test-drb November 2004

test-drb@ccmp.vtda.org

207 participants
458 discussions

one more question about pdp8/e console switches behaviour

by pete＠dunnington.u-net.com

On Nov 11 2004, 13:29, Gooijen H wrote: > Hmm, is that behaviour of a real pdp8/e console logical? > I am not saying it is wrong; perhaps the impementation DIGITAL > made is a little strange ...? I think it's perfectly logical. When you press EXAM, it increments the address ready to read the next word. When you press DEP, it increments the address ready for the next entry. Unlike a PDP-11, where sometimes it increments, sometimes not, and you have to remember the rules :-) It's just a different way of doing it. Remember this is a simpler machine, designed some years before the -11. > When you activate HALT (or SING STEP), the top row of lights > show the Memory Address (aka the Program Counter, PC). > When the knob is then set at "MD" the current instruction (at PC) > is displayed on the 'data' row of lights below the Memory Address. > So far so good (correct?). Yes, if you HALT a running program, that's correct. It displays the address just about to be used, logically, so that if you press CONT it starts at the address which is displayed, just as if you did an ADDR LOAD of that address, and then pressed CONT. > When you press EXAM the *first* time, the data still shows what > is at memory location [PC], but the Memory Address shows [PC+1] ... Yes. It shows the word at the address that was displayed just before you pressed EXAM. Having pressed EXAM, it then displays the next address. > That would mean that the displayed data and the displayed Memory > Address *can* be out of 'sync'. Only after you pressed EXAM at least > once you are sure that the displayed data is from location minus one > from the displayed Memory Address. > Is my understanding correct? It's not really out of sync. When running, or after a HALT, and BEFORE you tamper with any switches, the display shows the current address and the data at that address. Which is probably what you want, most of the time. If you then press EXAM, you will get the data from whatever address was current (and displayed) just before you press EXAM. If you press DEP instead, the data you write would go to the address that was current, and displayed, just before you pressed DEP. When you press either of those keys, the address is incremented ready for the next EXAM or DEP. > Other question. > Is the increment after EXAM (and DEP) *always* done on the pdp8/e? It's always done. It's done as you press the switch down. > The reason I'm asking is that on PDP-11's the repeated sequence > EXAM / DEP / EXAM / DEP, etc. does *not* increment the address. > Address increment is only done when EXAM is pressed after EXAM > was pressed. Likewise for a DEP / DEP sequence. PDP-8 users get the DEP right the first time, and don't need to check it ;-) -- Pete Peter Turnbull Network Manager University of York

20 years, 1 month

Needs Rescuing - Tektronics Terminal

by marvin＠rain.org

Oops, I should have mentioned that these are in Santa Barbara, California. His comment was that these are in pristine condition (although they are probably dusty from where they have been sitting.)

20 years, 1 month

Needs Rescuing - Tektronics Terminal

by marvin＠rain.org

A friend of mine has two Tektronics T-4109 terminals w/ keyboards and graphics tablet that need to go away today or tomorrow. Does anyone want these? I can pick them up and hold for a short while if necessary.

20 years, 1 month

Shipping a Model 33 (RO) Teletype

by brian＠quarterbyte.com

Definitely do not let them ship it in a box filled with peanuts. With a heavy object, some sort of liquefaction occurs and the object bangs around inside the box. Poured foam can work if the thing is sealed in a plastic bag. I've had very good luck when the shipper has used pieces of rigid styrofoam, even scraps broken up from the large styrofoam castings used to ship monitors or computers, fit tightly on all six sides of the object being shipped, leaving no empty volume. I just received a paper tape punch and reader from the Netherlands shipped this way and there wasn't a crack or scratch. Brian =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _| _| _| Brian Knittel _| _| _| Quarterbyte Systems, Inc. _| _| _| Tel: 1-510-559-7930 _| _| _| Fax: 1-510-525-6889 _| _| _| Email: brian(a)quarterbyte.com _| _| _| http://www.quarterbyte.com

20 years, 1 month

I need 5251 keyboard photo

by jwstephens＠msm.umr.edu

I need a photo of a 5251 keyboard with enough detail to make out the keyboard layout if possible. email if you can scan or photograph one for me from some place. thanks, jim

20 years, 1 month

Subject: Toshiba T4400 password

by Watzman＠neo.rr.com

Yes, it's not too difficult to remove passwords from older Toshiba models. There are 2 ways, basically. One uses a dongle on the parallel port, the other uses a floppy diskette with some magic bytes in a particular place on the disk. Both the dongle and pre-made floppies are sold on E-Bay. With a bit of effort, you can track down information on how to make either yourself.

20 years, 1 month

one more question about pdp8/e console switches behaviour

by djg＠drs-c4i.com

I think people have answered your questions but if not my online PDP-8 interface should work like the real front panel. It is a real 8/E but the web interface is a custom board I made. I copied the front panel logic so it should act the same and it seemed to in my testing. http://www.pdp8.net/run.shtml David Gesswein http://www.pdp8.net/ -- Run an old computer with blinkenlights. Have any PDP-8 stuff you're willing to part with?

20 years, 1 month

one more question about pdp8/e console switches behaviour

by GOOI＠oce.nl

Hmm, is that behaviour of a real pdp8/e console logical? I am not saying it is wrong; perhaps the impementation DIGITAL made is a little strange ...? When you activate HALT (or SING STEP), the top row of lights show the Memory Address (aka the Program Counter, PC). When the knob is then set at "MD" the current instruction (at PC) is displayed on the 'data' row of lights below the Memory Address. So far so good (correct?). When you press EXAM the *first* time, the data still shows what is at memory location [PC], but the Memory Address shows [PC+1] ... That would mean that the displayed data and the displayed Memory Address *can* be out of 'sync'. Only after you pressed EXAM at least once you are sure that the displayed data is from location minus one >from the displayed Memory Address. Is my understanding correct? Other question. Is the increment after EXAM (and DEP) *always* done on the pdp8/e? The reason I'm asking is that on PDP-11's the repeated sequence EXAM / DEP / EXAM / DEP, etc. does *not* increment the address. Address increment is only done when EXAM is pressed after EXAM was pressed. Likewise for a DEP / DEP sequence. again, TIA, - Henk, PA8PDP. > The position is always relevant, but you don't set it to AC. You set > it to MD (Memory Data). And when you press EXAM (or DEP), the address > displayed on the upper row will increment (but the data displayed will > remain the same, the data for the address that was current when you > pressed EXAM/DEP).

20 years, 1 month

I finally got something on topic outside Token Ring! hehe...

by john_boffemmyer_iv＠boff-net.dhs.org

A fellow IBM'er of mine is selling me his complete IBM PS/2 system. It's MicroChannel AND has Token Ring! woohoo. It is also SCSI! I am also getting a MAU in original plastic still WITH reset tool. yippie. I can add that to the 24 port Bay Networks (now Nortel) Baystack 504 (mod) that I have. Now all I need to do is toss in a few larger SCSI drives and find someone nice enough to have a copy of the MCA configuration floppy that I will be needing. Once I know the specific unit, I will ask the list for help on that. More than likely, I know I'll get a few flames, but hey, gotta ask as it will be my main machine/server on the TR side of the network. It is currently running DOS and a semi-modified Windows 3.1 (?). I want to do something, like toss Debian on it as it has a very nice net install and works well for me so far. Any suggestions guys? -John Boffemmyer IV ---------------------------------------- Founder, Network Engineer, Tech Analyst and Web Designer Boff-Net Technologies http://boff-net.dhs.org/index.html ----------------------------------------

20 years, 1 month

one more question about pdp8/e console switches behaviour

by GOOI＠oce.nl

Thanks very much for the clear answer, Pete. I have a webpage "in development", and hope to add a few pictures representing the latest state of affairs. There is also a ZIP file but it is an old version ... I will clean up the current source (remove some debugging stuff) and make that available for download as well. If you have a working Core Board *with* the extra 16k RAM chip, you can run the pdp8/e simulation without the I/O Board by just assembling the source with the "RealCons" conditional set to 0. The wiring details (and more) are all in the source file. The link to the page is: www.pdp-11.nl -- the click on [Homebrew 'PDP-11'] in the menu at the left, and on the page that opens click the link [spin off] at the top right. enjoy (?), - Henk, PA8PDP. > -----Original Message----- > From: cctalk-bounces(a)classiccmp.org > [mailto:cctalk-bounces@classiccmp.org]On Behalf Of Pete Turnbull > Sent: donderdag 11 november 2004 9:08 > To: General Discussion: On-Topic and Off-Topic Posts > Subject: Re: one more question about pdp8/e console switches behaviour > > > On Nov 11 2004, 8:32, Gooijen H wrote: > > Hello all, > > > > I have the pdp8/e *including* the console running on the Core > > 6809 Board (plus one I/O Board)! > > Nice! I look forward to seeing this. > > > If the HALT (or SING STEP) switch is down, you can use the EXAM > > and DEP momentary switches. If I press EXAM, I want to see the > > 12-bit word contents of the address currently on display in the > > top row (memory address) of the console. > > That 12-bit word is displayed on the 12 lights below the memory > > address lights. Is it correct that the position of the selector > > switch (the rotary knob) must be on "AC" to see the contents of > > the active address? Or is its position not relevant while HALT > > (or SING STEP) is active which seems odd to me because you want > > to be able to see more than just the AC when you HALTed the CPU? > > The position is always relevant, but you don't set it to AC. You set > it to MD (Memory Data). And when you press EXAM (or DEP), the address > displayed on the upper row will increment (but the data displayed will > remain the same, the data for the address that was current when you > pressed EXAM/DEP). > > > The answer seems easy, I just want to hear confirmation. > > The current implementation shows the contents briefly after I > > pressed EXAM *and* the knob is on "AC". Just *very briefly*, > > then the simulation shows the actual AC content again. > > It shouldn't do that. > > > So, on a real pdp8/e I assume that when the knob is on "AC" you > > see the contents of AC when HALT is active? > > Yes, without any glitches from the data. But only if the rotary knob > is turned to the AC position, otherwise you see whatever you've > selected (STATE, STATUS, AC, MD, MQ, BUS). > > > In that case, after the user pushed EXAM once (and the memory > > contents is displayed as I described above), how does he get to > > see contents of the "AC" again? > > > > Hope I made myself clear why I asked the question ... > > > > TIA, > > - Henk, PA8PDP. > > -- > Pete Peter Turnbull > Network Manager > University of York

20 years, 1 month

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test-drb November 2004