test-drb January 2008

test-drb@ccmp.vtda.org

221 participants
430 discussions

by dm561＠torfree.net

Date: Mon, 28 Jan 2008 15:11:42 -0800 (PST) From: Fred Cisin <cisin at xenosoft.com> Subject: Re: Z80 Divide by 10 >>> Can we just shoot the designers of the 8086 and just leave it that. !? On Mon, 28 Jan 2008, Jim Leonard wrote: >> But seriously -- why? I didn't find it all that horrible -- in fact, I >> missed the string handling (REP MOVSW/STOSW/SCASW/etc.) on all the other >> platforms I mentioned. If they truly deserve to be shot, I want to know >> why :-) >Some people get rather upset at the lack of symmetry, and lack of certain >instructions that might be handy, such as a load immediate into segment >registers. ---- And some people just get rather upset by _anything_ that doesn't match their view of how the world "should" be... m

16 years, 3 months

non-existence of printer collectors...proven wrong

by Arno_1983＠gmx.de

Sat, 26 Jan 2008, "Chuck Guzis" <cclist at sydex.com> wrote: > Okay, so who wants a working Diablo Hitype II? Spare wheels and >(probably dried-out) ribbons. Free for pickup, or for the cost of > shipping. Probably in America and thus out of my reach, unless somebody coming to the upcoming VCFe in Munich offered to bring it along. "Ed" <listmailgoeshere at gmail.com> wrote: > Back in 1995 I used an IBM 3262 belt printer which was attached to an > AS/400. I don't know what its native interface was, but the company I > was working for had got hold of a third-party interface box that was > mounted on the side of said printer and connected it to the AS/400 via > twinax. Funny thing was, there was also a Centronics socket on the > base of said interface unit... > That unit would do 600LPM, so I was told. It was about a 1m x 1m x 1m > cube, and it was *loud*. Ah, I totally forgot about telling that I at one time also was involved with the rescue of such a setup (3262 and interface box) from a big mailorder store in Germany, which was passed to Hans Franke for possible future use with his/our 4331. The print server or how it's to be called boots from a floppy disk on power-up. The printer had been transported to my school in the Janitor's van and stored there for some weeks. When we came to pick it up in with our station wagon, it showed that the unfortunate piece of equipment was a tiny bit too large to fit through the hatch although there would have been ample space inside. We solved the problem by rolling the printer to our garage on it's own casters (one block from the school) and taking off the outer panels there so we could deliver it to Munich the following weekend. In my list, I forgot to mention my only GPIB-enabled printer, a CBM 8023 (9 needles, IIRC). At the risk of leaving the classic definition of "printers", I also have to brag about last week's great find, an Agfa PCR II film recorder, unfortunately missing the camera body that belongs to it - a modified Nikon N6000, according to internet sources. So long, Arno -- Arno Kletzander Student Assistant // Studentische Hilfskraft Informatik Sammlung Erlangen www.iser.uni-erlangen.de GMX FreeMail: 1 GB Postfach, 5 E-Mail-Adressen, 10 Free SMS. Alle Infos und kostenlose Anmeldung: http://www.gmx.net/de/go/freemail

16 years, 3 months

8-bit micro MMU's

by cclist＠sydex.com

> From: Alexis > Subject: 8-bit micro MMU's > Maybe someone can use this? I haven't looked deeply into the MP/M II > XIOS requirements so I may have left something out that it needs so is > anyone familiar with the XIOS? (Raises hand) For MP/M and CP/M Plus, this is probably far too elaborate. It's my experience that MP/M appears to be designed around the idea of a 16K bank size. So, for 256K, you need only to be able to select 16 banks of 16K. A fairly common 74LS670 should do the trick. A 74LS610 or 612 should be more than adequate for most large-scale MP/M applications, but I understand that they're getting hard to come by. They can sometimes be found on early 286 motherboards as the DMA bank select register. (PC XTs and ATs have to perform bank-selection for DMA, as they use an 8237 DMA controller model, which is limited to 64K addressability). I made the mistake of (just before the '610 came out) designing a bank-select circuit for an 8085 product. It used a Fairchild 64x9 bipolar RAM (power-hungry and expensive) to give granularity of 1K pages. With MP/M, this was overkill. 16K would have done just fine and saved time and money. With the slow memory chips back then, making things work with the wretched 8202 DRAM controller was a real chore. I seem to recall that if you ran worst-case numbers, you could wind up with the requirement of a negative access time for the DRAM for a 5MHz 8085. Adding bank-mapping hardware in the address path didn't improve things any. The comment about separating data and address space is worth considering, but be aware that, because of deficiencies in the instruction set and for performance and space needs, 8080 self- modifying code is not uncommon. For example, consider the problem of I/O to a variable port number. SHLD-ing into the operand field of an LXI instruction to save a few cycles and bytes is also common in my experience. For what it's worth. Cheers, Chuck

16 years, 3 months

The Centronics connector

by cclist＠sydex.com

> Date: Sun, 27 Jan 2008 19:32:35 -0800 > From: Brent Hilpert <hilpert at cs.ubc.ca> > > I thought it was "Amphenol 57 Series". > > I suspect "Blue-Ribbon" may be the name of the original larger style, and > "Micro-Ribbon" is the name of the smaller style more popular now-a-days. > > If that's correct, the plug-in input modules for 60's-era tube Tekky > scopes (for example) used a Blue-Ribbon connector, while the Centronics > connector is a Micro-Ribbon connector. Going fom the Amphenol web-site, 57 > series appears to be either a synonym for the Micro-Ribbon series or a > subset of the Micro-Ribbon series. I've heard the telco variety also called "Champ" connectors. You used to see a lot of them used to connect desk sets (e.g. 2565) to a PBX or 1A2 KSUs. Also known as an RJ21 connector. The 36-pin Centronics as well as the 24-pin GPIB variety are both members of the Amphenol "Micro ribbon" family. The same 50-position connector type was used quite a bit for connecting SCSI-I devices. Cheers, Chuck

16 years, 3 months

6800 C compilier

by grant＠stockly.com

Is there a 6800 C compilier for CPM or DOS? I've been looking but can't seem to find one. If anyone knows where I could get one that would help me out a ton... Grant

16 years, 3 months

Dead IBM PC 5150 motherboard - help troubleshooting

by richard.beaudry＠gmail.com

Hello all and thanks for the suggestions... Here's the story so far: 1) Power appears good -- measured correct voltages at power supply header on motherboard, and at various chips on the motherboard. All seem to be within specs 2) "Power good" line stays at +5VDC -- I believe this is correct, and signals that power is indeed good 3) Processor reset line -- at power up, briefly goes to +5VDC, then back to 0VDC and stays at 0VDC -- I don't think it is active low, so this should be correct, right?? 4) Triple-checked configuration switches, and they are correct for the configuration 5) Clock input to 8088 is dead-on 4.77xxxxxx MHz (my scope shows all the digits, but I don't remember them :-) -- I think the 4.77MHz is close enough). 6) One thing that seems odd is that the ADxx (Address/Data) lines seem "stuck". The scope does not show a waveform, and measuring with a meter shows some lines right at +5VDC, some at about +4VDC and some at 0VDC. Perhaps the processor is indeed HALTed??? That's where I am right now ... I'll remeasure the ADxx lines, and post the full list of values .... Thanks again for all the suggestions!!! Rich B.

16 years, 3 months

The Centronics connector

by dm561＠torfree.net

----------Original Message: From: Fred Cisin <cisin at xenosoft.com> Subject: RE: The Centronics connector On Mon, 28 Jan 2008, dwight elvey wrote: > Hi > Things seem to have drifted a little. It is the wire combination > that I'm interested in. I'm aware that the connector was there > before the printer. > It looks like to the best of knowledge, the 101 may have been > the first. What type of printer was that? ISTR that there was also a 100 ? The 101 was BIG. It was HEAVY. Substantially bigger and heavier than Laserjet -. It was fast. It was LOUD! But, it would fit into the back of a Civic hatchback. I had one sitting around for years. I took it to some of the John Craig Computer Swaps in San Jose, and siome of the "Northwest" ones in San Mateo. I could not sell it. Not for $100; not for $50; not for $20 I gave it to City College Of San Francisco in 1983? when I was doing some part-time teaching there. They stated a value of $1200! so I got a LOT more off of my taxes than I could have gotten from a sale. IF they have stopped using it by now, then it was NOT because it was worn out. -- Grumpy Ol' Fred cisin at xenosoft.com ***********Reply: I used a 101 for years; great machine, similar in size & weight to the line printers I was using at Burroughs, even used a form control tape. Also as noisy; it was in a back room of the basement, connected to the CBM 8032 in my upstairs office with a 50 foot ribbon cable. Length restrictions on parallel cables? Feh! Still have the cable and many of the printouts... mike

16 years, 3 months

8" floppy connector READY signal

by ccmpcpg＠yahoo.de

Hi, I've built the 8" <--> PC adapter described on Dave Dunfield's site. It works well with an 8" drive from an Olivetti M40 system. But it doesn't work with a Shugart SA851 drive. Now, after checking the pin description in the SA851 OEM manual it seems that the SA851 uses pin #22 instead of pin #12 for READY. I haven't tried yet whether the adapter works if I change it for pin #22... I'm just asking if it's a well known fact that there appear to be different layouts of the 50pin 8" floppy connector. I was under the impression that it is quite standard. I'll probably add a switch to the adapzer to select between pin #12 and pin #22. regards, chris __________________________________ Ihr erstes Baby? Holen Sie sich Tipps von anderen Eltern. www.yahoo.de/clever

16 years, 3 months

On collecting printers...

by tsw-cc＠johana.com

On a previous message, dwight elvey <dkelvey at hotmail.com> said: > Hi > Does anyone know which Centronix ( sp?) printer the 36 pin connector > for parallel printers became standard? > Dwight It seems that they started using it in the mid 70's. The connector was an Amphenol 36 pin "micro-ribbon" type, one of the various sizes available. As a point of reference IEEE-488 (HPIB) standardized on a 24 pin version of the connector, and the phone company (It was called the Bell System in those days) used a 50 pin version for their cabling of telephones (25 pair cables as well). The connectors were pretty common, and worked VERY well, as the wiping contacts were ultra reliable. In the lab where I was working at the time had standardized on the 50 pin version for connecting things together (this was in the mid 60's). So, the connector has been around for quite a while. Of course, I could comment on their choice of pinouts, being as how they switched the ground return from one side of the connector to the other about 1/2 way down (what were they thinking!). The problem is that this is now standard, and nobody wants to change it. (*SIGH*). In that era of computing (electronics) many connector styles were used. Some stayed on, and others died. The "D-sub" is another style (DA-15, DB-25, DC-37, DD-50 (three row!), and DE-9). People fail to understand that the "D" is the connector style, and the letter following (A-E) is the size of the connector. When IBM went to the DE-15 connector for VGA, they might have shown some people, but it still amazes me that the 9-pin connector (properly called a DE-9) is referred to by an incorrect name (not mentioned here!). -- Sorry, No signature at the moment. ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

16 years, 3 months

The Centronics connector

by aek＠bitsavers.org

>> Does anyone know which Centronix ( sp?) printer the 36 pin connector >> for parallel printers became standard? > I think it was the Centronics 770. It had severe problems though, > Centronics had to pull it from the market and thats when Epson jumped >into the market -- Try at least 10 years earlier. Models 101 and 306 used them (early 70's)

16 years, 3 months

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test-drb January 2008