test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

What if,... early PCs (was: stepping machanism

by allisonp＠world.std.com

<The RCA TV set design that RS used for a monitor for the model 1 was NOT <really adequate for 80x24 display. (YES, I've done it.) It could but the opto isolator used to keep the hot chassis and the video seperate wasn't up to the task. Bypassed and of course using an isolation transformer it was much crisper even at 80 cols. <Double density was NOT readily achievable in 1978. And the poor quality My dog, don't tell DEC that or intel. <> was SLOW. The Z-80-card in the Apple was significantly (and noticeably) <> faster. The two machines otherwise occupied about the same desk space, a Than the TRS80, every thing was faster. Next to my S100 CPM crate with a real 4mhz z80 and no wait state memory they were both slow. <> aside from the stupid, Stupid, STUPID choice to leave the Tandy machine' <> display at 16 lines of 64 characters (about half of what was on a 24x80, As it works 64wide was more useful for word processing than 32 or 40. Allison

25 years, 9 months

NEC APC III

by roblwill＠usaor.net

-----Original Message----- From: Fred Cisin (XenoSoft) <cisin(a)xenosoft.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Friday, April 09, 1999 1:51 PM Subject: Re: NEC APC III >With a few exceptions (and I doubt that the APC III would be one of the >exceptions), the 720K 3.5" can simply be cabled to replace the 720K 5.25". >The original design of it was intended to permit that. > Probably not. > >But that doesn't solve your need for a boot disk. In an earlier message, >you mentioned that your current boot disk is "Stoned". If so, a bit of >work with a sector editor might fix it. > Yeah - it's got the "Stoned" virus on it ( I think >Try to resurrect the 2.11 boot disk that you have. It's the HD - I can't access it - it starts to boot, says "MS-DOS 2.11", then comes up with an error (can't remember what, and the computer is at my school), and locks. -- -Jason Willgruber (roblwill(a)usaor.net) ICQ#: 1730318 <http://members.tripod.com/general_1> >MS-DOS 2.11 was the version that MICROS~1 provided for companies that >needed/wanted to customize for special hardware, such as 720K drives. >PC-DOS didn't support 720K until 3.20. >Previously (MS-DOS 2.00), sometimes only MODE.COM, and sometimes >FORMAT.COM, varied from one brand of machine to another. >But in 2.11, IO.SYS might be significantly altered. > >

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by edick＠idcomm.com

please see imbedded comments below. Dick -----Original Message----- From: allisonp(a)world.std.com <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Friday, April 09, 1999 7:18 AM Subject: Re: stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies) >On Fri, 9 Apr 1999, Richard Erlacher wrote: > >> Careful, now! He would have played hell trying to interleave memory >> accesses between an 8080 and the video refresh process, since its various >> cycle types were so different. It would have been worse YET with a Z-80! > >It was done though. The 6845 you generally talk to it's local ram through >it not around it. The H19 terminal did the latter. It was, indeed, but not when the Apple was designed, since the 6845 and 6545 didn't yet exist. >> The 6502 also allowed him to proceed with his own DOS and his OWN version of >> BASIC, without which he mightn't have gotten the strangle-hold on the >> personal-computers-in-business market. It's pretty hard to criticize his >> choices, however little I liked the result from the standpoint of seeing it >> as a tool, but his (and his partner's) decisions were definitely vindicated >> in the marketplace. > >It proved software was more important than hardware. The best cpu with no >software was still nothing. The z80 was maybe the best at the moment but >the 6502 was as versitile and plenty fast enough to make up for it's >limitations. There were many people who disagreed with that performance comparison. The two processors (I used them both extensively) were different enough that comparison and contrast was not easy. The Z-80 had many registers and a rich instruction set of which much was awkward and difficult to use. The 6502 had fewer registers and fewer instructions but they were amplified by addressing modes not readily available to the Z-80 user, particularly if his code was for CP/M which sort-of required you stick to the 8080-compatible instruction subset. The fastest 6502 available in 1980 was a 4 MHz processor which stroked memory for 125 ns almost every cycle in its typical application. The Z-80 had just that year become available in a "B" version (6 MHz) which stroked memory for slightly less than 3 clock ticks on a memory cycle and barely 1 (166 ns) on an unmodified M1 cycle. Having said that, and given (1) that the two processors executed code at about the same rate for the same memory cycle length (hard to prove or disprove) and (2) memory cost was more of an issue than system performance, hence the memory cost was used to set the rate at which the CPU operated, I'd say there's really no basis for comparing the actual performance of the two processors. >Likewise the trs 80 would prove lowercase and some more speed were very >desireable (based on the two most common mods!). The TRS-80 could have been put out with (1) an 80x24 display rather than the 16x64, it could have solidly supported double-density FD's (in the model 3) and it could have operated at about 4MHz rather than the 2.-something it used, and it could have switched in and out the ROM so it could run CP/M but for the greed of Tandy Corp. It would have cost them an additional $5 and change to put those features in their model 3, but they thought "well, we're going to sell a million of these . . . " and decided they preferred having the dollars. Had they gone the other way, they probably would have had the "personal computer" market all to themselves. They had a huge distribution network, a huge sales force, a huge service network, unlike any other microcomputer manufacturer of the time. Within a year, Apple owned the personal computer market, particularly with respect to businesses, even though Radio Shack had better packaging by the time the Model 3 came out. That was also about the time it became common to see the 80x24 displays, the 8"disk drives, the nearly 4MHz Z-80 running CP/M, the extra 16K memory, etc. on the Apple II. If Tandy had gone with the better design, which was on the table, there probably would be no IBM PC today. >Allison > >

25 years, 9 months

PDP-8/E PSU Debugging (was Q-bus pinout)

by allisonp＠world.std.com

<On another tack, the chassis I got did not come with any covers. I don't <know if this is "standard" or not. (I know the PDP-5 isn't designed to be They are missing then. The 8E had a cover as did the 8l and I think the 8I. <and so that has left me curious. I'm probably going to build a display rac <for it anyway with clear sides so that folks can "see" the innards without <risking getting fingers in them. Compare to a real top for vent slots as needed. <P.S. I'd like to thank Allison for relating the story of bringing up her <8/F since it inspired me to move forward on this project (code named <"FrankenEight" as it is a PDP-8 built out of parts exhumed from dead 8's o <other mysterious sources ...) My pleasure. I'm still working on mine to get it talking over the serial (I havent tried and I have to make a RS232 cable). Still they are a really fun machine and gobs of fun to hack new interfaces only. Omnibus 8s were the most hacked of the series as the bus made them easy to interface to and DEC make no secret of what is needed to do it. add to that with 8kw or more of core it's a machine that can do serious work if one chooses. Allison

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 5

by CLASSICCMP＠trailing-edge.COM

>On Thu, 8 Apr 1999 CLASSICCMP(a)trailing-edge.com wrote: >>I suspect when you say "MFM" you mean "all the soft-sectored data storage >>schemes descended from the original IBM 3740 (FM) standard", in which case >>you're right. >So, does that mean that those quarter-track schemes used for copy >protection on the Apple II could also be implemented on a PC or >Macintosh disk? The reason why I ask is because I've never heard of such a >practice. I think my statement is entirely unrelated to your question. The Apple ][ DOS 3.2/3.3 sector format, while it follows conceptually the same ideas as the IBM 3740 standard in that they are both ways of recording blocks of data on floppy disks and both encode the track and sector number in the header, is not by any stretch compatible with it. On an Apple Disk ][, you have complete control over the stepper phases, so quarter- and half-tracking is possible. (You can also blow out the Apple's power supply by switching the phases on and off at a certain "bad" rate, too!) The 34-pin Shugart SA400-style interface used for floppies in PC's doesn't allow half- or quarter-track stepping, though you could imagine trying to read or write something while rapidly stepping in/stepping out. If you want more information, I highly recommend that you read the Shugart SA400 interface documents, or the interface documents of a drive with a similar interface (i.e. the TEAC datasheets, which are also very complete.) I don't know of any documentation of the Macintosh 3.5" floppy interface. If someone could point me towards the relevant documents (or even the part numbers they claim to describe) I'd be quite happy! -- 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

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by allisonp＠world.std.com

<I grew up on the Z80, and for a time I thought that the 6502 was a Same here. <horrible little chip. But then I got to use a 6502 in the BBC micro and I I didn't have that opinion. It took a bit of getting used to having 256 registers that happen to be in the base memory page though. ;) totally revised my opinion of it. The 6502 instruction set was simple and <fairly clean. For high-level languages it was a fine processor (BBC basic <on a 2MHz 6502 was faster than similar BASICs on 4MHz Z80 machines). In the speed race they were close enough that how an app was structured and written had a greater effect. <No. Never forget the 3 magic letters 'IBM'. That's why the PC was <succesful. Technically there were plenty of better machines around at the <time, but they didn't have the appeal of coming from a company that <_every_ computer centre and DP manager had heard of. That is a fact! IBM legitimized the desktop machine even if it was inferior design. Allison

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 5

by CLASSICCMP＠trailing-edge.com

::Basically, yes. The track and sector are stored in the sector header of ::each sector, among other data. >In fact, most floppy disk systems work that way. Commodore GCR does that. >So does MFM, doesn't it? I suspect when you say "MFM" you mean "all the soft-sectored data storage schemes descended from the original IBM 3740 (FM) standard", in which case you're right. There are a few oddball hard-sectored drives that don't have any header at all on the data in each sector - hardware counters in the drive controller keep track of this stuff. Of course, once your head stepper starts stalling or your index sensor gets dusty, all sorts of nasty things happen with this scheme. And, even more rare, are some embedded-servo floppy disk systems where the location on disk is encoded in special formatting that cannot, in any reasonable way, be called a "sector header". -- 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

25 years, 9 months

[OT] <10 yo DG Aviion

by jeff.kaneko＠juno.com

Try the Newsgroup: comp.sys.m88k Good Luck! (You're gonna need it!) On Fri, 9 Apr 1999 15:50:45 -0500 "David Williams" <dlw(a)trailingedge.com> writes: >I know this system isn't 10 years old yet, but a company I use to >work for gave me a 88000 based Data General Aviion. I believe it is >an AV 4625 model if I'm reading the back right. DG's site only >talks about P-II and P-III based Aviions with nothing about the >earlier 88000 based ones. Anyone have any web site pointers or >info on these for me? I'm currently hitting each of the main search >sites without much luck. > >Thanks. > > >----- >David Williams - Computer Packrat >dlw(a)trailingedge.com >http://www.trailingedge.com ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

25 years, 9 months

[RANTISH] Programming Stupidity

by geoffrob＠stmarks.pp.catholic.edu.au

> From: Daniel A. Seagraves <DSEAGRAV(a)toad.xkl.com> > To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> > Subject: [RANTISH] Programming Stupidity > Date: Friday, April 09, 1999 10:15 > > > [Large progressive rant here, nevermind me...] First of several <snips> in this msg... >You guys think BASIC is bad? How about BASIC that automagically > writes bad Windows code for you! Sounds about right. Never tried VB myself, (well the beer, yes, that's ok) I have an assistant who is somewhat interested in using VB for righting apps. I had occasion to write a little PLC emulation for a dos box to replace a failing (and not Y2K compliant to boot) PLC that rings the bells at the school to announce change of class, lunch etc. It also controls the sprinkler system. Anyway, a couple days hacking around in Turbo Pascal 6 produced a simple little program that controls a few external devices on a time schedule via a $2 interface connected to the printer port. Runs on XT's and up, around 23k for the .exe file. Works fine. Just a text file with the schedule info in it. Too easy. My assistant thought that was ok, so he thought he'd try it in VB just as an exercise. At last count, it was something like a 650k exe file, needed at least 4 mb of ram, and he still hadn't found a way to get control over the bits in the printer port to let it actually do something useful!! He's still nibbling away at it, he's perssistant, so he'll probably make it go. Eventually. Been 6 weeks now though..... > This thing couldn't make optimized code > if Billy-boy's monopoly depended on it. Pity it doesn't depend on it. > On top of that, the bad code that it DOES generate doesn't even work. > We build the .EXE on a Win98 machine - Now it refusues to run on 95. Micro$oft producing non backward compatible software? Nah, couldn't believe that.... yeah, right. > Microsoft's wizard for making install programs for your software sucks worse. > It replaced some DLLs it wasn't supposed to have on our (one and only, thank > Goddess!) NT server, and NT crashed like you wouldn't believe. Oh yes I would. I just drop kicked the last of our NT servers. 2 years of tinkering and updateing and god knows what else and it STILL kept screwing up a database. It's now my workstation. Running 98. The family resemblance is still a pain at times, but at least it only gives ME trouble, not half the darn school.. > I'm gonna have a hell of a time putting THAT back together.. Doesn't sound like a fun weekend project. Best of luck. You'll need it. . On top of this, the > installer doesn't run under 95, either. It starts just fine, makes a pathetic > attempt at copying files, then blows up horrbibly with Error 0x16E. Wasn't > Billy saying they were supposed to make our error messages make SENSE? To Micro$oft Tech staff when you ring them at $25 a problem maybe. But I wouldn't even count on that. > an error message like that, a dialog box reading "YOU LOSE!" would be better. You've already lost if you have to run Windoze whatever. I'd switch to something more stable in a minute, but the sad part is that Windoze is everywhere, so we have to teach our students to use it and the apps that run on it, because that's what they will likely find in the real world.. > Another quote from my boss: > "In programming, it doesn't matter how well it runs or does it's job. The > bottom line is, 'can we sell it to someone?'" What planet is this guy from? Originally? Marketdroidia? He sounds like one of those funny creatures. > Is it just me, or is that just plain wrong? Please say it's not only me... It isn't only you. I think you have a couple of million mates globally. Minimum. Trust me on this. > I hate being alone, 'cause that means I'm right and everyone else is wrong. You are in absolutely no danger of that. Micro$loth bashing may become the all time greatest user participation sport of the 21st century. > Sorry for that, I just needed to vent. Do with it what you will... Just confirms much I already believed..... Cheers Geoff Roberts VK5KDR Computer Systems Manager Saint Marks College Port Pirie, South Australia geoffrob(a)stmarks.pp.catholic.edu.au

25 years, 9 months

Abort, Retry, Ignore, Fail? (Was: stepping machanism

by ethan_dicks＠yahoo.com

--- Sean 'Captain Napalm' Conner <spc(a)armigeron.com> wrote: > Oh. You're one of *those* ... okay. > > -spc (Hate Perl ... okay, so I'm a bit of a language snob 8-) I am presently paying for my classic computer hobby by crafting perl for 50+ hours per week at consultant's wages. I *love* perl! -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

25 years, 9 months

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test-drb April 1999