test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

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 | >+--------------------------------+-------------------------------------+ >

27 years

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. >

27 years

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 | +--------------------------------+-------------------------------------+

27 years

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

27 years

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

27 years

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

by spc＠armigeron.com

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27 years

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

by ethan_dicks＠yahoo.com

--- Sellam Ismail <dastar(a)ncal.verio.com> wrote: > On Mon, 19 Apr 1999, Ethan Dicks wrote: > > > I wish I had one of the stereo inspection microscopes... > > I have a similar device that was used for inspecting ICs. Its basically a > microscope with a fine adjustment platform... That's it. The one I'm thinking about has optional air bearings that can be clamped down with a foot pedal. You clamp the board into the frame, drag it around like a microfische, then lock it into place with the pedal. The field of view is adjustable, and can zoom in to entirely encompass a 1/4 W resistor or out to encompass several SMT ICs. > I assume you are thinking to replace the wire strand completely, and not > attempt to solder the two broken ends together? I need to get some pictures of this... Imagine a core plane... ||||||||||||||| --///////////////-- --///////////////-- --//XXX//////////-- --///XXX/////////-- --///XXX/////////-- --////XX/////////-- --///////////////-- --///////////////-- With the X's representing physically broken and/or absent cores. On my particular board, each bit of 4096 cores is a square approx 2" on a side (about 1/32" per core site), with the damage to two bits on the same edge of the PCB. I was originally planning on lifting the X and Y wires from one corner of the bit to be repaired, unthreading the cores only where necessary, and making any splices to the sense/inhibit wires at the edge of the core (as I belive there already are). If I scavenge wire and cores from the parity plane, I have more than enough raw material. If I attempt to sacrifice one bad bit for the other, I don't have the surplus wire (the X and Y wires must be preserved from edge to edge of the core PCB) I have just thought of another, more devious method, but on second thought, it would have to be clever indeed... Change the diode board such that the damaged bits are not both accessed at the same time (i.e. X32, Y16 on plane D4 is broken, but X32, Y16 on plane D3 is _not_ broken) and convert the two broken bits into two fields of 2048 cores each (and use the parity bit intact). It turns a 13-bit memory into a memory of 11 intact planes and two half-planes. I'll have to study the geometry to see if this is possible. Alternately, if the individual columns are intact, I could do 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. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

27 years

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

by allisonp＠world.std.com

<Do you have an opinion on how historically accurate is reasonable to <attempt? By this I mean that the parity plane (all by itself on a 3/4 <empty PCB) has no damaged cores. If I move the sense/inhibit wires from <its slot on the paddle boards, I can borrow them intact to act as one of <the damaged bits, I can then disassemble the more damaged plane (or perhap <the less damaged plane depending on where the damage is easier to get to) <and only have to repair _one_ plane. Your odds of success are much higher and it will be far less difficult. <In short: more like the original - disassemble the parity plane, removing <it from the stack, converting a 13-bit broken stack with 4 PCBs to a 12-bi <working stack, or, disassemble a broken plane, swap the data wires from it <to the parity plane, keeping all four PCBs inside the stack. The second <solution seems to make more sense from an effort and safety standpoint, th <first solution seems to me to be more "pure". In the era, if it were not used for parity (that wasn't common) then plane would then be considered "spare". Since an 8L was maxed (it could be hacked larger) as a 8kw machine that would be a nice box. Allison

27 years

FS: Russian computer

by adavie＠mad.scientist.com

I've been offered a Russian Computer - "So, the computer 'Elektronika MS-1502' is IBM-compotable, it likes IBM PC. It has a monitor, a memory volume 512 kb. It works with using a recorder, but if there is a device it can work with using a drive." This is probably too big for me, and sideline to my interests. If there's anyone on the list who would like to arrange to buy this machine from it's owner (it will be relatively cheap, I'm sure), then please contact me privately on adavie(a)mad.scientist.com and we can talk about your needs. You will, of course, have to arrange shipping out of Russia. I can handle payment for you. I have no financial or other interests in this machine, other than trying to find a buyer as a favour for this Russian gent who supplies me with calculators. Cheers A

27 years

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

by CLASSICCMP＠trailing-edge.COM

>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. Just wanting to point out that "display core" isn't a completely new phenomenon: Historically (going back at least 15 years), folks leaving the labs where I've worked - either retiring or moving on to other jobs - have been presented with core planes from machines that they worked with as "going away presents", frequently framed and behind glass. Ah, the memories!

27 years

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test-drb April 1999