test-drb

test-drb@ccmp.vtda.org

101090 discussions

by tonym＠compusource.net

But, I wonder if we've seen the last of that clone? Tony -----Original Message----- From: tiggerlasv at aim.com Sent 6/17/2008 10:06:36 PM To: cctalk at classiccmp.org Subject: Apple I back up on ebay . . . . and, it has sold, for about $2000 . . . Thud (That was me passing out, from disbelief.) T

17 years, 10 months

Emailing CP-M Z80 home brew computer circuit board.htm

by lynchaj＠yahoo.com

Emailing CP-M Z80 home brew computer circuit board.htm Eric Smith eric at brouhaha.com <mailto:cctalk%40classiccmp.org?Subject=Emailing%20CP-M%20Z80%20home%20brew% 20computer%20circuit%20board.htm&In-Reply-To=2A5D64469F2B4C2AAF06BA09719DFB0 1%40andrewdesktop> Tue Jun 17 18:19:21 CDT 2008 * Previous message: Emailing CP-M Z80 home brew computer circuit board.htm * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ Andrew wrote: > Still how do you transfer stuff from a floppy ( or file online ) to a > CP/M system with no external I/O devices? I have yet to see a CP/M system with no external I/O devices. That doesn't sound very useful, so why would one care about transferring stuff to it? Eric -----REPLY----- Hi, Who said the N8VEM SBC has no external devices? The SBC has some self contained memory drives but supports external devices over the ECB. The SBC supports a RAM drive (448K B:) and two ROM drives (32K A: and 992K F:) internally. The CBIOS *currently* (read the CBIOS source) supports IDE interface and three hard disk partitions (8M C:, 8M D:, 1M E:) via the Disk IO board. I know the 8M C: drive is fully functional since I have one on my workbench. You can transfer temporary files in and out of the system using the serial line into the RAM drive or burn them into EPROM. The data is available on each device exactly the same except ROM drives are RO and the RAM drive is RW. CP/M CBIOS treats them as block devices and from an operators view they are identical to disk drives. Were there floppy disk with the same DPB as the ROM, the ROM image would also work as a disk image. I do not see why someone who wanted to couldn't write a serial based block device in CP/M and treat the host PC as a block device disk drive. It is of no real interest to me but the modifications to the CBIOS would not be all that hard. You'd also have to write an application on the PC side to handle the serial IO block servicing and with the terminal emulation. It'd be tedious but probably not too difficult. For me XMODEM works just fine to transfer any files to/from the PC as needed. I also do a lot of work off target on the PC and transfer the final binary image to the SBC for testing. The SIMH simulator supports an N8VEM mode I use a lot for development and test (Thanks Howard!) The IDE interface requires the Disk IO board which I have on my bench as a prototype built with prototype cards. The schematics/CBIOS source are available if you'd like to build one too. It also includes a NEC 765 based floppy controller interface. The IDE interface works for sure as I used it for quite a while. The floppy interface is built but never fully tested. My prototype board based system started having problems with reliable grounding when I took a break to work some other projects. The next project is to make an ECB backplane and then a bus debugger from my existing prototypes. After that, recraft the Disk IO board as manufactured PCB. The first thing I did when I restarted the project is begin the conversion of prototype boards to manufactured PCBs. Compared to my original prototype computer, the new manufactured PCB SBC is MUCH more reliable and easier to build. If there are enough units out there to make it worthwhile, I may order several manufactured PCBs for other hobbyists. If not, I will probably just go with another small run of barebone prototype boards for the rest of my boards. I did a run of two SBC prototype PCBs to verify the design before I did this latest run of manufactured PCBs. As for CP/M, you are not REQUIRED to use it. Write your own stuff and burn your own EPROM. However, a plain Z80 SBC is perfectly useful without CP/M. CP/M is just an operating system. CP/M works fine loading and running programs from the RAM/ROM drives however you could just as easily just use the RAM monitor. Better yet, write your own kernel and application. Whatever you like. I split my usage about 50% between the monitor and CP/M. Home brew computers are *not* all nicely finished and debugged so it magically does everything want when you plug it into a wall. That is what makes them a challenging and an enjoyable hobby. People who take it on should expect to get their hands dirty. If you are expecting a pristine flawless commercial product then this project is not for you. Thanks and have a nice day! Andrew Lynch

17 years, 10 months

Apple I back up on ebay

by tonym＠compusource.net

I think the "Vintage computer expert" stuff got his last one canned... If you notice, the ORIGINAL $10K listing had *NONE* of our "questions" posted. All of a sudden, in the second listing, there were "experts" popping up all over the place. Me, I'm no Apple 1 expert, by even the FURTHEST stretch of the imagination... Even *MY* untrained-on-Apple-1 eyes could see it was a fake. I'm hoping this dude ends up sharing a cell with a 6'5" 270lb guy named Bubba.... Tony -----Original Message----- From: Mike Loewen mloewen at cpumagic.scol.pa.us Sent 6/17/2008 7:22:55 PM To: General Discussion: On-Topic and Off-Topic Posts cctalk at classiccmp.org Subject: Re: Apple I back up on ebay On Tue, 17 Jun 2008, Grant Stockly wrote: Can you guys still get to the auction page? All I get is "This listing (220246863432) has been removed or is no longer available. Please make sure you entered the right item number. " Try this one: 220247416953 Mike Loewenmloewen at cpumagic.scol.pa.us Old Technologyhttp://sturgeon.css.psu.edu/~mloewen/Oldtech/

17 years, 10 months

Emailing CP-M Z80 home brew computer circuit board.htm

by lynchaj＠yahoo.com

Emailing: CP-M Z80 home brew computer circuit board.htm bfranchuk at jetnet.ab.ca bfranchuk at jetnet.ab.ca <mailto:cctalk%40classiccmp.org?Subject=Emailing%3A%20CP-M%20Z80%20home%20br ew%20computer%20circuit%20board.htm&In-Reply-To=4855CBD5.9050403%40bellatlan tic.net> Tue Jun 17 11:09:33 CDT 2008 * Previous message: Emailing: CP-M Z80 home brew computer circuit board.htm * Next message: Emailing CP-M Z80 home brew computer circuit board * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ Allison wrote: > > Have you ever used 8"SSSD to do anything that required space? There > isn't > enough space to run a disassembled version of the BDOS through ASM > unless you have at least two drives and don't mind doing cleanup. > I never could run the CP/M system I was using for more than 30 minutes with out the floppy stepper sticking. That was fun working with it. Still how do you transfer stuff from a floppy ( or file online ) to a CP/M system with no external I/O devices? > Yes you can roll your own data sep it only needs three ttl packages. > With all the other hardware needed for the 765 case you end up with at > least 10 chips > though If you willing to miss a few features it's been done in 7 plus > the FDC > and that doesn't include the bus side of the FDC interface. > That I would like to see. > > Kicad for linux there are other like cadstd for winders. > Of course the last 2901 design I'd done in the early 80s was > with paper and pen! It's doable that way. I still am using paper & pen. Mind you I have to buy JAPANESE pens since the quality of the USA stuff is all cheap Chinese imports. Now that I have a serious cad program - DIPTRACE on order I think I will put the design in hardware. > FYI using 250nS eproms will make it terminally slow unless > you do two things, use a wide microword 64bits or more and > pipeline the address and decode so you can work right to the > eprom Tacc minimum limit. I got that covered if I read the 2901 data sheets correctly. I will be using a 6809 style memory cycle optimized for D-RAM access and clock the 2901 in 4th phase of the memory cycle. This is retro computing project for the feel of the late 1970's not using a 8 bit CPU. I am aming for a 800ns memory cycle and the slow access of micro-code is not a problem. The only thing pipelined is the next memory cycle - Read/Write/Refesh and the default is refresh while doing the the 1st cycle of op-code decoding. The front panel does RUN/STOP, Single Instruction,Address Load, Deposit,Read. -----REPLY----- Hi, I can answer the question on how to get programs and data into and out of the SBC. There are three ways with the basic SBC; 1) XMODEM at the CP/M prompt 2) Intel Hex format transfer at the RAM Monitor prompt and 3) burn your own EPROM with the supplied image or your own custom disk image (utilities are on the website) Here is a little background on the N8VEM SBC design principles The N8VEM SBC is meant to be flexible and low cost. If you start with the PCB only, you can minimize cost by not installing unneeded functions such as; 1) RTC 2) 8255 PPI and parallel port connector 3) ECB Bus transceivers and DIN 41612 connector You can also substitute some parts to reduce cost. Replace the 1Mx8 EPROM with a 128Kx8 27C1001 is a drop in replacement. Scrap and salvaged parts can be used directly or with minor modifications. All the chips are commonly available plain TTL and can be substituted. All of the other components can be substituted if you know what you are doing. Scrap 29C020 Flash ROM chips (PC BIOS) can be reused with a simple shim socket. Most likely 128Kx8 SRAM parts with a shim socket can be used but I haven't tested it yet Installing and running CP/M 2.2 OS is strictly a convenience and an option. Any generic CP/M application should work. The RAM and ROM drives are lightning quick and silent. You'll never see a hung stepper motor with SRAM! The SBC boots into the RAM monitor so you may never need to run CP/M at all if you don't want to. The system I built is rock solid. It runs for hours doing things without a sound or glitch. I used some CMOS components so the SBC runs cool. Power supplies are easy and cheap. Use spare ATX/AT PS or your own with the common Molex drive connector. Of course, all the hardware and software details are fully published and with datasheets for all the components. Except for the EPROM there are no custom or programmed devices at all. All components are bog standard common 74LSxxx TTL and LSI peripherals. It is designed to be built with low cost tools and simple test equipment such as 25W soldering iron and VOM. EPROM programmer, logic probe and/or oscilloscope are useful but optional. You can easily write your own replacement software like a FORTH kernel or custom Z80 boot code if you'd like. The EPROM on the N8VEM site is strictly optional and I actually discourage people from using the pre-programmed part. Write/burn your own and save $$$ on construction. With the low cost PCB available and using standard low cost components anyone can build their own SBC for low cost. You can add the features you like later on and even expand the system via the ECB to be a full blown microcomputer. Once a few of these systems get built "out in the field" I would like to start a challenge to see who can build an SBC for the least cost. Those with a well stocked junk box or access to scrap PC electronics would have an advantage of course. Compared to a design it yourself using wire wrap/prototype boards/breadboards, this SBC PCB will save you time and money on construction. Manufactured PCBs are also more reliable than temporary construction methods in the long term. It will be fun to make, useful, and educational. Thanks and have a nice day! Andrew Lynch

17 years, 10 months

Apple I back up on ebay

by tonym＠compusource.net

Now it looks like his buddies are doing the "ask seller a question" One says: "Hello Sir, I am an expert in vintage computers, and you sir have the real deal, this is not a fake. The style of the board will show, and the use of vintage chips. Good luck" Wow - some expert. Actually, from the wording, sounds like that person wants to send a certified check for 3 times the amount, and then send the balance to his shipper in ....... Wish we knew who THAT was, so we know who else to avoid! There's also: "This looks like its the true Apple 1, how can you say its not?" What a scammer... Tony -----Original Message----- From: dwight elvey dkelvey at hotmail.com Sent 6/17/2008 1:27:21 AM To: General Discussion: On-Topic and Off-Topic Posts cctalk at classiccmp.org Subject: RE: Apple I back up on ebay Hi One might check out: http://www.newtontalk.net/archive/newtontalk.2006-02/0072.html Dwight _________________________________________________________________ Instantly invite friends from Facebook and other social networks to join you on Windows Live" Messenger. https://www.invite2messenger.net/im/?source=TXT_EML_WLH_InviteFriends

17 years, 10 months

Emailing: CP-M Z80 home brew computer circuit board.htm

by ajp166＠bellatlantic.net

> >Subject: Re: Emailing: CP-M Z80 home brew computer circuit board.htm > From: "bfranchuk at jetnet.ab.ca" <bfranchuk at jetnet.ab.ca> > Date: Tue, 17 Jun 2008 10:09:33 -0600 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >Allison wrote: >> >> Have you ever used 8"SSSD to do anything that required space? There >> isn't >> enough space to run a disassembled version of the BDOS through ASM >> unless you have at least two drives and don't mind doing cleanup. >> >I never could run the CP/M system I was using for more than 30 minutes >with out >the floppy stepper sticking. That was fun working with it. BTDT.. :( >Still how do you transfer stuff from a floppy ( or file online ) to a >CP/M system with no external I/O devices? Explain no external IO? A serial line works fine, or a parallel bidirectional port. Since every cp/m system has a console no rule saus it can transfer files on that line either. >> Yes you can roll your own data sep it only needs three ttl packages. >> With all the other hardware needed for the 765 case you end up with at >> least 10 chips >> though If you willing to miss a few features it's been done in 7 plus >> the FDC >> and that doesn't include the bus side of the FDC interface. >> >That I would like to see. Goo look at David Dunfield's CUBIX system. CPU is 6809 but the FDC is 765 with minimal interface parts count. I'd say it was a good example of keep ing the chip count to a minimum. >> >> Kicad for linux there are other like cadstd for winders. >> Of course the last 2901 design I'd done in the early 80s was >> with paper and pen! It's doable that way. >I still am using paper & pen. Mind you I have to buy JAPANESE pens >since the quality of the USA stuff is all cheap Chinese imports. >Now that I have a serious cad program - DIPTRACE on order >I think I will put the design in hardware. I still use paper and pen too. I do everything engineering notebook style. That is black ink, no erasures and numbered pages. >> FYI using 250nS eproms will make it terminally slow unless >> you do two things, use a wide microword 64bits or more and >> pipeline the address and decode so you can work right to the >> eprom Tacc minimum limit. >I got that covered if I read the 2901 data sheets correctly. >I will be using a 6809 style memory cycle optimized for >D-RAM access and clock the 2901 in 4th phase of >the memory cycle. This is retro computing project for the feel >of the late 1970's not using a 8 bit CPU. I am aming for >a 800ns memory cycle and the slow access of micro-code >is not a problem. The only thing pipelined is the next memory >cycle - Read/Write/Refesh and the default is refresh while >doing the the 1st cycle of op-code decoding. The front >panel does RUN/STOP, Single Instruction,Address Load, >Deposit,Read. Using Dram is one way to make life hard. you can use larger static devices and save pain but retain the same cycle style. Last 2901 design was 16bit, horizontal microcode (56bits), one microword to a cycle. I was able to get the pipeline for Eprom address latch to overlap so that the 2732s used would run at 320ns with good timing. The macro cpu executed instructions in that time cycle in a four tick cycle. It was fairly fast for a single address machine. However, I didn't do the microaddress or micro program counter in the 2901 I did that with TTL. No front pannel either the system booted a rom minimal debugger. When I got it working I junked it and started thinking about a 32bit machine. Allison

17 years, 10 months

CP-M Z80 home brew computer circuit board

by ajp166＠bellatlantic.net

> >Subject: Re: CP-M Z80 home brew computer circuit board > From: "Eric Smith" <eric at brouhaha.com> > Date: Mon, 16 Jun 2008 13:58:30 -0700 (PDT) > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Chuck wrote: >> the 1770/72/73 have just about everything in a neat little 28-pin package. >[...] >> DMA not required. > >Whether DMA is required or not has nothing to do with which member of >the 177x/179x/279x/MB88xx family you use. It's determined by whether >you can write tight enough transfer loops to avoid write underruns and >read overruns. > >On a 6502 a typical read transfer loop takes a minimum of 22 cycles, >so a 1 MHz 6502 can keep up with 5.25 inch single and double density and >8 inch single density with programmed I/O. 8 inch double-density >requires a faster processor, DMA, or special tricks. > >With a Z80 a typical read transfer loop takes a minimum of 52 clocks, >which on a 2 MHz Z80 meets the requirements for all but 8" double density, >which requires a faster processor, DMA, or special tricks. > >On either processor, unrolling the loop does not shave off enough cycles >to get to the 8" double density transfer rate. > >Note that the read loop has to be capable of reading bytes at about >20% faster than the nominal rate or overruns become likely. > > nominal nominal required read loop > format xfer rate byte time byte time > ---------- ---------- --------- ------------------- > 5.25" FM 125 Kbps 64 us 52 us > 5.25" MFM 250 Kbps 32 us 26 us > 8" FM 250 Kpbs 32 us 26 us > 8" MFM 500 Kbps 16 us 13 us > >> The 765-based all-in-ones such as the National 8473 and the WD37C65A >> are about as hard to obtain and are a little more difficult to >> interface to a Z80 (just about require DMA and interrupts to work >> right). > >The 765-based controllers work fine with or without DMA. Again, the >issue is the data rate. > >Eric You hit the nail on the head. Interfacing 765 or 179x or any of the other flavors is about the same from the bus side be it 8080/8085/z80 or 6502. As long as you can poll within the minimum read/write loop time it's fairly easy. If not in the 8080/8085/z80 world you can use processor ready line to do a stall-wait on DRQ to keep the loop in sync and save some 22 T-states. I forget if 6502 has a ready wait line. >From a simple SBC perspective even the 1770 series requires some glue and will inflate the parts count a fair amount. The more common 1793 or 765 will require enough parts to double or triple the parts count. All of the 37C65 (and 37C665) parts work ok (witness the P112) but go scarce as the PC industry drives their existance and disappearance. Easy yes, simple, only if your not doing the work. However add a floppy and who's supporting all them when someone wants to interface some oddball pertec or CDC or Amdek 3" that "doesnt work with the SBC floppy"? I've built my fill of floppy based, IDE based, CF based, ROMdisk based systems and the latter two are far easier to construct and get going and if your trying to run CP/M and mess with programming and applications the smaller lower power SBC can be its own form of fun as you can put it in a small box with a wall wart and use the laptop as a terminal anywhere. Having a few PX-8s, Darth Vaders lubch boxes and S100 systems with all the disks and what not is fine but when you want to move them it's not so fun using hand truck. Where my tiny Z80 with 32MB CF in a 5x4x1.5" box is rather fun to bring and show CP/M and what it can still do, on batteries! Allison

17 years, 10 months

SBC6120 (Dec PDP 8 on a chip) on ebay

by rborsuk＠colourfull.com

Hi All, Never got around to assembling my Spare Time Gizmos SBC6120. Just put it on ebay if anyones interested. Item #300234398483 Rob Rob Borsuk email: rborsuk at colourfull.com Colourfull Creations Web: http://www.colourfull.com

17 years, 10 months

CP-M Z80 home brew computer circuit board

by ajp166＠bellatlantic.net

> >Subject: Re: CP-M Z80 home brew computer circuit board > From: "Roy J. Tellason" <rtellason at verizon.net> > Date: Sun, 15 Jun 2008 17:22:48 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >On Sunday 15 June 2008 16:43, Chuck Guzis wrote: >> From: "Andrew Lynch" >> >> > Implementing floppy IO can take on many variations and picking the FDC >> > is just the first of many challenges [FDC1793? NEC765? SMC9266? >> > WD2797?]. What about the data separator? Few chips remain and viable >> > sources are scarce. Even integrated FDCs with built in data separators >> > are not readily available. >> >> The WD1770/1772/1773 is still my favorite "almost no external >> circuitry" chip, but they're getting harder to find, in spite of >> being used on Atari and Commodore boxes. You don't need to buffer >> the floppy interface and the things have integrated data separators-- >> and come in a 28-pin package. > >I thought it was the 179x parts that had the data separator on-chip, no? No. 1770 did as did 2793... Allison > >-- >Member of the toughest, meanest, deadliest, most unrelenting -- and >ablest -- form of life in this section of space, ?a critter that can >be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" >- >Information is more dangerous than cannon to a society ruled by lies. --James >M Dakin

17 years, 10 months

IDT tape drive information

by aek＠bitsavers.org

This should be a Pertec formatted 800/1600bpi drive. I have a slightly earlier version. I'm pretty sure I have a manual for it, will dig around.. Curiously, I wasn't able to get it to work correctly with a Pertec to SCSI converter out of a Qualstar transport.

17 years, 10 months

Emailing: CP-M Z80 home brew computer circuit board.htm

by lynchaj＠yahoo.com

CP-M Z80 home brew computer circuit board bfranchuk at jetnet.ab.ca bfranchuk at jetnet.ab.ca <mailto:cctalk%40classiccmp.org?Subject=CP-M%20Z80%20home%20brew%20computer% 20circuit%20board&In-Reply-To=5E5B27B6AB204FE39BB21B75D4C8713B%40andrewdeskt op> Sun Jun 15 12:06:33 CDT 2008 * Previous message: CP-M Z80 home brew computer circuit board * Next message: big bucks for a Tek computer on eBay * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ Andrew Lynch wrote: > -----REPLY----- > > Hi! Thanks Jim for the comments. Please let me address the issues raised > by Ben: > > If you look closely at the SBC design, you'll notice it has a feature even > better than a floppy controller -- it has a fully buffered IO bus! It > contains all the Z80 signals brought out to the DIN 41612 connector. The > peripheral bus adheres to the published ECB standard. > > If you want floppy IO, the solution is simple -- just design one and attach > it to the bus! I have already done this with my Disk IO board (IDE and > NEC765 FDC) which plugs into my home brew ECB backplane along with the SBC. > Assuming there is enough interest in these home brew SBCs, I hope to make a > PCB version of the Disk IO board. > Well when you get a PCB of the Disk I/O board , I'll take the set of PCB's. Will a 8272 (intel) Disk controler replace the NEC765? for the floppy controler for the track formatting for CP/M? Unicorn Electronics is my favorite shopping for electronic parts and I can find a 8272 there. -----REPLY----- Hi Ben, Of course, the NEC 765 and Intel 8272 are virtually the same part and are as common as dirt. I believe Intel licensed the NEC 765A and just renamed it the i8272 or something like that. However, getting the FDC chip is the trivially easy part. Getting a data separator is a much more difficult problem. Have you tried finding an FDC9229 recently? How about a SMC FDC9216 or UMC 8326? Even the FDC1793 requires a DS chip. I challenge you to even *FIND* a FDC9229 *datasheet* these days. DS chips are nearly unobtainium or at least very difficult to get. I have a few and but not many. They are hard to find. For a DS you can probably substitute a ROM based state machine or even hack it out using SSI TTL chips. However, then you'll have a much larger PCB that'll cost a small fortune to manufacture and few can afford. If you try to use an integrated FDC with DS built in, you'll run into even more problems. Chips like the WD2797 and SMC9266 have built in data separators but are even more scarce and expensive than the data separator chips. In short, if just adding Floppy IO to a SBC were an easy task, you see more home brew SBCs available with them. I am trying to build an SBC that any hobbyist can afford, build reliably, and have a reasonable chance of success. That means compromises had to be made and some stuff had to go. Anyone can design a great computer on paper. Making a real, tangible part is a lot more difficult. Using cool sounding but almost impossible to find parts seems easy but it makes the SBC practically worthless. If you can make a low cost Z80 SBC that includes floppy IO, I would love to see it. I'd even buy one or two. I look forward to seeing your design. Thanks and have a nice day! Andrew Lynch

17 years, 10 months

IDT tape drive information

by ian_primus＠yahoo.com

I'm looking at buying an IDT (Innovative Data Technology) tape drive, model TD-1054/INTL. I don't have any information on it other than that. It's a manual thread drive, and appears to be 800/1600bpi. But, what I can't tell from the seller's pictures is the interface. He thinks it's Pertec, but doesn't know. I don't have a formatter board, all my machines are set up to communicate with formatted Pertec drives. It _appears_ to have two 50 pin connectors on the board, but it looks like a couple of the fingers aren't populated. I don't remember ever seeing a Pertec drive like that. (but I could be wrong...) I've emailed the seller asking for a better picture, but I was hoping that someone here might have some knowledge about this drive. Thanks! -Ian

17 years, 10 months

Zork for CP/M setup question

by ethan.dicks＠usap.gov

Hi, All, With all the CP/M questions flying around (and some by me), I ran across an interesting archive at one of the CP/M respositories - Infocom games *plus* setup files for random CP/M environments. The source provided starts like this: ;Copyright 1982 Infocom, Inc. All rights reserved. ;Configuration Program for INTERLOGIC(tm) CP/M Files ;Configured for basic no-frills terminal ;This program should be edited to specify terminal and ;printer parameters for your CP/M system. Edit this ;file, then assemble, load, and run the program. ;Complete documentation of the setup procedure will ;be found in your INTERLOGIC Reference Card. ;Terminal and printer specific parameters start at ;the label CPMCPL, about 20 lines below. Nothing ;prior to that label should be altered. ... and what follows are a set of data storage spots to fill in with who-knows-what to customize interpreter behavior for your environment. Does anyone have a copy of the aforementioned "INTERLOGIC Reference Card" for CP/M versions of the games? I'm running things under the altair/altairz80 emulators that are part of SIMH. I have CP/M, etc., working fine - I just need the text from the Infocom reference card that would have come in the game box. Thanks, -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 17-Jun-2008 at 10:00 Z South Pole Station PSC 468 Box 400 Temp -64.8 F (-53.8 C) Windchill -92.1 F (-69.0 C) APO AP 96598 Wind 6.5 kts Grid 351 Barometer 673.2 mb (10886 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html

17 years, 10 months

Fixing a DEC Letterwriter (LA100)

by aek＠bitsavers.org

I just put a few documents up under http://bitsavers.org/pdf/dec/terminal/la100 that might be helpful.

17 years, 10 months

CP-M Z80 home brew computer circuit board

by cclist＠sydex.com

> From: "Eric Smith" <eric at brouhaha.com> > Whether DMA is required or not has nothing to do with which member of > the 177x/179x/279x/MB88xx family you use. It's determined by whether > you can write tight enough transfer loops to avoid write underruns and > read overruns. More or less what I was trying to say (however clumsily). > On either processor, unrolling the loop does not shave off enough cycles > to get to the 8" double density transfer rate. For more conversation on transfer loop speeds, see my comments on Herb Johnson's Retrotechnology site. By getting clever with code, you can turn in some pretty fast transfer loops even on a lowly 2 MHz 8080. For example, if we assume that the controller will assert wait states if an input is attempted on the data port until a byte becomes available and interrupts on operation complete, a 2MHz 8080 transfer loop could handle an 8" MFM transfer like this: LXI H,floppy$byte floppy$byte: clocks 2mhz IN fdcport ;FDC port 10 5 uS PUSH PSW ;store 2 bytes 11 5.5 uS PCHL ;loop 5 2.5 uS Total: 26 13 uS Now, of course, you've got to unravel what you've got on the stack to get your data back, but you've gotten it--at 2MHz and on an 8080 yet. Caveat: I haven't tried this, except on paper. If you were to unroll the loop to a series of IN/PUSH pairs, the byte time should drop to 10.5 usec, more than fast enough for an 8" MFM transfer. But that discussion's from the days when silicon was expensive. An inexpensive async FIFO would get rid of the problem entirely and allow for transfer at one's convenience. The point that I was trying to make was that the 1770/2/3 make for very easy interfacing with a minimum of parts--and are very easy to program. They feature a small package and were designed for 5.25"/3.5" drives. Were I prototyping a small PCB with a Z80 and floppy support, they'd be my first choice. Cheers, Chuck

17 years, 10 months

History of AMP?

by evan＠snarc.net

Per the subject line ... does anyone know of a good history of AMP? Either online or in book form ...

17 years, 10 months

non-CP/M Z80 board

by dm561＠torfree.net

--------ORIGINAL MESSAGE: Date: Mon, 16 Jun 2008 22:04:49 -0400 From: "Roy J. Tellason" <rtellason at verizon.net> Subject: Re: non-CP/M Z80 board <snip> I'm not familiar with many 6800 designs, but I was somewhat surprised to see how limited some parts are, like the 8085 in the "8085 Cookbook" where you could really get away with very little. OTOH, the c64 doesn't use any buffering _at all_ and yet the CPU in there seems to have little trouble driving 3 ROM chips, a set of 8 4164s, plus all the peripherals. I'm guessing that the Z80 is probably somewhere in between, and that the datasheet probalby won't give me the whole story anyhow. <snip> --------REPLY: Don't forget that CPUs like the 8085 need data/address MUX chips anyway, which are usually also buffers. m

17 years, 10 months

Fixing a DEC Letterwriter (LA100)

by dm561＠torfree.net

---------ORIGINAL MESSAGE: Date: Mon, 16 Jun 2008 22:23:39 +0200 From: "Steve Maddison" <steve at cosam.org> Subject: Re: Fixing a DEC Letterwriter (LA100) 2008/6/16 M H Stein <dm561 at torfree.net>: > Various patterns of DSR and POWER/FAULT flashing are the diagnostic > failure codes; what pattern do you have that is not documented? > > Defective RAM is 8 flashes BTW. Yep, I figured that one out the long way. I only have some user docs so this wasn't listed, just things like "out of paper" and "cover open". I'm now back to the original CTS and ONLINE combination (no flashing). --------REPLY: POWER/FAULT not flashing should indicate that it has passed POST; DSR means what you'd think, that DSR is active. Looks like it thinks everything's OK. 1 to 9 flashes indicate faults with ROMS 1 to 7 & normal/extended RAM. Steady flash, no bell: open cover or paper fault. Steady flash w/bell: head jam or servo motor/encoder m

17 years, 10 months

non-CP-M Z80 board

by lynchaj＠yahoo.com

non-CP/M Z80 board Roy J. Tellason rtellason at verizon.net <mailto:cctalk%40classiccmp.org?Subject=non-CP/M%20Z80%20board&In-Reply-To=> Mon Jun 16 20:01:54 CDT 2008 * Previous message: Fixing a DEC Letterwriter (LA100) * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ I'm thinking about building a z80 board, with varying amounts of "stuff" attached, with RAM and ROM that may be NMOS or CMOS, and some indeterminate number of Z80-family and compatible peripheral chips. My question is this: At what point do you _need_ to have address and data bus buffer chips? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin -----REPLY----- Hi, I think the safe range for 74LSxxx style TTL is about 5-10 or so connections per output gate. You can compute the ratio of the various datasheet currents and get a more exact figure. However, here is a pretty good set of "rules of thumb" for circuit design: http://kurser.iha.dk/eit/dtm1/DTM1_html/Wakerly/udgave3/xc03.pdf See line 3.49 for the table of the various combinations. They say 74LSxxx on 74LSxxx can do up to 20 but I'd keep it lower to be safe. That should be enough for some static RAM, a ROM, a couple of peripherals, some simple glue logic and that's about it. You can stretch it a bit using CMOS chips or the more recent TTL families as long as you keep the PCB fairly compact. Doing anything more than the above or going off board with a bus requires buffers. You'll find there are few if any absolute rules on the subject but lots and lots of opinions. If you examine the IBM XT motherboard schematic, you'll see it uses many buffer chips -- primarily due to the DRAM, ISA bus interface, and decent sized PCB. On the WaveMate Bullet schematic, it has many buffers to for similar reasons. There is only so big you can make the PCB and only so much current can be sunk before the signals start to degrade. If you want to avoid buffers, think 1) small PCB, 2) small number of chips, and 3) shortest wiring connections as possible. Thanks and good luck with your project! Andrew Lynch

17 years, 10 months

time to part with my PDP-11 system

by dm561＠torfree.net

Date: Mon, 16 Jun 2008 03:54:51 +0000 From: Ethan Dicks <ethan.dicks at usap.gov> Subject: Re: time to part with my PDP-11 system <snip> >...Eventually, I'll do another camping trip to Hamilton... <snip> -ethan --- I'm in Hamilton every week or so, and I have to ask: why? ;-) mike

17 years, 10 months

Fixing a DEC Letterwriter (LA100)

by dm561＠torfree.net

-----------ORIGINAL MESSAGE: Date: Mon, 16 Jun 2008 11:06:36 +0200 From: "Steve Maddison" <steve at cosam.org> Subject: Re: Fixing a DEC Letterwriter (LA100) 2008/6/14 Tony Duell <ard at p850ug1.demon.co.uk>: >> Anyway - the original problem is gone. With the (half) new RAM I'm now >> getting what at least appears to be a proper fault indication on the >> LEDs: both DSR and POWER/FAULT are flashing. This combination isn't in >> the user manual so my guess is it's failing the POST. If any of the > > Maybe soemthing like 'RAM Error' :-) That was my first guess too. Running the ROM through a simulator and forcing the RAM test to fail confirms it. The problem? I'd managed to gouge out a bit of track while removing the ICs - just so happens it was one of the very tracks connecting /all/ the RAM to the address bus, so checking for continuity between the sockets I'd soldered in didn't reveal the problem. So I fixed that and robbed a couple more 2114s from another machine. So all RAM is replaced but, lo and behold, ONLINE and CSR are back with a vengeance. So I'm basically back to square one, although not entirely as it would at least appear the RAM is OK. It could of course still be failing in one of the peculiar ways you mentioned and still pass the POST... Otherwise it would appear the original LED combination was directly asserted by the processor, so it should be traceable in the ROM code. -- Steve Maddison http://www.cosam.org/ "The great thing about standards is that there are so many to choose from." ---------REPLY: Various patterns of DSR and POWER/FAULT flashing are the diagnostic failure codes; what pattern do you have that is not documented? Defective RAM is 8 flashes BTW. You ran the ROM through a simulator??? There's an LA100 simulator? m

17 years, 10 months

Anyone in or near Acton MA that could do me a favor?

by ian_primus＠yahoo.com

Is there anyone in or close to Acton MA that could pick up some computer terminals for me? Unfortunately, they need to be picked up during business hours M-F, and while I'm willing to make the drive to Acton to pick them up, I can't get there during the week because of work. There's only seven of them, so they'd fit in a car. But, shipping would be prohibitive. So, basically, I want to see if someone would be willing to pick them up and hold them for me until this (or next) weekend, where I could make the drive. Thanks! -Ian

17 years, 10 months

Fixing a DEC Letterwriter (LA100)

by dm561＠torfree.net

---------Original Message: From: "Steve Maddison" <steve at cosam.org> Subject: Fixing a DEC Letterwriter (LA100) Hello all, I have a half-dead Letterwriter 100 KSR here I'd like to get working again. I get a short buzz from the paper feed motor at power-up but instead of flashing all it's indicator LEDs, both CTS and LINE stay illuminated. There's no carriage movement and the keyboard does nothing either. The basic vital signs are OK but I'm stuck without a service manual or schematics. Does anyone have access to these docs? I'd of course also be interested to hear of any common problems and/or things to check before I dive into all-out mending mode... Cheers, -- Steve Maddison http://www.cosam.org/ ----------Reply: Can't suggest where to start checking but I do have several RO LA100s awaiting the trip to the scrapper, in case I can help with any non-kbd parts before they go. I do also have the tech manual somewhere; unfortunately IIRC it's on 17" paper so I can't scan it. I believe Tony also has a copy and more knowledge/experience than I; maybe he has some suggestions. m

17 years, 10 months

time to part with my PDP-11 system

by dgahling＠hotmail.com

I have a PDP-11 system, fairly recent, about the size of a mini-fridge, on wheels. last I checked it was still fully operational, but I can't speak to that now, it's spent the last 2 years in storage. I just don't have space for it, and it's a bit larger than I can find use for. its about 4 feet long, 2 feet wide and perhaps 3 feet high - thats by eye ball. it has a TK70 tape drive that's in excellent shape. the plastic cover over the front is missing which is why I'm not sure of the model. I'd rather sell or trade it, if there's interest. i'm looking for a vax station 3100 model 76 or a 4000 model 90 or some volker craig terminals. I'd prefer to avoid junking it. Keep in mind I'm not interested in shipping it, it weighs a bloody ton! located in Scarborough, Ontario (Canada), so anyone in the GTA area would be an easier pick up. Dan. _________________________________________________________________ If you like crossword puzzles, then you'll love Flexicon, a game which combines four overlapping crossword puzzles into one! http://g.msn.ca/ca55/208

17 years, 10 months

Apple I on ebay

by marvin＠west.net

If this is the Apple I I'm thinking of, it WAS bought at a garage sale for a couple of bucks. The person selling it said they were going to put it on oBay, and a friend of his and mine asked me about it. I referred them both to Sellam, and this is the first I've heard about it since then. > From: Al Kossow <aek at bitsavers.org> > Subject: Re: Apple I on ebay > > "This computer will only be sold to a MUSEUM OR SERIOUS COLLECTOR ONLY" > > > eBay is absolutely the WRONG venue to try proving that. > > The whole notion of someone going to an estate sale and picking this > up is unfortunate as well. I though Sellam knew where all of them were?

17 years, 10 months

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb