test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

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

by allisonp＠world.std.com

<Too bad it's wrong. It misses a few details bit it is essentially correct. Do research before you indite the document. <It makes it seem as if there was a box that was designated PDP-8/E and it <had a particular configuration that was retired until the introduction of <new box with the designation of PDP-8/F. This isn't supported by the eviden No. read the whole FAQ to get the full picture. that was an excerpt. <What really happened, and I have several independent confirmations of same <is that the PDP-8/E system evolved into the PDP-8/F in a series of steps. <Depending on the date code the machine was configured differently. Yes and sorta. the 8E was the large box and remained as the "big version". As a cost moderating measure the smaller 8m/f versions were created for more limited expansion and with a lower basic cost. <The evolution vectors were as follows: < Module updates - example M833 - M8330, M831 - > M8310 Bug fixes. early in the 8E life and nearly predating the later omnibus 8s. The original designs had poor margins and too much green wire. Even later ones have green wire. < Chassis updates - Long box, single OMNI BUS < Long box dual OMNI BUS < Short box single OMNIBUS Linear PSU on side. < Short box single OMNIBUS Switching PSU in Rear version replaced the really broken side mounted PS version. The switcher was not the best design as it was fairly new technology. < Front Panel Updates: Diode logic + 8v LAMPS Early 8Es only. Driven by manufacturability. < TTL logic + 6v LAMPS Bulk of production and the common verison in the 8E < TTL logic + LEDs in lamp sockets Never made, it was a field third party retrofit. < TTL Logic + LEDS 8F/M pannel later in design than the 8e v2. < PSU updates - Long linear PSU < Short linear PSU < Short Switching PSU (types A and B) Not updates litereally differnt products with overlapping production lives save for the two switchers. <At some point in this evolution some marketroid decided to change the name <from 8/e to 8/f. The OEM version of this platform was called the 8/m and Sorry no! the 8E remained in production and the 8f was the short 20 slot machine and aimed at lowering the cost for those that didn't need/want 38 slots. <included an optional limited function front panel (although all 8/M's I've <seen so far had the programmers panel but that's only about a dozen so who <can say) The 8M was a fairly standard menu machine with the limited function panel. It's options included a full function pannel (if you were a volume customer custom colors and board mixes). <I happen to have an 8/e that is: < Short box < 6v LAMPs plus TTL front panel < Side mount PSU That is not an 8E, it a frankenmonster in a 8m crate. <I recently picked up an 8/e chassis that had the dual OMNIBUS backplanes. That is an 8E. <It is this one that doesn't have a cover. It may have been mounted in a <desk, I don't know (it also didn't have a front panel but I can use my <other 8/E front panel with it) The 8e was the model with the long linear PSU on the side and the dual omnibusses. <My guess is that the evolution of the 8/E was driven by the introduction o <the 11/20 since these changes seem have occurred between 1970 and 1972. Al No. the two were entirely differnet development and had the common thread of newer low cost TTL available. <8/E's with date codes prior to 1970 appear to be the diode front panel <type, All 8/E's after 1972 appear to be either 8/F's or 8/Ms (until the 8/ <came out). 8Es were 1970 introduction. Parts will have datecodes up to a year older than that. <The 8/M and 8/F are primarily differentiated by different inserts/color <schemes, electrically they appear to be identical. The solder mask of the <front panel says "8/E" The same pannel was used for all. It was an assembly level options that set them apart. Since parts were swapable there were a lot of variations due to parts being moved as needed to maintain systems or make working ones. The omnibus series of PDP-8s were all driven by lowering costs and product improvements. Even the later 8As were KK8e cpus (m8330/8310/8320/8300). The actual 8A CPU (kk8a?) was a hex module. Allison

25 years, 2 months

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

by edick＠idcomm.com

Please see imbedded comments below. 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 1:44 PM Subject: Re: What if,... early PCs (was: stepping machanism ><It would be well to get the timelines aligned. The model 1 was of 1977 ><vintage. The model -3 was worked up in the late '70's before Apple got it ><juggernaut rolling. Radio Shack had a real chance to make the microcompute > >Model 1 (base trs80) was 1977 (mid year). I was part of the start up in >the computer depot repair and computer store startup. That's what I recall, as well. >The next machine did not ship until after august 1979! I was there up to >that point. Actually I think it was the 1980s(or 1980!) that the next >version of the TRS80 family shipped. 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. >The motly collection of parts... For years RS ment surplus parts in plastic >bags and the late 70s was sort of their weaning. Except the purchasing >mindset was there. > >If anything can be said... they were one of the few that didn't go broke >shipping computers. That's why they'd have been a force to be reckoned with if they'd ever shipped anything really decent. >Oh, and Apple shipped their machine the same year as the TRS80. so they >represent the state of the art for 1977 for cost vs tradeoffs. > >Allison > >

25 years, 2 months

Q-bus pinout

by cmcmanis＠mcmanis.com

Hello, is the Q-bus pinout on line? I've got an extender card and I'd like to know if it was compatible or not. Also a pointer to the printset for the PDP-8/e H724 PSU would be good, I've got one that is half dead (fortunately it is the back half so with the computer in the front half it runs!) --Chuck

25 years, 2 months

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

by CLASSICCMP＠trailing-edge.COM

> There should be >some plastic catches (or more likely the remains of same) on the PSU. I've found that most half-inch tape seals have latches which are quite amenable to being used as replacements for the original plastic catches :-). >BTW, one of the few pieces of poor design in this machine is that you >have to take the left side rackmount rail off the box before you can get >the PSU out. This means you have to take the entire (heavy) machine out >the rack before you can remove the PSU. If you use short 10-32x1/4" screws on the left rail, it's a lot easier to take the PSU out. (I thought everyone shortened these screws!) With the original screws (3/4"), it is possible to get the PSU in and out with the rail attached, but it is quite difficult and requires that the PSU be inserted at a rather awkward angle. -- 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, 2 months

source for foam filter material

by edick＠idcomm.com

At your local discount store, you should be able to find some fairly large scouring sponges, I've found that these work adequately as filters, provided you put a layer of porous cloth over the downstream side to catch the finest particles. If you're fortunate enough to find the really fine ones, the cloth isn't needed. These come in 1/4" thick postcard-sized sheets, which I usually cut up anyway, so give these a try and see if they meet your needs. Dick -----Original Message----- From: Lawrence LeMay <lemay(a)cs.umn.edu> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Saturday, April 10, 1999 2:33 PM Subject: source for foam filter material >Does anyone know where I might be able to buy some thin black foam filter >material, to replace the stuiff that was used on my Teral computers? >These systems have a large fan that draws air into the computer, and >the intake air goes through this very thin filter, in order to capture >large particles such as lint. > >After 22+ years, that foam is nothing more than dust. > >I would need something almost 5 inches wide, that i could then trim to >the proper shape. > >-Lawrence LeMay

25 years, 2 months

OT: copying OS/2 Warp

by SUPRDAVE＠aol.com

In a message dated 99-04-09 19:24:05 EDT, you write: > 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? > os2 has sysinstx instead. you'll need to boot from 3 os2 utility disks and then invoke the command.

25 years, 2 months

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

by allisonp＠world.std.com

<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. They were nothing like TANDY. I lived in the region back then, they were into electronics and audio. They were long gone by '79. allison

25 years, 2 months

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

by allisonp＠world.std.com

<It would be well to get the timelines aligned. The model 1 was of 1977 <vintage. The model -3 was worked up in the late '70's before Apple got it <juggernaut rolling. Radio Shack had a real chance to make the microcompute Model 1 (base trs80) was 1977 (mid year). I was part of the start up in the computer depot repair and computer store startup. The next machine did not ship until after august 1979! I was there up to that point. Actually I think it was the 1980s(or 1980!) that the next version of the TRS80 family shipped. The motly collection of parts... For years RS ment surplus parts in plastic bags and the late 70s was sort of their weaning. Except the purchasing mindset was there. If anything can be said... they were one of the few that didn't go broke shipping computers. Oh, and Apple shipped their machine the same year as the TRS80. so the represent the state of the art for 1977 for cost vs tradeoffs. Allison

25 years, 2 months

Heathkit H-8 questions

by allisonp＠world.std.com

<I saw a H-8 on eBay tonight. What year were these made? What could one <do with it? From the photo it has a 16 key keypad, numbers 1-9 and the <math symbols, decimal point, and 2 others i can't make out. What are <those 2 keys? I'm not trying to buy it, I wouldn't know what to do <with it even if i did. just curious. TIA. It was an 8080 machine with a oddball bus that was better than s100. The keypad on the front was a far friendlier substitute for the switches and lights. What can you do with it... it's a computer. not much I guess. ;) Allison

25 years, 2 months

PDP-8 lineage

by allisonp＠world.std.com

<>That is not an 8E, it a frankenmonster in a 8m crate. < <It was sold by DEC as an 8/E in the short box (granted its the 8/F box but <its the only 8 which I got from the original owner who still had the <paperwork. And on the back on the configuration chart it has the module <list and on the model number plate there is a generic tag market Model 8/_ <with a space that the same person who wrote the module configuration wrote <the letter 'e'. (and of course the front panel says 8/E and it has lamps <not LEDs). Anyway, the point is moot since I've got a long box and still n <hernia I could move the panel over to it :-) the 8m had lamps if the KC8E was installed. Only the 8F had leds. Also

25 years, 2 months

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test-drb April 1999