- test-drb@ccmp.vtda.org - classiccmp.org

Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

The classic example is an IC suspended over a PCB by means of the little pieces of #40 wire which connect it to the circuit. They're not always a terrible way to do things, and they've even been blessed by the analog weenies at NatSemi, but their use in modifying or even building circuits intended for some practical use is an abomination. Experimentation, well, OK, but to use it repeatedly? . . . Dick -----Original Message----- From: Bill Sudbrink <bill(a)chipware.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, March 31, 1999 3:42 PM Subject: RE: Kits vs ready-made (was RE: Rebirth of IMSAI) >> the shoddy technique (air-wires, etc) made for problems which couldn't > >I'll bite. What's an "air-wire". >

27 years, 3 months

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Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

Unfortunately, in today's climate ("NOTHING's MY fault!") people buy a kit with the assumption that the seller will provide whatever expertise is required to assemble it correctly. That was not the case 20 years back. This kind of handholding is frustrating and costly. A degree in engineering isn't sufficient qualification, either. Some of the crappiest work I ever saw while in the aerospace industry, was by fairly senior engineers. The excuse was that "it's not a deliverable," but often the shoddy technique (air-wires, etc) made for problems which couldn't readily be explained, but which didn't occur when a competent technician built the same circuit. 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: Wednesday, March 31, 1999 2:03 PM Subject: Re: Kits vs ready-made (was RE: Rebirth of IMSAI) >> I claim the other way around. Most kit suppliers have to spend _more_ on >> technical support because they have to help people who try kits too hard for >> them and expect the supplier to sort out their mistakes. > >On the other hand, I don't suppose total newbies (you know, the sort of >person who has problems inserting Disk 3 because the drive is already >full with disks 1 _and_ 2) would even attempt a kit... > >-tony >

27 years, 3 months

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More strange finds

by mbg＠world.std.com

>You can also use a Unibus host + a DW11B + a Q-bus backplane with CD >interconnect. The VSV11 was one of the devices _supported_ on the DW11B >(and the combination was called a VS11 IIRC). Good point... also, is there any support for it on uVaxen? >I have the VSV11 prints - I came across them earlier today when I was >looking for the VT11 stuff for Megan. I also found some 11/780 prints >(Unibus interface and WCS option prints, I think) I could use a copy of the prints... I have a VSV11 board set at home, but no joystick for it... 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, 3 months

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Rebirth of IMSAI

by allisonp＠world.std.com

<This would require a variable length or variable preset counter sourcing th <clock. The problem was knowing when it was going the generate an M1 cycle I used a shift register and an or gate. <counts. Either that or you'd have to look for the clock edge after the <appearance of the M1 strobe and KNOW it wasn't part of the interrupt <acknowledge. Neither was thrifty with logic, nor was it fun. M1 made it easy. the logic was if M1 then hod clock one cycle. <I had one friend whose NorthStar convinced me every time I saw it, that I <didn't want one. We were using CP/M, and you really didn't have even one <byte to spare in your measly 64K. His NorthStar only had 48K of memory <space, for some reason. Maybe it was because they'd mapped that region fo Funny mine has 56k to the base of BDOS. The trick is CCP and BDOS resides below the controller at E800h and the BIOS in the 4K at F000h. I also have a PROM burnt for F800 (trivial). The first banking scheme I did had mappable 4k pages in the F000h space. Very nice really. Later I went softsector using a uPD765 (I worked for NEC sooo...) and pulled the hard sector controller. Allison

27 years, 3 months

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ASR-33 Data Format?

by yakowenk＠cs.unc.edu

] Having secured a copy of Tom Pittman's Tiny BASIC on paper tape ] (autographed by the man himself!), I'm in the process of adding a ] teletype simulator to the COSMAC Elf simulator. It's a bit strange Without knowing anything much about ASR-33's in particular, but having done bit-banging serial stuff before, here are my best guesses. Do you have any delay on the recieving end that could make it miss the beginning of the next byte? The reason for the stop bit(s) was to give the reciever time to do something with the byte that came in, before the next byte started arriving. If the reciever needs more processing time, then the sender should include more stop bits. (In the real world, I've never heard of needing more than two stop bits.) Also, bits typically don't have any space between them. So, for instance, you should not return to '0' between sending two '1' bits. Between bytes, a reciever will typically watch for a falling edge to know when a start bit has begun. So if you return to zero even for an instant between two stop bits, the reciever may interpret that as the start bit of the next byte. And of course, between bytes, the line has to remain at '1', or risk looking like a start bit. Good luck! Bill.

27 years, 3 months

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Kits vs ready-made (was RE: Rebirth of IMSAI)

by Philip.Belben＠pgen.com

Sorry if this thread is old hat now - I've been having a hard time keeping up with the volume of traffic here recently. > Kits are often more costly than ready-built products because kit builders > fix their mistakes, while you can't expect the user of ready-made stuff to > fix your mistakes. Tech support is a necessity, yet most kit builders don't > need it. Tech support is what costs when you're selling a ready-built > product for the home computer market. This is strange. You are saying: Tech support is what costs. Kits don't need so much. Therefore kits are more expensive. ??? I claim the other way around. Most kit suppliers have to spend _more_ on technical support because they have to help people who try kits too hard for them and expect the supplier to sort out their mistakes. Kits generally have shorter production runs than complete units, hence less quantity discount / economy of scale. Finally, kits are generally better documented than complete units sold as such. And documentation costs a lot! Philip.

27 years, 3 months

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The move is accomplished!

by yakowenk＠cs.unc.edu

On Mon, 29 Mar 1999, Geoff Roberts wrote: >I hope it goes as well for me. (But it probably won't). To which Max replied: > If you expect to mess up, you'll probably find some way to do just that... > --Max Eskin (max82(a)surfree.com) In contrast, if you *don't* expect to mess up, you *definitely* will. The tricky bit is to foresee exactly what your mess-up will be, and prevent it. Bill.

27 years, 3 months

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Demos (was:Re: Rebirth of IMSAI)

by Philip.Belben＠pgen.com

> On Tue, 23 Mar 1999, Max Eskin wrote: > >> Perhaps, have the machines run the demos that they were running in the >> showrooms? [...] > Does anyone remember what the VIC-20 was usually up to in department store > displays? > > PETs? Pets I do remember. At least, the 8032. There was a screen that said in large letters "80 COLUMNS" which was manipulated in various ways using the (new) 8000-series ROM routines for scrolling in various directions, defining a virtual screen smaller than the real one, etc. Philip.

27 years, 3 months

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PDP-11/34A rebuild project Was: Re: Post-move diary

by mbg＠world.std.com

>The rightmost slots in a DD11-PK (11/34 CPU backplane) are special. No >way is slot 2 an MUD slot, for example. We are talking about the same >backplane, I trust... I found a couple of pages in the printset which show the board order for some standard configurations (11/04, 11/34 and 11/34a), and one of the pages clearly shows that slot 2 is a MUD slot. It just so happens that the second board of the CPU goes in it. I guess the printset could be wrong... but I'd like to believe I can trust it. 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, 3 months

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Z-80 M1?

by edick＠idcomm.com

Because the Opcode fetch cycle was shorter than other memory cycles, it was common practice to use M1* to insert a wait state. This added an extra clock tick to the length of the cycle, making it almost as long as normal memory cycles. That practice also set back DRAM design by a mite. It would have been smarter for the chip designers to cough up the MREQ* a bit sooner during M1* in order to make it easier to distinguish between opcode fetch cycles and interrupt acknowledg cycles. Hindsight is always 20-20 . . . 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: Wednesday, March 31, 1999 2:09 PM Subject: Re: Z-80 M1? >[Z80 M1 signal] > >> M1 signals the start of an instruction fetch or an interrupt cycle start. >> It's machine status to differentiate a opcode fetch from a data read or >> write. it serves other uses especially with the Z80 periperal chips. > >Sure, and if asserted along with IORQ/ it signals an interrupt >acknowledge cycle (Which is logical, as at least in Mode 0, it is going >to execute an instruction fetched from the peripheral chip). > >But I guess the question is _why_ would external logic need to know that >a memory cycle was an instruction fetch rather than a data read. In some >ways signalling a memory cycle that wasn't addressed from the PC would be >more use. > >I suppose some of the peripheral chips recognised things like RETI >instructions so they'd need to know that the appropriate bytes were being >fetched as instructions and not data. Is that the only common use, though? > >-tony >

27 years, 3 months

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Tandy 100 pile - could it be valuable?

by yakowenk＠cs.unc.edu

On Sun, 28 Mar 1999, Derek Peschel <dpeschel(a)u.washington.edu> wrote: ] Periodically I swing by Surplus Property here. It's very disappointing; ... mucho deletia ... Sounds like certain other surplus shops I know of. If it is publically accessible, make sure to periodically check their dumpster. And it is probably a good idea not to be obvious about it; even if it is legal, any adminstrators getting wind of it will imagine injury lawsuits, and put up barbed wire and security guards. Cheers, Bill.

27 years, 3 months

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Classic color video

by bill＠chipware.com

I recently acquired, and now have up and running, an OSI C4PMF. It has composite video output, 16 color. I have a mono composite monitor and the display is OK, some of the colors show up as grays (well, greens actually) but others show up in a sort of flickering effect. Video signals is one area in which my ignorance shines! I first tried to plug it straight into the 'video in' RCA jack on my color TV. It was trying to do something, but no dice. Next I RTFM. Says I need an RF Modulator. "I've got one of those" I think. I dig through my box of Timex-Sinclairs (BTW has just about everybody on this list, when they told their friends and family that they were collecting old computers, been given piles of TS-1000s?). I find one of those little silver boxes and hook it up. One problem, the box has the old 2-wire TV antenna cable on it, the TV has coaxial antenna in, but I dig through my junk box and find a converter. Switch the TV to channel 3 and... still no good. Pop the back off the little silver box... it looks like it's just a switch. No other components in the box except for a couple of torids that the wire loops around. Is this box an RF Modulator? Is there some simple circut I can build >from Radio Shack parts that would convert to (NTSC I guess?) 'video in' on my TV. Thanks, Bill Sudbrink

27 years, 3 months

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Sorry, I posted a personal note to the list.

by kstumpf＠unusual.on.ca

I took the time to copy Colan's address and was planning on replacing the list address with Colan's and the rest is history. I'm really sorry. ---------------------------------------------------------------------------- ------------------------------- Kevin Stumpf * Unusual systems * www.unusual.on.ca +1.519.744.2900 * EST/EDT GMT - 5 Collector - Commercial Mainframes & Minicomputers from the 50s, 60s, & 70s and control panels and consoles. Author & Publisher - A Guide to Collecting Computers & Computer Collectibles * ISBN 0-9684244-0-6 .

27 years, 3 months

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t3c meeting

by kstumpf＠unusual.on.ca

Hello Brian, > > >I've raised the idea with Larry about a get together sometime on the >weekend after easter, lunch on me. > > >Colan > > Please excuse me too, but the timing is incredible. I'd like to have a BBQ in Kitchener in June. Not an organizational event, but just a social gathering of computer collectors. I was thinking of supplying the propane and iced tea and everyone contributing a few dollars for burgers, etc. We could meet around noon on a sunny Saturday afternoon in June and be bidding each other farewell by supper time. My "ware"house is large enough and convenient enough to hold the gathering. Please bounce that idea around also. What does t3c stand for? Yours in good faith.

27 years, 3 months

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Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

I don't remember what my point was or where the original notion that kits often cost more that ready-made, except that if one sells kits, the folks who buy them usually are competent and capable of fixing their mistakes. If you sell both kits and ready-made, not only do you have to offer tech support to the buyers of the ready-made product because you attract a wholly less competent buyer, but a goodly share of your kit buyers are peoplenot otherwise competent hoping to save a few dollars by messing the kit up and then having your tech support people nursemaid them through the repair. I remember that the kits I bought were accompanied by a parts inventory, an assembly drawing, a schematic, and an extensive set of assembly and checkout instructions, none of which accompanies today's PC-oriented products. You're lucky if you can figure out from any of the paperwork, who built the product and whom to call if you have a problem. The kit, of course, has to be properly documented. In today's ready-made environment, little documentation accompanies a product, though even that's not often used. Today, the kit would be offered not so people can enjoy building it, though that's an added benefit for those who really do enjoy it, but rather to circumvent FCC restrictions if that's still possible. The FCC testing would keep almost any of the products of this sort with which I became familiar back in the '70's off the market, first because they would knock out TV reception for a considerable distance, and secondly because these volume in which they were built would not cover the cost of the testing. If one took the films used twenty years ago for, say, an S-100 board set and made it available as a kit, i.e. with all the IC's, passives, and hardware, it would cost quite a bit more than it did back 20 years ago. That's because of inflation and because labor to buy, stock , kit, and document the thing would cost more, not just the difference for inflation, but really more, because the labor cost buys less these days, and because people simply expect more than they once did. It would also make sense to silkscreen as much of the documentation for jumper and switch settings onto the board so the user can't lose it. Though the old IMSAI boards I have are solder-masked, the old ALTAIR ones are not. That could complicate building a kit as well, particularly for folks not experienced with soldering. You're certainly right about the cost of documentation. That's why it's hard to recommend LINUX and some of the rather excellent pieces of software work which have been done in conjunction with it. The documentation is generally quite poor, and always several generations out of date. Frequently one finds places where key words and phrases have been left out . . . words like "not" . . . Dick -----Original Message----- From: Philip.Belben(a)pgen.com <Philip.Belben(a)pgen.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, March 31, 1999 10:04 AM Subject: Re: Kits vs ready-made (was RE: Rebirth of IMSAI) > >Sorry if this thread is old hat now - I've been having a hard time keeping up >with the volume of traffic here recently. > >> Kits are often more costly than ready-built products because kit builders >> fix their mistakes, while you can't expect the user of ready-made stuff to >> fix your mistakes. Tech support is a necessity, yet most kit builders don't >> need it. Tech support is what costs when you're selling a ready-built >> product for the home computer market. > > >This is strange. You are saying: Tech support is what costs. Kits don't need >so much. Therefore kits are more expensive. ??? > >I claim the other way around. Most kit suppliers have to spend _more_ on >technical support because they have to help people who try kits too hard for >them and expect the supplier to sort out their mistakes. > >Kits generally have shorter production runs than complete units, hence less >quantity discount / economy of scale. > >Finally, kits are generally better documented than complete units sold as such. >And documentation costs a lot! > >Philip. > > > > >

27 years, 3 months

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ASR-33 Data Format?

by bill_r＠inetnebr.com

Having secured a copy of Tom Pittman's Tiny BASIC on paper tape (autographed by the man himself!), I'm in the process of adding a teletype simulator to the COSMAC Elf simulator. It's a bit strange because the 1802 code does bit-banged serial i/o, and my simulated teletype has to do bit-banged serial i/o back at it. At least initially, rather than hack all the 1802 code to run at a faster baud rate, I'm simulating 110 baud with my "teletype", so most of the time the emulated 1802 and the emulated teletype sit there waiting for each other to send data. It's _almost_ working, but I'm getting some odd results that I think may stem from an incomplete understanding of the way the ASR-33 and others of that vintage send and receive data. I'm testing with some code in an article about interfacing the Elf to a Teletype, so I'm pretty sure the Elf code is correct. I'm using 110 bits per second, no parity, 8 data bits, one low (logic 0) start bit, and one high (logic 1) stop bit. It seems to like the data low-order-bit first, but I have nothing that confirms that how it should work. I'm also working from the assumption that the data bits, the stop bit, and the start bit are all the same length. Also, I'm assuming that the "110 bits per second" includes the time for the stop and start bits, but I'm not sure of that either. It seems to be transferring characters; I get consistent hex values for each character I send to the Elf, but they seem to usually be either shifted left or right by one bit, or they have the high bit set when it shouldn't be. It feels like I've either added extra bits or am missing some in there somewhere. Can someone who knows this information for sure clear these things up for me? -Bill Richman (bill_r(a)inetnebr.com) http://incolor.inetnebr.com/bill_r - Home of the COSMAC Elf Microcomputer Simulator, Fun with Molten Metal, Orphaned Robots, and Technological Oddities.

27 years, 3 months

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Timonium Hamfest

by tomowad＠earthlink.net

>I didn't see any of the Apple II stuff that Tom saw Probably because I bought them all. :-) >I did see 3 TRS-80s, all model 1, level 2, one with expansion box and 2 >floppy drives I missed those (probably would have purchased them, as I don't have much TRS-80 stuff). The only TRS-80's I saw were a $50 Model 100 and a $25 CoCo II. >Nothing else of interest... no TTYs, nothing S-100 (I rummaged through a number >of boxes of PC cards and assorted junk, just to be sure), absolutely >nothing Ohio Scientific. I saw a TI Silent 700, one of the portable models. I've _never_ found any S-100 or Ohio Scientific at any Hamfest around here. Tom Owad

27 years, 3 months

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Z-80 M1?

by arfonrg＠texas.net

I have never really understood the purpose of the M1 pin or cycle. Can anyone in simple terms explain it's purpose? ---------------------------------------- Tired of Micro$oft??? Move up to a REAL OS... ######__ __ ____ __ __ _ __ # #####/ / / / / __ | / / / / | |/ /## ####/ / / / / / / / / / / / | /### ###/ /__ / / / / / / / /_/ / / |#### ##/____/ /_/ /_/ /_/ /_____/ /_/|_|#### # ###### ("LINUX" for those of you without fixed-width fonts) ---------------------------------------- Be a Slacker! http://www.slackware.com Slackware Mailing List: http://www.digitalslackers.net/linux/list.html

27 years, 3 months

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bringing up an 8f...

by allisonp＠world.std.com

Well I powered the PDP-8f tonight and guess what? The PS is toast. I'm not much surprized either. Anyhow this one has a hard short of the kind when power is turned off the room light dim. Next step is to pull it out of the case and inspect and meter it for where the short is. Anyone with a schematic? This one is the rear mounted style with the cover that says, do not operate with cover removed for more than 15 minutes. Don't need the whole prints but only some things verified. Is this a low voltage switcher? Or linear? Is there more that one secondary on the transformer? Both large fans are gone too. the small PS fan is not tested yet. but it's stiff so that ones gone too. fans I have plenty of. Did I mention it was a clean one? ;) Allison

27 years, 3 months

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sad tale

by jim＠calico.litterbox.com

I was at my grad school yesterday, and visited the guy I did vaxcluster admin work for back in 1992-93. A sad experience, I'm afraid. Turns out my guess was wrong, the LN-O3s appear to be long gone, first of all. Second, they've migrated away from DEC equipment in general to a mix of NT and IBM AIX machines. The cluster I used to run, from the sound of things, has been reduced to only the server, the vax 4000/500, and it's off maintenance contract and scheduled to be pulled from service within a year. *sigh* Sic transit gloria Vaxen. A silver lining - if I keep after the guy, I'm thinking he might take me up on my offer to haul it all away for free. What I'd do with an 8350, 5 microvaxen and so on in addition to the 4000/500 (assuming they still have all the members of the cluster) I dunno, but if it comes up, I'll figure it out. :) -- Jim Strickland jim(a)DIESPAMMERSCUMcalico.litterbox.com ----------------------------------------------------------------------- Vote Meadocrat! Bill and Opus in 2000 - Who ELSE is there? -----------------------------------------------------------------------

27 years, 3 months

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Collectors list

by emu＠ecubics.com

Hi, ---------- > From: Don Maslin <donm(a)cts.com> > To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> > Subject: Re: Collectors list > Date: Wednesday, March 31, 1999 1:09 PM > > On Wed, 31 Mar 1999, emanuel stiebler wrote: > > > Hi all, > > > > Because i feel so lonely here in Denver, i got the idea of collecting a > > list of the listmembers. I simply want to see, in what areas you can meet > > people an what they collecting. > I think that zip codes are only useful for mailing. I thought about the zip code because you could sort the list very easy. And in the sorted list, you could easy find out, if anybody is near you. But ok, we can do a list with: country/state/city name interests so it still can be sorted. thanks all for your attention ;-)) cheers, emanuel BTW, i don't like to see real email-addresses here, i get enough spam already :-((

27 years, 3 months

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bringing up an 8f...

by CLASSICCMP＠trailing-edge.com

>> Anyone with a schematic? This one is the rear mounted style with the >> cover that says, do not operate with cover removed for more than 15 >> minutes. Don't need the whole prints but only some things verified. >At the risk of sounding like a complete and utter moron, why can't you >operate for more than 15 minutes with the cover removed? Because without the cover the airflow from the fans won't properly go over the components needing to be cooled. Remember, unlike PC-clone cases, where the fan on the back provides minimal cooling to the contents of the box, most non-PC-clones actually have fans to ventilate the guts. Tim.

27 years, 3 months

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8" floppy formatting

by lemay＠cs.umn.edu

I need to reformat a bunch of old 8" floppy disks for use on a Terak system with single sided single density shugart drives. Terak's cannot format floppies (well, actually I recall a program that could format, but it required special hardware and DSDD drives on the Terak, which I dont have). I will attempt to format the floppies on a Cromemco Z-2 system with DSDD drives. Assuming this even works, I'm wondering if I should buy a tape eraser and use it on the floppies before attempting to reformat them. I need the 'standard' SSSD format, which I think is 26 sectors, 128 bytes/sector. Any suggestions on the best way to proceed will be appreciated. I need to backup the old floppy disk software I have before time or accidents cause me to lose some of it forever. -Lawrence LeMay lemay(a)cs.umn.edu PS: I'm looking into obtaining permission to distribute the software and manuals and operating system that were developed here at the University of Minnesota, Minneapolis.

27 years, 3 months

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ASR-33 Data Format?

by Philip.Belben＠pgen.com

> Bzzzt! > > In asychronous communication, the rated speed of the channel in bits per > second *includes* the start, stop, and parity bits. > > The ASR-33 did transmit (and receive) 110 bits per second, even though > only 70 (not 80) were usable data. I think the figure is 80, not 70, for the usable data. (I won't get into the baud/bps argument). Ten whole characters. The ASR-33 doesn't do anything to the msb, except have an option to generate parity there in the _keyboard_. You can send ten 8-bit characters per second, 80 bits of data, to a TTY and all 80 bits will appear on the punch. You can read ten characters per second from the punch and all 80 bits will be sent down the line. It's only typing on the keyboard in which usefulness is restricted to 70 bits. Philip.

27 years, 3 months

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FS: Zilog ZDS 1/40 Devel. System

by cfandt＠netsync.net

Hey gang, still sorting out stuff I really cannot keep over here at the new house. This is an item I must part with: Complete ZDS 1/40 Development System with Z80A emulator pod. Dual 8" floppy drives. About 1977-'78 vintage. Runs RIO (the OS), BASIC and of course, a Z80 assembler/linker. Have software floppies and docs. Zenith Z-19 terminal is part of this system. I haven't used it for at least 12 years or so. System is in two sizeable desktop cases each 19" wide x approx. 17" deep x 10" high. The main unit weighs about 30 lbs (I'm guessing as I don't have the scales over at the old house where the syst. is still at), the dual 8" floppy drive unit is maybe 45 lbs and a separate batch of s/w and docs should be around 20 lbs or so. The Z-19 should be around 25 lbs I think. Packed away somewhere in a box in the new library upstairs is the s/w and docs. Gotta dig them out when I get a bit of time tomorrow I hope. I could then send a list to the interested parties. Also, I gotta dig out that Z-19 and check it out. You wouldn't believe how much work I've got yet to get that old house cleared out yet :( (I at least took time yesterday to discuss Megan's 11/34A as it's just as important for me and my own 34A's troubles plus I *really* needed a rest) Anybody want to offer anything for this plus shipping from zip 14701? Will be shipped in three or four cartons. Let me know. Thanks much. Regards, Chris -- -- Christian Fandt, Electronic/Electrical Historian Jamestown, NY USA cfandt(a)netsync.net Member of Antique Wireless Association URL: http://www.ggw.org/awa

27 years, 3 months

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More strange finds

by mbg＠world.std.com

>Thanks for the info on the "Toaster", I'll fit a fuse into it and see if >I can fire it up, it looks fairly clean so it should be ok. I might go >back and see if the rest of the VSV11 is still around, there was a lot of >DEC gear hanging around, mainly terminals. Please pardon me if this is incredibly obvious, but I just wanted to point out that to use the VSV11, you need a qbus-11 in a backplane with sufficient Q/CD slots to handle it. A BA23 is not sufficient, nor is a BA123. You'll need a BA200 series or H9642 to make it work (or a BA11-N with the proper backplane -- H9275?) 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, 3 months

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bringing up an 8f...

by mbg＠world.std.com

>Well I powered the PDP-8f tonight and guess what? The PS is toast. Sorry to hear it... >I'm not much surprized either. Anyhow this one has a hard short of the >kind when power is turned off the room light dim. Next step is to pull >it out of the case and inspect and meter it for where the short is. oo... room lights dim? ouch... >Anyone with a schematic? This one is the rear mounted style with the >cover that says, do not operate with cover removed for more than 15 >minutes. Don't need the whole prints but only some things verified. I have some print sets for the 8/e, 8/f, 8/m family... but they may be pdp-8/e specific. I'll check for you... 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, 3 months

3
2
0 0

Decwriter II

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

-----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, 31 March 1999 6:38 Subject: Re: Decwriter II >Do check which version board you have, they have totally different >layouts.... Print is very faint, but H7728D is what it looks like. >Actually, are you sure the output of that flip-flop is stuck (check it), >or could the problem be further on in the logic? I can look at where that >line goes if you need me to. I'll check that and get back to you. Thanks. Geoff Roberts Computer Systems Manager Saint Mark's College Port Pirie, South Australia. Email: geoffrob(a)stmarks.pp.catholic.edu.au ICQ #: 1970476 Phone: 61-8-8633-8834 Mobile: 61-411-623-978 Fax: 61-8-8633-0104

27 years, 3 months

2
1
0 0

PDP-11/34A rebuild project Was: Re: Post-move diary

by mbg＠world.std.com

>I should have the prints for it (and for the VR14) somewhere. I fixed a >couple of VR14s a few years back - interesting things to work on. Watch >out for that EHT PSU can - it's a mains transformer + voltage doubler and >is quite capable of killing you. EHT PSU? You mean the VR14? Yep, I'll be avoiding that one until I absolutely have to touch it... >> Two other important cables to root around for in the box, which go >>between the M8266 and M7859, are two 10-conductor flat cables P/N >>70-11411-1D. When >Those aren't _essential_ unless you're like me. They enable the >'maintenance mode' of the frontpanel - single-step microcode, etc. Some >manuals recomend against leaving them in the machine (presumably to >prevent confusing lusers), but I've never had a problem. I guess I am like you... if the machine has some capability, I want it available to me... I'll have to look at it again to try to figure out what you're talking about as to where the cables go... >They're easy to make from 10 way IDC header sockets and ribbon cable, >though. That's good to know... >I believe you can put an MUD or SPC card in slot 5 if you don't have the >cache. I can't remember what happens if you don't have the FPU - either >slot 3 is also an SPC slot (I think that's the case) or you move >everything left one slot (Which I think is not the case). In the backplane I have, everything except for the first slot and the last slot is a MUD. (Confirmed by the decal on the inside of the chassis and by the printset). 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, 3 months

2
1
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PDP-11/34A rebuild project Was: Re: Post-move diary

by mbg＠world.std.com

>I forgot to mention this, and it's important if indeed you do not have >the 11/34A assembly printset: the 20-conductor flat ribbon cable polarity >is swapped around when plugged into the prog. console panel. The pin >one/blue stripe side of the ribbon cable is *not* connected to the board >connector pin one. It's correct when plugged into the M7859. I'm assuming >cables are not now connected between the panel board and the box. If they >are still conn. then you'll see what I mean. (Why did DEC do this? Was it >because of a mistake which was not considered important to fix or was it >because of board artwork considerations to make mfg simpler/cheaper?? >Doesn't seem like something DEC would let by.) I hadn't noticed the swap... I thought the connector was keyed, so you can't put it in wrong... I don't know why DEC might have done this... BTW - it turns out I do have the 11/34a printset... >I'm much less of a guru than anybody as I've never had my hands on *real* >PDP-11 hdwr until last summer/fall. I'm actually in the learning mode but >have done enough fiddling and have about half the resources I need to be >sort of maybe a little knowledgeable. (Is that vague enough?? :) That'll >be proved when I start working with the list for help on getting my own >11/34A system running. Maybe my experiences, and the documentation of same, will help... (I hope we're not putting everyone else to sleep with it) >Let me know what tech mans and printsets you need. Then I'll see what I >can do to copy missing ones for you if indeed I have them. However, I >lack several myself or have apparently too-early versions so may not >completly fill-in your needs. As I mentioned, I have the 11/34a printset. I have not yet found the VT11 printset, nor have I found an LPS printset... Do you have these? (Does someone else have these?) 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, 3 months

3
2
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Swapmeet Strategies

by jpl15＠netcom.com

I think this is suitably on-topic for The List: I have been a swapmeet/junk store/surplus rat all my life. There are three or four swapmeets I attend regurlarly. Here in SoCal, the TRW hamfest is probably the best-known, but there are three or four others just as 'good'. At TRW, there are two distinct periods of activitiy which I have deemed the "Shark" phase (at the opening of the meet to Buyers) and the "Vulture" phase (at the end of the meet when the Junk gets Cheap) with a relative lull in the middle hours. BUT: A secret to getting a few 'scores', is to be around when the sellers are gathering/unloading/standing around in the dark waiting for the coffee truck to set up. If you can finagle your way into that area, early before the hordes of buyers arrive... in my experience that is where some of the best deals are made. At TRW, the sellers are 'staged' into a lage parking lot first, then allowed into their spaces a line at a time from the staging area. People start getting there about 5:30 or so, and the sellers move to their spaces at 7:00, then the meet opens at 7:30. In that staging area one can have first pick of a lot of the goodies.. Your Milage May Vary. Cheers John

27 years, 3 months

1
0
0 0

Ohio Scientific (Yes again!)

by SUPRDAVE＠aol.com

In a message dated 31/03/99 11:46:35 Eastern Standard Time, george(a)racsys.rt.rain.com writes: > Where did they all go? > > Does anybody have any idea where all the Ohio Scientific machines all > ended up? > > We have a few collectors on this list with a few machines but it sure > seems like more were made than our collections account for. > > I'm especially curious as to where all the C2-8p systems ended up. > > My inventory: > 1 C2-4p shell > 1 C2-4p Working > 1 C4p Bad RAM > > None of my systems had floppys with them... > > Anybody have any idea about Production numbers? I'd never even heard of an OSI machine until I picked up a C1P complete with marketing materials/schematics and bare circuit boards 3 years ago. Were they really that popular? I know someone at work that heard of them, but that's it.

27 years, 3 months

2
1
0 0

Floor tiles

by Philip.Belben＠pgen.com

> On Mon, Mar 29, 1999 at 01:43:40PM -0500, William Donzelli wrote: > >> Are European floor tiles for computer rooms 2 feet square, like those >> found in the U.S., or are they smaller? > > They are 60x60 cm. Yes, I think that's a common size. But the tiles in the office where I am sitting right now are 50x50cm. I also think that the structural tiles (don't know what they are really called) used for raised floors in computer rooms are also often 50cm square. (Not 50cm^2, though!) Philip.

27 years, 3 months

1
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Moving sale - many old books, computer hardware & software, magazines, etc.

by tiger＠silcom.com

Hello everyone. I have a lot of old computer hardware, software, books, and magazines which I'd like to sell before I move long distance in about a month. Over the last few months I've posted on Usenet and tried eBay with only moderate success. With moving day approaching and too few sales lately to justify the time, I'm about to give up and donate the majority of these items to the local charities who are fortunately willing to take most of my stuff. This means that any sales need to be resolved within a couple weeks. As this is the classical computer list I hope some people here might have interest in this type of old computer stuff. The majority of it is from the 1980s. The computers I have the most stuff to the least stuff for sale are: - IBM compatible - Commodore 64/128 - Apple II series/IIGS - Amiga - Atari 8-bit - Macintosh - TI-99/4A Very briefly I have: - BOOKS - a couple hundred computer books, programming books, electronic data books, and technical books (a lot of reference books are for Apple and Amiga, such as the Addision-Wesley series). Also a few math and physics textbooks. - SOFTWARE MANUALS - a couple hundred manuals without the disks for things like Borland Turbo products, Microsoft C/C++, Visual Basic, DBase, Autocad, etc. - HARDWARE - Commodore 128 computers, disk drives, many printers for Commodore specific and IBM compatibles, old monitors, cassette units, etc. - SOFTWARE - a LOT of software for the first 4 computers in my list above. For IBM I have mostly old applications, for Commodore mostly games, and for Apple & Amiga mostly applications and development software (APW, Merlin, Manx C, etc). There's a misc handful for the other 3. - MAGAZINES - a variety of magazines, mostly for IBM and Apple. PC Tech Journal, Nibble, Video magazine, etc. I could be convinced to dump some ancient PC Magazines and Compute's for the right price, but I was planning to keep those (unless I'm floored by the movers' estimates this week). - LASERDISCS - a handful of older titles, mostly at $9 each. - GAME MANUALS - I have almost 50 computer game manuals without disks. I was asking $9 for all of them, but I'd just throw them in for someone who's buying a lot. Please look at my lists and feel free to ignore the prices and make reasonable offers. My main criteria are I have to get enough money to make the transaction worth the effort and the amount needs to be reasonably close to what I think my charitable deduction will be worth. If you can come by Santa Barbara, California, and pick up a lot of stuff in person we'll work out a really good deal. Please send email to tiger(a)silcom.com if you're interested in anything. All of my lists can be found at: http://www.silcom.com/~tiger Thank you for your time.

27 years, 3 months

3
2
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Western Digital PASCAL microengine / p-system.

by drbilling＠ucdavis.edu

Concerning p-machines: >At 08:19 AM 3/19/99 -0500, John Ott wrote: >> >>I am interested in learning more about p-machines. Does anyone have >>some references, faqs or web sites that would help? > >I have an aging UCSD Pascal history page at my online computer museum: ><http://www.threedee.com/jcm/>. I'd love to get a Microengine someday. > >- John I vaguely remember that the Western Digital p-machine microengine was based on the chipset that Western Digital made for DEC to build the LSI-11/2, just different microcode. Does anyone actually have some documentation for this board or board set? I have also been scanning all of the WEB sights that have information about UCSD PASCAL and obsolete and disappeared computers and I find no reference to Sage Computer Technology of Reno, NV. They made the Sage II/IV systems that came with UCSD PASCAL installed. They were M-68000 based systems and probably ran other operating systems too. Anybody remember them? -- Dean =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Dean Billing Phone: 530-752-5956 UC Davis FAX: 530-752-6363 IT-CR EMAIL: drbilling(a)ucdavis.edu One Shields Way Davis, CA 95616

27 years, 3 months

4
6
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Z-80 M1?

by edick＠idcomm.com

That's the signal which tells the world that the Z-80 is starting a new instruction cycle and is currently fetching the opcode. It is also the cycle during which the refresh occurs. The Z-80 asserts IOREQ* and M1* concurrently in order to signal a vectored interrupt acknowledge is in progress and that the peripheral should drive its interrupt vector address onto the bus. Aside from this last functon, I've never seen any particular need for a processor to let me in on the fact its opcode fetch cycle was in progress. It is helpful, I guess, if you're hand-toggling a program into the processor as it executes them, though that's not how it's usually done. Dick -----Original Message----- From: Arfon Gryffydd <arfonrg(a)texas.net> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, March 31, 1999 7:36 AM Subject: Z-80 M1? >I have never really understood the purpose of the M1 pin or cycle. Can >anyone in simple terms explain it's purpose? > >---------------------------------------- > Tired of Micro$oft??? > > Move up to a REAL OS... >######__ __ ____ __ __ _ __ # >#####/ / / / / __ | / / / / | |/ /## >####/ / / / / / / / / / / / | /### >###/ /__ / / / / / / / /_/ / / |#### >##/____/ /_/ /_/ /_/ /_____/ /_/|_|#### ># ###### > ("LINUX" for those of you > without fixed-width fonts) >---------------------------------------- >Be a Slacker! http://www.slackware.com > >Slackware Mailing List: >http://www.digitalslackers.net/linux/list.html

27 years, 3 months

1
0
0 0

about...

by rlaven＠shore.intercom.net

I have several Connor 40 Mbyte hard drives. -rob-

27 years, 3 months

1
0
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NorthStar Dimension

by dastar＠ncal.verio.com

Remember a while back I mumbled something about finding some documentation for a NorthStar Dimension computer which I suspected was PC compatible? Well, I found a short review of it in the 1985-86 Edition of _The Peter McWilliams Personal Computer Buying Guide_. This is the book that has all those keen Victorian-style illustrations throughout the book. They turn up regularly at thrift stores and the like. The NorthStar Dimension is reviewed on page 78. 8088, 256K, MS-DOS, multi-user system. The system was modular. You would buy a CPU, and could hook up to 12 terminals(dubbed "work stations") to a single CPU. The "work stations" could apparently run MS-DOS apps. Sellam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------ Don't rub the lamp if you don't want the genie to come out. Coming in 1999: Vintage Computer Festival 3.0 See http://www.vintage.org/vcf for details! [Last web site update: 02/15/99]

27 years, 3 months

1
0
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followup

by edick＠idcomm.com

Well, now that I've gotten to where, if I smoked, I'd go have a cigarette while waiting for a 450MHz processor do to something, I'm almost ready to wire up a 4.5" x 6" card with a Z80-H and a couple of hard disks of that generation and fire up CP/M just to see how slow it seems now. I haven't fiddled with one of these old timers in years. Years ago, I said that computers wouldn't be fast enough for me until everything I typed for it to do was done by the time my finger left the return key. Well, we're there now, and they're still a mite sluggish to me . . . 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: Tuesday, March 30, 1999 4:47 PM Subject: Re: followup ><I guess it's fortunate there was only one DMA process going on at the time ><else it might have been real sticky figuring out what had been overwritten ><already.. If you were doing a read in order to do a write, using DMA, you ><might actually get tangled up. Fortunately that showed up while the vendo ><was debugging his code, so I didn't have to deal with that. > >Multiple DMA streams are doable too though hard to apply usefully. > ><That's quite so. Fortunately one wasn't required to load data at the ><granule size, but rather at the sector size, so you could get by with a rea ><of a 1K sector. Of course you had to read it before you could write it, s ><you had to wait for the next revolution of the disk. All this went by so ><fast, and, since I didn't run big databases requiring sorts to and from ><disk, I didn't perceive much delay, as it only takes a few revolutions to ><load up a program. So each drive had six logical drives on it. > >I have. Running a pair of drives and using ramdisk and my own smartdisk >system. That was the speed order as well, the smartdisk system was fasest >as it hard its own CPU and DMA channel to processor ram using hidden cycle >stealing plus caching to 4x physical track size. That and a 6MHz z80 and >dust flew. > ><This all sounds like it could be fun if, for example, you're running it al ><on classic and unmodified hardware. I'm not sure I'd want to try to earn m ><living that way, though. > >it's more fun on current hardware like 33mhz Z180s and it's still in use >in odd pockets here and there. I don't (never did) make a living off it. > >Allison >

27 years, 3 months

2
1
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Rebirth of IMSAI

by edick＠idcomm.com

That sort of thing was common. I never figured out why they didn't just load the code into RAM from the ROM, then make the ROM go away. Eventually, that was the method of choice. 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: Tuesday, March 30, 1999 5:05 PM Subject: Re: Rebirth of IMSAI ><I said 'ROM' because on a number of machines, it was just a few TTL chips ><that gated C3, lobyte, hibyte onto the data bus on the first 3 fetches ><after reset. > >Most used a mux and jumpers to fake a 3byte rom with the first byte >hardwired as C3h (jmp in 8080/8085/z80) and it was jammed on the bus for >boot and only then. another approach was to on power up map rom to loc 000 >and also F800h and then disable the mapping after the code was running up >high. Plenty of tricks to fake that. > >Allison >

27 years, 3 months

1
0
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Museums

by mbg＠world.std.com

<> I was thinking that the important part of all this is just to get <> SOMETHING started. Don't worry about all the costs of going all out to <> create a computer museum type organization. Just start out with what yo <> can to begin with. Even if that means a garage party every month among <> local collectors then that's a good start. From there, people will get >Therein lies the essence of getting going. Inspired comment. >Right now Megan and I seem to be the most voluminous collectors on the >eastern MA area and we are close to each other. To get something going >needs critical mass greater than two. Hmmm... does anyone remember 'progressive dinner parties'? You'd get a group of friends interested in dinner, and you'd go from one house where you'd have one part of the meal, to another where you would have the next part, and so on... What about something like that for viewing collections... It would have to be a limited number of people at any one time, obviously... I'd definitely have to clean up... :-) 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, 3 months

11
14
0 0

Rebirth of IMSAI

by edick＠idcomm.com

-----Original Message----- From: Allison J Parent <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Tuesday, March 30, 1999 5:05 PM Subject: Re: Rebirth of IMSAI ><It was always somewhat of a nuissance dealing with the Z-80 because of the ><way it presented its interrupt acknowledge, which was a combined I/O and M ><cycle, as long as the I/O cycle, but with M1. That meant, in my case, tha > >All instuction fetch cycles were short, INTA cycle had an extry cycle added >for interrupt resolution in the supporting chips. > >To get around the short M1 cycles I'd use a tiny bit of logit to stutter >the clock to the chip (slip a cycle) for M1 only. This results it running >generally faster and still using slower memory. This would require a variable length or variable preset counter sourcing the clock. The problem was knowing when it was going the generate an M1 cycle in advance, since the instructions were, generally of different clock cycle counts. Either that or you'd have to look for the clock edge after the appearance of the M1 strobe and KNOW it wasn't part of the interrupt acknowledge. Neither was thrifty with logic, nor was it fun. I've done lots of clock fiddling with various processors, and I admit from the get-go, that the Z-80 was the least fun in this respect. It had so many timing requirements that, once you varied from the beaten path, you were going to use too many parts. Why would one want to replicate the bus timing state machine just to improve it a bit? The reason for using a Z-80 was that you could use CP/M for your development environment. I even had a scheme wherein I took my target system and connected its processor to my CPU socket via a cable or other arrangement, just so I could use CP/M. If it hadn't been for that one, I'd never have put a Z-80 in anything. 6801's had more features and required less hardware, and their clock was symmetrical so you could share memory if that was desirable. It's a real pain with the Z-80. That's true of the 8085 as well. I always preferred the 6502 and 68xx parts for useful work. Unfortunately they didn't have the support of really useful OS. (well, . . . maybe on the Apple, but I never got much use out of them until I put in a Z-80 card.) ><This same protocol made it unwise to try to use memory mapped I/O, since the ><cycle length of an I/O cycle differed from that of a memory cycle. > >I used to do it all the time and like I posted earlier the NS* disk system used MM-IO very effectively. > I had one friend whose NorthStar convinced me every time I saw it, that I didn't want one. We were using CP/M, and you really didn't have even one byte to spare in your measly 64K. His NorthStar only had 48K of memory space, for some reason. Maybe it was because they'd mapped that region for I/O. > >Allison >

27 years, 3 months

1
0
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More strange finds

by dburrows＠netpath.net

> >Thanks for the info on the "Toaster", I'll fit a fuse into it and see if I >can fire it up, it looks fairly clean so it should be ok. I might go back >and see if the rest of the VSV11 is still around, there was a lot of DEC >gear hanging around, mainly terminals. > It is a 3 board set(sometimes 4 if it has the optional second memory). I am on the road right now so I don't have the # offhand but they have a ribbon (40 pin I think) between them. They are quad wide Qbus boards but are also used in Unibus machines with a Unibus to Qbus converter. If you think they might still have the rest of it I will look up the board # and backplane # when I get back. I have 1 I use routinely along with several for supporting customers. Be sure to get the Cab Kit and the Joystick. Dan

27 years, 3 months

1
0
0 0

Computer busses....

by edick＠idcomm.com

please see imbedded comments below. 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: Tuesday, March 30, 1999 4:31 PM Subject: Re: Computer busses.... >> >>You've hit most of the important signals. One I'd add, however, is a data >> >>bus disable, and perhaps an address bus disable as well. This would allow >> a >> >>front panel or other bus mastering device to steal cycles under certain >> >>circumstances. >> > >> >Why wouldn't BUS REQUEST work? >> > >> It would only work if BUS REQUEST were not a request for negotiation. If >> you do have a bus negotiation handshake, then it might not work simply to >> asser BUS REQUEST because you may want to "jam" data in to certain locations >> while the processor is doing most of the work. CPU places addresses on the >> bus, you, by means of your front panel, want to put different data there. >> You float his data bus, and drive it yourself while he creates the strobes >> in his normal timing. Likewise, you might want to redirect his data flow, >> hence you float his address bus, driving it yourself, while the CPU >> generates normally timed transaction control signals. It's an obscure point >> but I've seen it done for whatever reason on several occasions. > >I see what you're saying, but it's not that common to want to do that (if >the CPU doesn't have access to the main memory, it'll execute NOPs or >RST38's depending on how the bus is pulled, for example, which might not >be that useful). Admittedly the PERQ rasterop machine did something >similar (got the CPU to generate addresses and start memory cycles while >the rasterop hardware took over the data bus), but the microcode on that >machine was designed specificially to do that. The Z80 microcode isn't. If you then drive the bus, it will execute whatever you feed it, provided you do that during an instruction fetch cycle. >A front panel can certainly be made that takes over the entire bus and >generates address/data/control lines. > >> > >> >>What would you do with the HALT signal, and how would you implement it? >Remember on the Z80 (which is what I assume you're using based on the >signal names), Halt is an _output_ from the CPU to indicate that the CPU >has executed a halt instruction and is waiting for a reset/interrupt. > Of course! I'd forgotten that it raises that flag when it's halted. My steel-trap memory is gradually becoming a colander . . . <sigh> I don't believe I ever used that function on an S-100 . . . >-tony >

27 years, 3 months

1
0
0 0

More strange finds

by karlm＠blitzen.canberra.edu.au

Thanks for the info on the "Toaster", I'll fit a fuse into it and see if I can fire it up, it looks fairly clean so it should be ok. I might go back and see if the rest of the VSV11 is still around, there was a lot of DEC gear hanging around, mainly terminals. Another odd device I picked up this week is a "Sharp Portable Computer PC-2500", with a plotter-printer, it fires up, and gives me a menu of options for "Business Software", "Telephone Book" and "Basic", it has a 16k Ram card and what appears to be a serial port with an odd connector. I have searched high and low on the net for info on this but haven't been able to find much!! Cheers Karl ------------------------------------------------------------------------------ Karl Maftoum Computer Engineering student at the University of Canberra, Australia Email: k.maftoum(a)student.canberra.edu.au

27 years, 3 months

1
0
0 0

bringing up an 8f...

by allisonp＠world.std.com

<> Anyone with a schematic? This one is the rear mounted style with the <> cover that says, do not operate with cover removed for more than 15 <> minutes. Don't need the whole prints but only some things verified. <At the risk of sounding like a complete and utter moron, why can't you <operate for more than 15 minutes with the cover removed? Because the power supply would overheat and there is a thermal switch to shut it down. Allison

27 years, 3 months

1
0
0 0

id this Xerox

by g＠kurico.com

Ran across a Xerox today but couldn't find any identifying labels. It's a desk side sized (1' wide x 2' high x 3' deep), has a single 8" floppy above a control panel with a bottom hinged door. On the back, the connectors are on a separate little platform type thingy, on one side it has a printer, transceiver, and a db25 labeled LEUP. On the other side it had a db25 labeled display, a keyboard, and a "rigid disk" connector (and a plug that looks like it powers the drive). Anyone know what this beast is? TIA George

27 years, 3 months

4
4
0 0

Timonium Hamfest

by mbg＠world.std.com

>6 IBM PC Convertibles. Last summer I purchased about a dozen IBM PC >Convertible AC adapters at a hamfest for $1, knowing that some day I'd >come across a pile of Convertibles at a Hamfest, lacking power supplies. >Well wouldn't you know there was a stack of Convertibles at the Timonium >show - and not one of them had an AC adapter. If anybody's interested in >one of these, figure about $25. If any of them have a back-lit display, I'm interested. (Even if not, I'm interested, contact me off-list). 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, 3 months

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Help: root password for System V/i860

by ss＠allegro.com

Re: > >I just picked up an i860 box, which has System V on it ... and I don't > >know the root password. If I interrupt the boot cycle at the start, I'm still trying to figure this one out. "boot" and "boot -s" and "boot -fubar" all get me to: mboot enter name of the kernel to boot: (i.e., "boot" doesn't appear to have any parameters, or else it's doing a darn bad job of parsing the input ... computers should *always* complain about unused/extra input from a human on a command line :) So, in the "boot" dialog, if I hit <return>, it boots to "unix" (and requires a regular login, which I can't do) If I enter "unix -s", or "unix s" or "-s unix" or "unix -ss" or "fubar" , it says: Boot: Cannot load XXX: file not opened where "XXX" is whatever text I entered (e.g., "unix -ss" or "fubar") If I can't get past this, I'll try mounting the hard drive on a Unix machine somewhere, to see if I can find/edit /etc/passwd. Stan

27 years, 3 months

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PDP-11/34A rebuild project Was: Re: Post-move diary

by mbg＠world.std.com

>That sounds like the cache+FPU connector, and it's used like you said. >There's a second connector with a different number of pins (I forget the >details) that you _also_ need. It links the FPU to one of the CPU boards. >So in the end there are 2 top connectors on the FPU and one of them also >goes to the cache. Then I've found them both... unfortunately the boards don't work. One has one of the red FS toe-tags on it. 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, 3 months

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