontroller. Dick >-- > Tim Shoppa Email: shoppa(a)trailing-edge.com > Trailing Edge Technology WWW: http://www.trailing-edge.com/ > 7328 Bradley Blvd Voice: 301-767-5917 > Bethesda, MD, USA 20817 Fax: 301-767-5927

26 years, 8 months

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