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Opinion-Good "vintage" printer for an IMSAI?

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  • Richard Cini
    All -- Now that I have printing on my IMSAI working, I m shopping around for a dot matrix printer of a corresponding vintage-ness. In stock , I have an IBM
    Message 1 of 20 , Jun 1, 2013
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      All --

      Now that I have printing on my IMSAI working, I'm shopping around for a dot matrix printer of a corresponding vintage-ness. "In stock", I have an IBM ProPrinter (too new), a Tandy DMP-132 (also too new), and a Radio Shack DMP-120 (which kind of looks like the Centronics 739; a good possibility). 

      I was looking at an Okidata 182, but I wanted to see if there are any better options people could recommend or should I stick with the DMP-120.

      Also, somewhat related, what's the best way to reinvigorate printer ribbons? I've heard WD-40 but I have to believe that's kind of messy to do.

      Thanks again!

      Rich

      --
      Rich Cini
      Collector of Classic Computers
      Build Master and lead engineer, Altair32 Emulator

    • joshbensadon
      ... Wouldn t a Daisy Wheel printer be nice? WD-40 works great. I ve done it on the same ribbon a dozen times (over 12 years). Get the WD-40 that sprays like
      Message 2 of 20 , Jun 1, 2013
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        --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
        >
        > All --
        >
        > Now that I have printing on my IMSAI working, I'm shopping around for a dot
        > matrix printer of a corresponding vintage-ness. "In stock", I have an IBM
        > ProPrinter (too new), a Tandy DMP-132 (also too new), and a Radio Shack
        > DMP-120 (which kind of looks like the Centronics 739; a good possibility).
        >
        > I was looking at an Okidata 182, but I wanted to see if there are any better
        > options people could recommend or should I stick with the DMP-120.
        >
        > Also, somewhat related, what's the best way to reinvigorate printer ribbons?
        > I've heard WD-40 but I have to believe that's kind of messy to do.
        >
        > Thanks again!
        >
        > Rich


        Wouldn't a Daisy Wheel printer be nice?

        WD-40 works great. I've done it on the same ribbon a dozen times (over 12 years). Get the WD-40 that sprays like paint, unspool the ribbon with a pencil, give a very quick spray on the whole length of the ribbon, doesn't matter what side, wind it back up without touching.

        :)J
      • B. Degnan
        ... dot ... IBM ... possibility). ... better ... ribbons? ... Rich, Does it have to be a parallel printer? There are a lot of serial printers of the era that
        Message 3 of 20 , Jun 1, 2013
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          >
          > Now that I have printing on my IMSAI working, I'm shopping around for a
          dot
          > matrix printer of a corresponding vintage-ness. "In stock", I have an
          IBM
          > ProPrinter (too new), a Tandy DMP-132 (also too new), and a Radio Shack
          > DMP-120 (which kind of looks like the Centronics 739; a good
          possibility).
          >
          > I was looking at an Okidata 182, but I wanted to see if there are any
          better
          > options people could recommend or should I stick with the DMP-120.
          >
          > Also, somewhat related, what's the best way to reinvigorate printer
          ribbons?
          > I've heard WD-40 but I have to believe that's kind of messy to do.
          >

          Rich,

          Does it have to be a parallel printer? There are a lot of serial printers
          of the era that are easier to find, plus the terminal printer types like
          the Decwriter II and TI Omni 810's and such.


          Bill
        • Richard Cini
          Bill -- ... Actually, no it doesn t and serial is definitely more authentic. I m using parallel now because it s all I have. The LA36 was always my favorite
          Message 4 of 20 , Jun 2, 2013
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            Bill --

            >>Does it have to be a parallel printer? There are a lot of serial printers
            >>of the era that are easier to find, plus the terminal printer types like
            >>the Decwriter II and TI Omni 810's and such.

            Actually, no it doesn't and serial is definitely more authentic. I'm using parallel now because it's all I have. The LA36 was always my favorite — it's what we used in high school to connect to the local college mainframe. Some of the small-format dot matrix printers also came with a serial board option — I know that OKI has a board, as does Epson. Maybe I should pull out a BYTE magazine from 1977 or 1978 and see what's being advertised.

            Regarding Josh's comment about WD-40, are you referring to the non-areosol "Trigger Pro" version or just the regular aerosol?

            Rich

            --
            Rich Cini
            Collector of Classic Computers
            Build Master and lead engineer, Altair32 Emulator







          • joshbensadon
            ... I took a quick glance at a few early 1976 Popular Electronics, could not find any Printer Ad s. Then for the first time, I ve taken a glance at early 1976
            Message 5 of 20 , Jun 2, 2013
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              --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
              > ‹ I know that OKI has a board, as does Epson. Maybe I should pull out a BYTE
              > magazine from 1977 or 1978 and see what's being advertised.
              >
              > Regarding Josh's comment about WD-40, are you referring to the non-areosol
              > "Trigger Pro" version or just the regular aerosol?
              >
              > Rich

              I took a quick glance at a few early 1976 Popular Electronics, could not find any Printer Ad's. Then for the first time, I've taken a glance at early 1976 BYTE, and I could only find 1 printer. March 76, pg 80. General Electric TermiNet 30. Reminds me of the DecWritter in my old shop.
              On the previous page, I noticed a "Pot Position Digitizing Idea" using a 555 timer. I wonder if that's where the idea for the joystick input on the PC's came from?

              re: WD-40. I'm not familiar with the Trigger Pro. I use the regular aerosol, I guess. The best results are when you not douse any spot but give an even spray. Pretend you are spray painting, but put on a very thin coat. The ribbon will soak it in and distribute.

              :)J
            • Richard Cini
              ... , Richard Cini ... any Printer Ad s. Then for the first time, I ve taken a glance at early
              Message 6 of 20 , Jun 2, 2013
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                --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
                > ? I know that OKI has a board, as does Epson. Maybe I should pull out a BYTE
                > magazine from 1977 or 1978 and see what's being advertised.
                >
                > Regarding Josh's comment about WD-40, are you referring to the non-areosol
                > "Trigger Pro" version or just the regular aerosol?
                >
                > Rich

                >>I took a quick glance at a few early 1976 Popular Electronics, could not find any Printer Ad's. Then for the first time, I've taken a glance at early 1976 BYTE, and I could only find 1 printer. March 76, pg 80. General Electric TermiNet 30. Reminds me of the DecWritter in my old shop.

                I pulled out two issues — April 1978 and April 1979. There weren't many printer advertisements at all. But, where there were, in 1978 there were a couple 40-column models (MPI, Centronics Microprinter), the Teletype Model 43, an IBM Selectric conversion, an OKI 110, and a handful of Centronics 779, 700 and 703. Also listed were brand-specific printers for Commodore. 

                In 1979, in addition to the aforementioned, I saw the TI 810 ($1599), the Diablo 1641 daisy-wheel ($2900 – yikes!), and the DEC LA36. In 1979, the OKI was being sold as "surplus" for $650 (1978 "new" was $1279). The Centronics 779 was about $1100.

              • B. Degnan
                ... In the 70 s printing is what you sent via modem to your work or school system, over modem, to print remotely.... You might have luck using a TI Silent 700
                Message 7 of 20 , Jun 2, 2013
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                  > >>I took a quick glance at a few early 1976 Popular Electronics, could not find
                  > any Printer Ad's. Then for the first time, I've taken a glance at early 1976
                  > BYTE, and I could only find 1 printer. March 76, pg 80. General Electric
                  > TermiNet 30. Reminds me of the DecWritter in my old shop.
                  >
                  > I pulled out two issues - April 1978 and April 1979. There weren't many
                  > printer advertisements at all. But, where there were, in 1978 there were a
                  > couple 40-column models (MPI, Centronics Microprinter), the Teletype Model
                  > 43, an IBM Selectric conversion, an OKI 110, and a handful of Centronics
                  > 779, 700 and 703. Also listed were brand-specific printers for Commodore.
                  >
                  > In 1979, in addition to the aforementioned, I saw the TI 810 ($1599), the
                  > Diablo 1641 daisy-wheel ($2900 - yikes!), and the DEC LA36. In 1979, the OKI
                  > was being sold as "surplus" for $650 (1978 "new" was $1279). The Centronics
                  > 779 was about $1100.
                  >


                  In the 70's printing is what you sent via modem to your work or school system, over modem, to print remotely....

                  You might have luck using a TI Silent 700 as a printer, they were sold in various versions through the 70's including 1967-77 model. Save space that way.


                  BIll
                • joshbensadon
                  ... Last time I checked, I didn t have $650 of surplus money. :) I think a good reason to be a retro computer hobbyist is because things are so much cheaper
                  Message 8 of 20 , Jun 2, 2013
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                    > <mailto:midatlanticretro%40yahoogroups.com> , Richard Cini >
                    > I pulled out two issues ¡X April 1978 and April 1979. There weren't many
                    > printer advertisements at all. But, where there were, in 1978 there were a
                    > couple 40-column models (MPI, Centronics Microprinter), the Teletype Model
                    > 43, an IBM Selectric conversion, an OKI 110, and a handful of Centronics
                    > 779, 700 and 703. Also listed were brand-specific printers for Commodore.
                    >
                    > In 1979, in addition to the aforementioned, I saw the TI 810 ($1599), the
                    > Diablo 1641 daisy-wheel ($2900 ¡V yikes!), and the DEC LA36. In 1979, the OKI
                    > was being sold as "surplus" for $650 (1978 "new" was $1279). The Centronics
                    > 779 was about $1100.
                    >
                    > Rich

                    Last time I checked, I didn't have $650 of "surplus" money. :)

                    I think a good reason to be a retro computer hobbyist is because things are so much cheaper now!

                    You might want to look through some of the RE scans, I remember a few fat articles about computer reviews... there might be some printers in there too.

                    :)J
                  • s100doctor
                    Rich asks what seems to be a reasonable question - what vintage printer to obtain with a vintage IMSAI ? I won t post a (long) lecture about it, but the
                    Message 9 of 20 , Jun 2, 2013
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                      Rich asks what seems to be a reasonable question - what "vintage" printer to obtain with a "vintage IMSAI"? I won't post a (long) lecture about it, but the question is *actually NOT very reasonable*. It has a premise in it. The premise is that at the time of the IMSAI, one could buy "a printer" and it was "for the IMSAI", or for things like the IMSAI. Why not? IBM-PC's had IBM printers, Apple II's had Apple printers.....

                      "Why not?" is because all that, brand products and product lines, happened sometime after the IMSAI. There is no single "appropriate printer" in 1976 for a 1976 IMSAI - just whatever the hell you could come up with that printed. Teletype, old typewriter terminal, thermal printing terminals, some funky line printer from a minicomputer, and so on. And a handful of printer-mechanisms of various sorts, offered by some of the early micro-computer companies of the era. I think SWTPC sold a 40-column cash-register printer mech as a printer, at the time.

                      I'll avoid my standard lecture about "there were no standards" in the mid-1970's. Things were in process, stop expecting "standard" stuff, and leave it at that.

                      Rich and others eventually did the right thing - they went to the magazines of the era, and looked for what the hell was *available* at the time. That is, if you want a "1976 available printer" for your 1976 produced IMSAI.

                      The other premise, is that an IMSAI was used in 1976 - not later. But if you used the IMSAI in 1980, or 1985, for lack of some other computer; you probably got a printer from THAT era. (IMSAI's fell out of use in about a decade or so.) So they bought new or used 1980's printers for them. A 1990's laser printer on an IMSAI? Probably not often done.

                      That said, anyone could have done anything at any time. The nice thing about 1970's computing, is that you are not locked into some company's standards. Some people LIKE that, dudes. If Rich wants to do Postscript printing on his IMSAI and an Apple LaserWriter, he can ask Don Lancaster for tips. (Look it up.)

                      So which printer "should" Rich Cini use? Entirely depends on his goals for use, and for display to others, and his budget. An Epson or Okidata or Apple or other old dot-matrix printer is fine by me. I have all of them, used them all. They are a decade later but they are cheap enough then and now, and are "old", and portable. You can even buy new-stock typewriter ribbons for them (WD-40 my ASCII!) Daisy wheels, same deal but they may have daisy failures.

                      Pre-1975 manufactured printers are actually harder to find, hard to fix, take space and weight, and probably cost more now. Rich may not have that choice, not easily or cheaply. A model 28 TTY would be a cheap version of a model 33 TTY, for instance. Kinda noisy.....

                      If anyone complains about your printer as not "authentic", Rich, tell them that hobbyists in the era were pioneers and used what they could find to do what was needed. A 1976 BYTE or Kilobaud magazine will show them what was available. Don't forget to tell them what a thousand dollars could buy in 1976.

                      herb johnson
                      making do since the 1970's
                    • Dan Roganti
                      ... hey I think that was a song I remember from the 70s every time I wrote a Fortran program I kept hearing that song, it went something like this, *print that
                      Message 10 of 20 , Jun 2, 2013
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                        On Sun, Jun 2, 2013 at 4:24 PM, s100doctor <hjohnson@...> wrote:
                        , some funky line printer from a minicomputer

                        hey I think that was a song I remember from the 70s 
                        every time I wrote a Fortran program I kept hearing that song, it went something like this,
                        print that funky lineprinter, white boy, print that funky lineprinter right, print that funky lineprinter ,white boy, Lay down that wide-band greenbar and print that funky lineprinter till you die
                        haahaaa


                      • Richard Cini
                        ... obtain with a vintage IMSAI ? I won t post a (long) lecture about it, but the question is *actually NOT very reasonable*. It has a premise in it. The
                        Message 11 of 20 , Jun 2, 2013
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                          Herb, et. Al.:

                           

                          >>Rich asks what seems to be a reasonable question - what "vintage" printer to obtain with a "vintage IMSAI"? I won't post a (long) lecture >>about it, but the question is *actually NOT very reasonable*. It has a premise in it. The premise is that at the time of the IMSAI, one could >>buy "a printer" and it was "for the IMSAI", or for things like the IMSAI. Why not? IBM-PC's had IBM printers, Apple II's had Apple printers.....

                          >>There is no single "appropriate printer" in 1976 for a 1976 IMSAI - just whatever the hell you could come up with that printed. Teletype, old >>typewriter terminal, thermal printing terminals, some funky line printer from a minicomputer, and so on. 

                          Herb is right. I probably should have said "historically appropriate printer" in the original posting because I realize that at the time there wasn't an IMSAI-specific printer like that existed for the Commodore, Radio Shack or Apple. Bad shorthand on my part because that's not what I intended. But, Herb's second comment illuminated more of what I was looking for. 

                          My IMSAI was built somewhere in the period of March-June 1976. Let's say I saved up enough money from birthdays and holidays (I would have been 10 or 11 years old at the time; OK, so I had a generous grandmother) to buy a printer in 1977 or 1978 for the IMSAI. What would I have bought? If I had any BYTEs around, I would have come up with a few options.

                          Out of curiosity I pulled my Radio Shack catalogs. There was a store close-by that I hung out and played with the Trash 80 so I might have looked there. 1978 was the first meaningful computer catalog (RSC-2). It had a line printer in it that looks like a good candidate. No price. The 1979 catalog (RSC-3) had the same printer with a price - $1559. Ouch. A Centronics 779 was $1099 by mail order in 1978. Better call my grandmother again and say hello.

                          I also looked at War Games. Ok, so that's 1983, but I wanted to see what David had in his bedroom. Not a real close-up shot, but it looks like an Epson RX-80 or something similar on his desk to the left. Makes sense for 1983.

                          The DMP-120 I have was from 1985. Too late to be period-appropriate, but it works for now. I bought my Mac 512k in 1985 so the IMSAI would have been a door stop by then.

                           

                        • jack99rubin
                          Just for another reference point, I bought my IMSAI in 1982 from a Heath engineer and set it up with a Tarbell disk controller and the original IMSAI 8080,
                          Message 12 of 20 , Jun 2, 2013
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                            Just for another reference point, I bought my IMSAI in 1982 from a Heath engineer and set it up with a Tarbell disk controller and the original IMSAI 8080, though within a year or so, I replaced the CPU with a Z80 from Bill Godbout. I used it with a Soroc terminal and an Epson MX-80 printer. Ben Bronson, running the Hyde Park RCPM had the hot setup with an NEC Spinwriter. At some point later, I also had a surplus Diablo 630(?) daisy-wheel printer. All of these ran off a serial interface. I managed to find surplus Centronics 700 printers for work, which naturally enough, used a Centronics (parallel) interface to run off my Godbout systems which took USRobotics into the mid-80s and a bit beyond.

                            Jack

                            --- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:
                            >
                            > Rich asks what seems to be a reasonable question - what "vintage" printer to obtain with a "vintage IMSAI"? I won't post a (long) lecture about it, but the question is *actually NOT very reasonable*. It has a premise in it. The premise is that at the time of the IMSAI, one could buy "a printer" and it was "for the IMSAI", or for things like the IMSAI. Why not? IBM-PC's had IBM printers, Apple II's had Apple printers.....
                            >
                            > "Why not?" is because all that, brand products and product lines, happened sometime after the IMSAI. There is no single "appropriate printer" in 1976 for a 1976 IMSAI - just whatever the hell you could come up with that printed. Teletype, old typewriter terminal, thermal printing terminals, some funky line printer from a minicomputer, and so on. And a handful of printer-mechanisms of various sorts, offered by some of the early micro-computer companies of the era. I think SWTPC sold a 40-column cash-register printer mech as a printer, at the time.
                            >
                            > I'll avoid my standard lecture about "there were no standards" in the mid-1970's. Things were in process, stop expecting "standard" stuff, and leave it at that.
                            >
                            > Rich and others eventually did the right thing - they went to the magazines of the era, and looked for what the hell was *available* at the time. That is, if you want a "1976 available printer" for your 1976 produced IMSAI.
                            >
                            > The other premise, is that an IMSAI was used in 1976 - not later. But if you used the IMSAI in 1980, or 1985, for lack of some other computer; you probably got a printer from THAT era. (IMSAI's fell out of use in about a decade or so.) So they bought new or used 1980's printers for them. A 1990's laser printer on an IMSAI? Probably not often done.
                            >
                            > That said, anyone could have done anything at any time. The nice thing about 1970's computing, is that you are not locked into some company's standards. Some people LIKE that, dudes. If Rich wants to do Postscript printing on his IMSAI and an Apple LaserWriter, he can ask Don Lancaster for tips. (Look it up.)
                            >
                            > So which printer "should" Rich Cini use? Entirely depends on his goals for use, and for display to others, and his budget. An Epson or Okidata or Apple or other old dot-matrix printer is fine by me. I have all of them, used them all. They are a decade later but they are cheap enough then and now, and are "old", and portable. You can even buy new-stock typewriter ribbons for them (WD-40 my ASCII!) Daisy wheels, same deal but they may have daisy failures.
                            >
                            > Pre-1975 manufactured printers are actually harder to find, hard to fix, take space and weight, and probably cost more now. Rich may not have that choice, not easily or cheaply. A model 28 TTY would be a cheap version of a model 33 TTY, for instance. Kinda noisy.....
                            >
                            > If anyone complains about your printer as not "authentic", Rich, tell them that hobbyists in the era were pioneers and used what they could find to do what was needed. A 1976 BYTE or Kilobaud magazine will show them what was available. Don't forget to tell them what a thousand dollars could buy in 1976.
                            >
                            > herb johnson
                            > making do since the 1970's
                            >
                          • joshbensadon
                            ... I should have said, the WD-40 only works to moisten the ink *if* there s still ink on the ribbon. Over the past 12 years, I ve been doing this on the same
                            Message 13 of 20 , Jun 3, 2013
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                              --- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:
                              >You can even buy new-stock typewriter ribbons for them (WD-40 my ASCII!)

                              I should have said, the WD-40 only works to moisten the ink *if* there's still ink on the ribbon. Over the past 12 years, I've been doing this on the same ribbon for a printer that outputs 40 pages once a year (Prints schedules/results for a pinewood derby race). I suppose if that ribbon was continuously used for hundreds/thousands of pages, there just wouldn't be any ink left to moisten. Your mileage may vary.

                              :)J
                            • Rich Cini
                              This poses an interesting question -- someone must still sell ribbon ink, right? I remember sometimes using stamp pad ink but that dries too quickly. Rich Cini
                              Message 14 of 20 , Jun 3, 2013
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                                This poses an interesting question -- someone must still sell ribbon ink, right? I remember sometimes using stamp pad ink but that dries too quickly. 


                                Rich Cini
                                Sent from my iPhone


                                On Jun 3, 2013, at 7:48 AM, joshbensadon <no_reply@yahoogroups.com> wrote:

                                 

                                --- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:
                                >You can even buy new-stock typewriter ribbons for them (WD-40 my ASCII!)

                                I should have said, the WD-40 only works to moisten the ink *if* there's still ink on the ribbon. Over the past 12 years, I've been doing this on the same ribbon for a printer that outputs 40 pages once a year (Prints schedules/results for a pinewood derby race). I suppose if that ribbon was continuously used for hundreds/thousands of pages, there just wouldn't be any ink left to moisten. Your mileage may vary.

                                :)J

                              • joshbensadon
                                Hi, Does anyone have the RWTS for Apple DOS 3.2? I m specifically looking for the 5/3 bit encoding scheme they used.
                                Message 15 of 20 , Jun 3, 2013
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                                  Hi,

                                  Does anyone have the RWTS for Apple DOS 3.2? I'm specifically looking for the 5/3 bit encoding scheme they used.

                                  :)J
                                • Al Hartman
                                  At Zebra Systems, Inc., we used an IMSAI with a Z-80 card to run dBase II which ran our ordering/shipping system. It would output labels on standard mailing
                                  Message 16 of 20 , Jun 3, 2013
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                                    At Zebra Systems, Inc., we used an IMSAI with a Z-80 card to run dBase II
                                    which ran our ordering/shipping system. It would output labels on standard
                                    mailing labels for a reciept and the box to ship orders to customers. We
                                    used an Epson RX-80 F/T printer with a serial interface in the early 1980's.

                                    I would also output text blocks and headlines I'd paste up for our catalogs
                                    and ads using the same setup, Wordstar, and a program called Fancy Font. We
                                    later migrated the system to an MS-DOS compatible from Televideo using the
                                    same printer. I still used Wordstar and Fancy Font, just the MS-DOS rather
                                    than CP/M versions.

                                    They were both good, solid systems.

                                    I still have a pair of IBM Graphic Printers, which are re-branded Epson
                                    MX-80's. They need ribbons, I'm sure.

                                    Al
                                  • Andrew Molloy
                                    Not positive, but I think Beneath Apple DOS covers it. http://archive.org/details/Beneath_Apple_DOS Andy
                                    Message 17 of 20 , Jun 3, 2013
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                                      Not positive, but I think Beneath Apple DOS covers it.


                                      Andy


                                      On Mon, Jun 3, 2013 at 10:36 AM, joshbensadon <no_reply@yahoogroups.com> wrote:
                                       

                                      Hi,

                                      Does anyone have the RWTS for Apple DOS 3.2? I'm specifically looking for the 5/3 bit encoding scheme they used.

                                      :)J


                                    • joshbensadon
                                      ... It has lots of great detail, but it s missing the one detail about the sequence of the nibblizing. It tells you that the bits are taken all apart, but it
                                      Message 18 of 20 , Jun 3, 2013
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                                        --- In midatlanticretro@yahoogroups.com, Andrew Molloy <awmolloy@...> wrote:
                                        >
                                        > Not positive, but I think Beneath Apple DOS covers it.
                                        >
                                        > http://archive.org/details/Beneath_Apple_DOS
                                        >
                                        > Andy

                                        It has lots of great detail, but it's missing the one detail about the sequence of the nibblizing. It tells you that the bits are taken all apart, but it doesn't say exactly where they all go. Small detail, but computers are all about details.

                                        :)J
                                      • Mike
                                        Here is the nibblizing code for write for DOS 3.3 ... I added the comments. You should be able to figure it out from this code snippet. I m pretty sure the 86
                                        Message 19 of 20 , Jun 4, 2013
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                                          Here is the nibblizing code for write for DOS 3.3 ... I added the comments.
                                          You should be able to figure it out from this code snippet.
                                          I'm pretty sure the 86 (6 bit)bytes are written to disk first and the other 256 (6 bit)bytes second after being transformed to 8 bit codes suitable for the disk driver through a simple lookup into a 64 byte table.

                                          B800- A2 00 LDX #$00
                                          B802- A0 02 LDY #$02
                                          B804- 88 DEY
                                          B805- B1 3E LDA ($3E),Y ; fetch byte from source buffer (starting at end of buffer)
                                          B807- 4A LSR ; shift LSb to carry
                                          B808- 3E 00 BC ROL $BC00,X ; shift LSb into destination
                                          B80B- 4A LSR ; shift next LSb to carry (6 MSB bits remain from input byte)
                                          B80C- 3E 00 BC ROL $BC00,X ; shift next LSb into destination
                                          B80F- 99 00 BB STA $BB00,Y ; store remaining 6 bits
                                          B812- E8 INX ; point to next buffer (for merged 2 LSb buffer)
                                          B813- E0 56 CPX #$56 ; 86 bytes processed?
                                          B815- 90 ED BCC $B804 ; no continue
                                          B817- A2 00 LDX #$00 ; yes, start again at top of merged 2 LSb buffe)
                                          B819- 98 TYA
                                          B81A- D0 E8 BNE $B804 ; finished all 256 bytes?
                                          B81C- A2 55 LDX #$55 ; yes, clear 2 MSb of each byte of 86 byte buffer
                                          B81E- BD 00 BC LDA $BC00,X ;
                                          B821- 29 3F AND #$3F
                                          B823- 9D 00 BC STA $BC00,X
                                          B826- CA DEX
                                          B827- 10 F5 BPL $B81E ; all done?
                                          B829- 60 RTS ; yes




                                          --- In midatlanticretro@yahoogroups.com, joshbensadon <no_reply@...> wrote:
                                          >
                                          >
                                          >
                                          > --- In midatlanticretro@yahoogroups.com, Andrew Molloy <awmolloy@> wrote:
                                          > >
                                          > > Not positive, but I think Beneath Apple DOS covers it.
                                          > >
                                          > > http://archive.org/details/Beneath_Apple_DOS
                                          > >
                                          > > Andy
                                          >
                                          > It has lots of great detail, but it's missing the one detail about the sequence of the nibblizing. It tells you that the bits are taken all apart, but it doesn't say exactly where they all go. Small detail, but computers are all about details.
                                          >
                                          > :)J
                                          >
                                        • joshbensadon
                                          ... Thanks Mike, that s EXACTLY what I needed to know. The book doesn t tell you that the sequence of double bits continues for 86 bytes, then is repeated in
                                          Message 20 of 20 , Jun 4, 2013
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                                            --- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
                                            >
                                            > Here is the nibblizing code for write for DOS 3.3 ... I added the comments.


                                            Thanks Mike, that's EXACTLY what I needed to know. The book doesn't tell you that the sequence of double bits continues for 86 bytes, then is repeated in the next column for the next 86 bytes and repeated again for the last 84 bytes to round up 256 total.

                                            It does give the order of these bytes when sent to the disk and you are right to say it sends the 86 byte secondary (nibble) buffer first.

                                            Thanks again, it's much appreciated.

                                            :)J
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