test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

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

by edick＠idcomm.com

You've got two tracks mixed up, I think. True, the Apple II was quite plentiful in 80, but not in businesses the way it was in 82-83. I even had several of them with people to man them as well. I hated the Apple but loved the 6502. In the meantime, I noted that the RS Model 1 was a piece of junk, and, in fact, so much of one that I never bought one, even for experimentation, and I had nearly every other sort of box around the shop. The Model 3 design my employer had contracted to him was paid for in late '81. I saw several of them in friends' houses, none of whom had bought them new, by the way, so they'd been on the market for a time in '82-83. We had a really terrible blizzard on Christmas of '82 here, and I saw one in a neighbor's house then. It was an early version but it was a model 3. I'm aware there were plenty of Apples around since the one which was wheeled in to the weekly 6502 Users' Group meeting by the chief guru was not even attracting a second glance. A lot happened in the early part of '81, i.e. Apple prices dropped for the first time, in an effort to retain market share >from the now increasingly available though not yet particularly attractive, either as a computer or as a budget item. There's some more imbedded commentary below, if you're interested. Dick -----Original Message----- From: Allison J Parent <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Saturday, April 10, 1999 5:59 PM Subject: Re: What if,... early PCs (was: stepping machanism ><The IBM entry into the PC market was in mid-1981, I think, and the Model-3 ><was rushed to get out ahead of it. The Apple-II exlposion wasn't quite ><underway yet, but the handwriting was on the wall. > >No. By then the apple and trs80 were common as house flies. In fact in >1980 we used Apples and TRS80s running a similar program for forcasting >as they were in wide use around the shop. They were both in the market >in terms of volumes nearing a 500k system each if not more by 1980. The model 1 was quite common, but the model 1 was in too many pieces to be of much interest to most folks. What's more, it was pretty weak-kneed. The model 3 held out hope, though that was later dashed when the model 3 turned out to be not much better. >the PC wasn't an impact until 82 maybe 83. Memories and events seem to >get compressed or expanded. I's even say the PC was not a serious >contender till mid 83. The initial impact of the PC was to get people to stop buying non-PC's for their businesses. They were extremely costly at first, and didn't have a few serious problems worked out. People had to mortgage their houses to buy one (a basic PC on the gray-market cost nearly $2k). >Allison >

26 years

OT: copying OS/2 Warp

by max82＠surfree.com

Hi, I managed to borrow a hard drive with OS/2 warp on it from someone. I want to copy it onto my own drive. How do I do this? I know that in DOS, I would do a sys command to make the drive bootable. There is no sys command here. What should I do? --Max Eskin (max82(a)surfree.com)

26 years

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

by pete＠dunnington.u-net.com

On Apr 11, 10:20, Richard Erlacher wrote: > Subject: Re: stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51 > I have to disagree with your comparison of the 2 MHz 6502 with a 4 MHz > Z-80A. My thought here is that the 4MHz Z-80 used in the conventional way, > had a memory cycle of 750 nanoseconds (3 clock ticks), while the 6502, at > whatever rate, again, used in the conventional way, had a memory cycle of > one clock tick. Now, some instructions involve several memory cycles, but > that was true of both processor families. What I often cursed, was that the > textbook application of the 650x core left memory available (idle) half the > time. That was a blessing up to a point (2.5 MHz to be exact) because it > allowed for DRAM "RAS-precharge." The Apple and others like it proved that > at around 1 MHz, the 6502's memory could be used for an entirely separate > purpose, e.g. video refresh. I wasn't talking about precisely 2MHz vs 4MHz, just a ballpark figure (as opposed to "about the same" or "about ten times" clock speeds). So, given the rest of your message, I think we're in broad agreement. BTW, BBC Micros have a 2MHz clock on the 6502, and interleaved video and processor access quite happily in 1980. The video took care of the refresh requirement. > I believe there are entirely too many subjective, architecture-related, > factors to allow an absolute comparison/contrast of the two processors. Agreed :-) That's why lies, damned lies, and benchmarks are so much fun :-) > In my "gut" I still believe the 4 MHz Z-80 is about > comparable to a 1.5 MHz 6502. Well, that's not very far from what I wrote, is it? I was just pointing out that although Allison seemed to imply that a 6 or 8MHz Z80 was much faster than a 4MHz(? I haven't got the original message any more) 6502, I believe that to be far from the case. -- Pete Peter Turnbull Dept. of Computer Science University of York

26 years

PICK OS

by max82＠surfree.com

I saw an interesting book at the library today about something called PICK OS. I didn't get to look through the entire book, but I read enough to see that it refers to directories as dictionaries. It seems to take a novel approach, but I know nothing about it. Haven't even heard of it. Does anyone here know more? Does anyone here have the PC version (mentioned in the book)? --Max Eskin (max82(a)surfree.com)

26 years

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

by edick＠idcomm.com

I have to disagree with your comparison of the 2 MHz 6502 with a 4 MHz Z-80A. My thought here is that the 4MHz Z-80 used in the conventional way, had a memory cycle of 750 nanoseconds (3 clock ticks), while the 6502, at whatever rate, again, used in the conventional way, had a memory cycle of one clock tick. Now, some instructions involve several memory cycles, but that was true of both processor families. What I often cursed, was that the textbook application of the 650x core left memory available (idle) half the time. That was a blessing up to a point (2.5 MHz to be exact) because it allowed for DRAM "RAS-precharge." The Apple and others like it proved that at around 1 MHz, the 6502's memory could be used for an entirely separate purpose, e.g. video refresh. At one point in time, I went to some lengths to demonstrate the relative performance capability, based on common applications, when the processors were placed in an environment in which the primary constraint on the processor's performance, hardware-wise, was the memory bandwidth. It turned out to be a rather difficult comparison, because of the lengths to which one had to go in order to utilize the memory bandwidth most effectively. The Z-80's most difficult aspect was that its memory cycles were of different lengths. The 6502 could be interfaced quite easily by using an asymmetrical clock, with a short Phase-1 (the period during which addresses and control signals change) and a relatively long Phase-2, which is the cycle when I/O to off-chip system-resources take place. This was straightforward until the system design was adjusted for DRAMs, which were the most common problem of that time. Both processors had problems with DRAM usage. The 6502, when its clock was tweaked to make DRAM access most time-efficient required, absolutely, that a cycle-stealing arrangement was used in order to support refresh. This meant extra hardware. However, the otherwise minimalist Z-80, which once was touted as supporting DRAMs by generating a refresh cycle from time to time, required extra hardware to modify its clock as well in order to allow for a long enough M1 cycle, and to allow enough time for the refresh to occur during its allocated window. This meant even more hardware. It turned out that all the things which the processors' designers had done in order to make the two chips "efficient" became a problem when I tried to implement each one in a way which was tailored to attain the most effective utilization from what was then the most costly system resource, the main memory. In any case, what I determined was that the Z-80, in spite of its complicated hardware requirement, was potentially the faster processor. This was based on a comparison of the two in what I then considered an application tailored to the most effective use of memory bandwidth. I also quickly concluded that the 6502 would outperform it in an application where memory demand was small enough to allow the use of SRAMS, because if the fastest Z-80 available at the time (1981) was handed memories fast enough to operate it at full speed with no wait-states, i.e. minimal hardware, the M1 cycle was still so short as to use the normal Phase-1 time of a 4 MHz 6502, the memory cycle of which was a single clock tick as opposed to the Z-80's three. I believe there are entirely too many subjective, architecture-related, factors to allow an absolute comparison/contrast of the two processors. Being mostly a hardware-oriented type, I find the analysis adequate to warrant the second conclusion above, though I've never been entirely satisfied with the comparison I made based on their relative speed in the execution of a BASIC program. The BASIC interpreters were different, and the programs had to be "fiddled-with" in order to make them both run. The difference was not overwhelming, so I've never been entirely comfortable with the concusion. In my "gut" I still believe the 4 MHz Z-80 is about comparable to a 1.5 MHz 6502. Back in 1980, the Z-80 was definitely the wisest choice if you had to settle on a single processor for carrying out useful business tasks, because the Z-80 could run CP/M which had LOTS of such "useful" programs, thoroughly debugged, most of which were entirely suitable for commercial use, and there were significantly fewer useful-work programs for the 6502, which was more popular in graphics-oriented systems because it could share its memory and because its instruction set was apparently better suited for moving icons around in a display memory as most game programs required. Dick -----Original Message----- From: Pete Turnbull <pete(a)dunnington.u-net.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Sunday, April 11, 1999 8:35 AM Subject: Re: stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies) >On Apr 11, 9:16, Allison J Parent wrote: > >> The point was apparently missed. Of course I can take a cmos z80 and >blow >> that out of the water using a 6 or 8 mhz clock. > >But because of the way the phases are used, a 2MHz 6502/65C02 is running at >roughly the same rate (for comparable operations) as a 4MHz Z80. > >-- > >Pete Peter Turnbull > Dept. of Computer Science > University of York

26 years

PR1ME 2550 Up and Running

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

---------- > From: John Lawson <jpl15(a)netcom.com> > To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> > Subject: PR1ME 2550 Up and Running > Date: Monday, April 12, 1999 10:11 > > > > Well... it didn't hurt as much as I thought it was going to.. > > I have just run "SHUTDN ALL" after two hours of playing with PRIMOS > (on a DEC LA120 running at 300 baud... s-l-o-w...). My first encounter with VMS was on a Vax 6310 using a Decwriter II at 300 baud. :^) > I rescued this system about two months ago, and finally got tired > of it taking up space. Nice work, a Pr1me is on my want list too. Can you post a pic on web site somewhere? > And, apropos of the Pick discussions, this machine has INFORMATION > loaded and running... haven't messed with it yet, tho..

26 years

Chicago trs-80s

by steverob＠hotoffice.com

On Tuesday, April 06, 1999 4:24 PM, Mike [SMTP:dogas@leading.net] wrote: > My vacation/computer-rescue-mission has come to a close and there is now a > big honkin pile of trs-80 6000 and 16b toys on my living room floor. :) > Several of them have broken this or thatsz but the first one I pulled, a > 6000hd 15mhd, booted into Xenix 3.0.1 I think (Microsoft '84). the 68k in > it crashed after about 20min of xenix frolicking. She's resting now. I'd > like cc and tcp for this if anyone can help me out? I 'm sure some parts > will be available as soon as I figure out what I have. Software, give me > software or give me death. > > ;) > - Mike: dogas(a)leading.net > Mike, Nice haul... A couple of weeks ago, I got a Model 2 and a Model 16 sans keyboards. Both machines had been in storage for a long time and were absolutely filthy. After careful disassembly, cleaning, and reassembly, the Model 2 returned to life. Another list member has located a keyboard for me (thanks) so, that one is complete. I haven't found a boot disk for it yet but, I'm sure it'll work just fine. Last weekend I opened up the Model 16 to see if it could be resurrected. The hard drive had been previously removed but it looks like everything else is there. After the ritual cleaning, I applied power to the computer and promptly smoked the floppy drive. One of the traces on the PCB lit up like a freakin Christmas tree. DAMN! I'm surprised it didn't blow a fuse or something. I haven't looked at the drive too closely so, I'm not really sure what happened there. If it is a power supply problem, the whole machine could be history. I'm hoping it was a problem with the floppy and didn't kill anything else. I have not been able to get a trace on the CRT and really don't have the enough tools to properly diagnose the problem. I did however notice the filament on the CRT was glowing and the cooling fans were running. I believe the fans get power from the 110AC primary and the filament could be >from an unregulated source. So, this doesn't totally eliminate a Power Supply problem. Can anyone tell me what voltages should appear on the PS connectors? Is there an easy way to determine if the processor is alive? Unfortunately, I don't have a scope or logic probe :-( If anyone can suggest a good source for a Logic Probe, I'll consider buying one? If I'm unable to get this thing working, I'll make the parts available. The case and CRT are in really good condition so, don't trash any of the Model 16 parts yet. Between us, we should be able to put another one together. Good Luck, Steve Robertson - <steverob(a)hotoffice.com>

26 years

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

by pete＠dunnington.u-net.com

On Apr 11, 9:16, Allison J Parent wrote: > The point was apparently missed. Of course I can take a cmos z80 and blow > that out of the water using a 6 or 8 mhz clock. But because of the way the phases are used, a 2MHz 6502/65C02 is running at roughly the same rate (for comparable operations) as a 4MHz Z80. -- Pete Peter Turnbull Dept. of Computer Science University of York

26 years

Speaking of Tandy & TRS-80 (was: Re: What if,... early PCs

by edick＠idcomm.com

There was another one I haven't seen in a couple of decades, called Allied. I once worked for a subsidiary of another Allied Electronics, so they must have been gone by then. Laffayette was a place where I bought audio components, e.g. speakers, crossover networks, passive radiators, grille-cloth, etc. Of course that was in the '60's . . . When the periodic table was easy to memorize, . . . let's see, there was air, earth . . . Dick -----Original Message----- From: Steve Robertson <steverob(a)hotoffice.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Saturday, April 10, 1999 9:01 AM Subject: RE: Speaking of Tandy & TRS-80 (was: Re: What if,... early PCs >On Saturday, April 10, 1999 10:16 AM, Charles P. Hobbs >[SMTP:transit@primenet.com] wrote: >> >> >> Does anyone remember a similar electronics store called "Lafayette"? They >> were a big chain, probably not nearly as big as Tandy Radio Shack though; >> I think they went under in 1980 or 1981 > > >I used to visit the Lafayette store in Ft. Lauderdale on a regular basis. >IIRC this was in the Early 70's. The store primarily had audio gear, HAM >equipment, and electronics components. Similar to the Radio Shacks of that >time. > >As a matter of fact, I still have a Lafayette Stereo Amplifier at home. I >used it for about 10 years then it quit working on one channel. Probably a >bad output transister. I just never got around to fixing it... > >I don't recall ever seeing any digital stuff in the stores. Of course this >was VERY early in the micro-processor development stage. > >Steve Robertson - <steverob(a)hotoffice.com> >

26 years

Parting out PDP-8a

by jeff.kaneko＠juno.com

Guys: I have discovered a PDP-8a in a scrapyard near my workplace. It has been outside for awhile; but if there are any salvable parts there, would anyone be interested? BTW-- How do I get the front panel off without breaking anything? Jeff ___________________________________________________________________ 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]

26 years

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test-drb April 1999