test-drb May 2005

test-drb@ccmp.vtda.org

248 participants
723 discussions

by ajp166＠bellatlantic.net

> >Subject: Re: What does PUSHJ do? > From: Johnny Billquist <bqt at Update.UU.SE> > Date: Thu, 12 May 2005 10:30:31 +0200 (CEST) > To: cctalk at classiccmp.org > >Not a good example. It should really be JMS FOO, and at the label FOO you >need to place a 0, which is overwritten by the return address. (What >assembler do you usually use, btw? Comments come after a slash... :-) ) Mindeye. Neumonics to octal on paper usually. My 8 doesn't have any mass store not even TTY. I plan to take some EEprom and make a RS08 or other disk equivelent. >Eh? No. The PDP-8/a don't have any stack IOT. Same set as the 8/e. The >only difference is how some illegal combinations of OPR instructions act. I've used one that did. Might have been a hack. The 6120 however does and the DEC purchase spec is clear on that too. It's still done with IOTs. Allison

19 years, 2 months

What does PUSHJ do?

by bqt＠Update.UU.SE

On Wed, 11 May 2005 Allison <ajp166 at bellatlantic.net> wrote: > >Subject: What does PUSHJ do? (was Re: was "C on the PDP-8 ... ") > > From: spc at conman.org (Sean 'Captain Napalm' Conner) > > Date: Wed, 11 May 2005 17:43:49 -0400 (EDT) > > To: cctalk at classiccmp.org > > > >It was thus said that the Great Brad Parker once stated: > >> > >> heh. I remember puzzling at the the "pushj"'s and "popj"'s in the FOCAL > >> source code. This was before I had seen a pdp-11 or dec-10. > > > > What does PUSHJ actually do? I remember reading about it in Steven Levy's > >Hackers, but never got what was so special about it. > > > > It's a PAL macro for push and jump and there is a return and pop. Not to mention the fact that on the PDP-10 there actually was the instructions PUSHJ and POPJ, which probably was the inspiration for the macros on a PDP-8. The PDP-10 is a fun architecture. You can do subroutine calls in all the paradigms available. Stack? Sure. Return address at the start of the routine? Sure. Return address in a register? No problem. > Come from the fact that PDP-8 put the return address at the called location and the next > location is executed. > > MAIN ; do something > JMS I,FOO > ; more something > > > FOO ; return stored here > Add I,BLAH > JMP I,FOO > > In PDP-8 the I in the addressing is use the contents at the address > pointed to. Not a good example. It should really be JMS FOO, and at the label FOO you need to place a 0, which is overwritten by the return address. (What assembler do you usually use, btw? Comments come after a slash... :-) ) > Now if you want recursion > > You call a standard call and return routine (COSMAC 1802 requires this too). > > The routine gets the target address(work routine) and the return adddress > (caller) and saves the return and dispatches to the work routine. The > reverse is done to get back to the originating caller. Yup. > In the PDP-8A and 6120 there are IOTs to push/pop the ACC on the stack > and and also there are a set of push/pops for the PC register. Eh? No. The PDP-8/a don't have any stack IOT. Same set as the 8/e. The only difference is how some illegal combinations of OPR instructions act. The CPU deals with almost no IOTs itself. You then have the KK8A and DKC-8AA which handles most IOTs of the machine which are considered to be built in. > However the PDP-8 programmer is less likely to use a stack than a > flavor of computed jump or call. PDP-8 is good candidate for an > state machine coding. Of course, since there isn't any stack in hardware. Johnny Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at update.uu.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

19 years, 2 months

3B2/MIPS/PPC/Cray Garage Sale Update

by dlinder＠uiuc.edu

The 3B2s, Motorola PPC 801, and Cray Amber terminal have been claimed. Still available: >A MIPS Magnum 4000PC.50 >(2) SCSI1 External DAT drives. >misc AT era PC cases/motherboards >borken laser printer >Epson LQ1100 dot matrix printer Once again, I don't have details, but can pass along questions, comments, or snyde remarks. Pickup in Champaign/Urbana, IL is preferred, or I can meet you at the Dayton Hamvention next week (!). The owner will also consider shipping if it's something you're interested in and you can pay a bit to cover packing, shipping, etc. Thanks, Dan

19 years, 2 months

Anyone near Glasgow

by williams.dan＠gmail.com

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=96944&item=5192249… Looks like there could be some good stuff here. Dan

19 years, 2 months

Infocom on PDP-11

by dwight.elvey＠amd.com

>From: "Vintage Computer Festival" <vcf at siconic.com> > >On Wed, 11 May 2005, John Foust wrote: > >> At 10:12 AM 5/11/2005, Vintage Computer Festival wrote: >> >I miss GOTO. It was unnecessarily expunged from the programmmer's toolbox >> >by elitist academics. >> >> It's a tool. Why, I discussed this with a "Sam Ismail" back in 1999: > >This just goes to show how brainwashed I've become with regards to the use >of GOTO's ;) > >I'm going to stick a GOTO into some code at an inappropriate place today >just to spite the Man! > Hi It just doesn't fit nicely with things like memory allocation, scoping and pointers. It still has a place in error and exception handling. I guess one is suppose to handle such things in assembly. This is not a high level function? How can one make a system robust and not consider the need for such things? Dwight

19 years, 2 months

TI-980B

by aek＠spies.com

> I've been half-heartedly looking for a programmers console. The 990 programmers panel is a serial peripheral to the CPU Quite different from the one on the 980.

19 years, 2 months

TI-980B

by Tim＠rikers.org

In looking through some salvage equipment I came across a TI-980B (1974ish) in unknown condition. I don't have a use for it. Does someone else? It's in Dallas, TX. I don't yet know how much I'd have to pay for it, but I'll need to decide by tomorrow. Please contact me off list if interested. Feel free to reply to the list if you have other useful info on the system. http://rikers.org/gallery/hardware-20050511 Related Links: http://www.bitsavers.org/pdf/ti/980/ http://www.cozx.com/~dpitts/ti990.html -- Tim Riker - http://Rikers.org/ - TimR at Debian.org Embedded Linux Technologist - http://eLinux.org/ BZFlag maintainer - http://BZFlag.org/ - for fun!

19 years, 2 months

Dec stuff

by KParker＠workcover.com

Can anyone help please - I'm looking for a keyboard and mouse for a DEC Station 5000/125 to complete my machine - I'm located in Australia but will gladly pay packing and shipping costs. ++++++++++ Kevin Parker Web Services Consultant WorkCover Corporation p: 08 8233 2548 m: 0418 806 166 e: kparker at workcover.com w: www.workcover.com ++++++++++ ************************************************************************ This e-mail is intended for the use of the addressee only. It may contain information that is protected by legislated confidentiality and/or is legally privileged. If you are not the intended recipient you are prohibited from disseminating, distributing or copying this e-mail. Any opinion expressed in this e-mail may not necessarily be that of the WorkCover Corporation of South Australia. Although precautions have been taken, the sender cannot warrant that this e-mail or any files transmitted with it are free of viruses or any other defect. If you have received this e-mail in error, please notify the sender immediately by return e-mail and destroy the original e-mail and any copies. ************************************************************************

19 years, 2 months

Floppy Sleeves

by birs23＠zeelandnet.nl

Seems I had some extra time on my hands for another useless thingie, this time its a collection of Floppy Sleeves. I know there is already one out there but it hasn't been maintained in ages so I thought I start it again. Check it out at http://www.oldcomputercollection.com/floppysleeves/ Cheers, Stefan. ------------------------------------------------------- http://www.oldcomputercollection.com

19 years, 2 months

What does PUSHJ do? (was Re: was "C on the PDP-8 ... ")

by ajp166＠bellatlantic.net

> >Subject: What does PUSHJ do? (was Re: was "C on the PDP-8 ... ") > From: spc at conman.org (Sean 'Captain Napalm' Conner) > Date: Wed, 11 May 2005 17:43:49 -0400 (EDT) > To: cctalk at classiccmp.org > >It was thus said that the Great Brad Parker once stated: >> >> heh. I remember puzzling at the the "pushj"'s and "popj"'s in the FOCAL >> source code. This was before I had seen a pdp-11 or dec-10. > > What does PUSHJ actually do? I remember reading about it in Steven Levy's >Hackers, but never got what was so special about it. > It's a PAL macro for push and jump and there is a return and pop. Come from the fact that PDP-8 put the return address at the called location and the next location is executed. MAIN ; do something JMS I,FOO ; more something FOO ; return stored here Add I,BLAH JMP I,FOO In PDP-8 the I in the addressing is use the contents at the address pointed to. Now if you want recursion You call a standard call and return routine (COSMAC 1802 requires this too). The routine gets the target address(work routine) and the return adddress (caller) and saves the return and dispatches to the work routine. The reverse is done to get back to the originating caller. In the PDP-8A and 6120 there are IOTs to push/pop the ACC on the stack and and also there are a set of push/pops for the PC register. The general PDP-8 archetecture is very unique in that IOTs are really a handoff of the CPU core and registers to the device. So it's possible for IO hardware to get the PC save it and add a number to it and put it in the PC. The EMA is IO hardware. Oh, and they can also ouput/input from the ACC too. However the PDP-8 programmer is less likely to use a stack than a flavor of computed jump or call. PDP-8 is good candidate for an state machine coding. Allison

19 years, 2 months

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test-drb May 2005