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CPM on 8800 using original Altair floppy

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  • deramp5113
    Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I d like to see the CBIOS source, but even a
    Message 1 of 14 , Jan 9, 2013
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      Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.

      The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.

      Thanks!
    • Craig Landrum
      ... Several years ago one of the members of this forum provided me with an 8 inch diskette copy of Burcom CP/M 2.2 which worked great on my Altair 8800 with
      Message 2 of 14 , Jan 9, 2013
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        On 1/9/13 at 12:46 PM, deramp5113@... (deramp5113) wrote:

        >Does anyone have a copy of CPM 2.2 running on an 8800 using the
        >original Altair floppy drive (88-DCDD)?

        Several years ago one of the members of this forum provided me
        with an
        8 inch diskette copy of Burcom CP/M 2.2 which worked great on my Altair
        8800 with the original floppy drives. I'm sorry to say I no
        longer have
        that system or software nor do I recall the name of the person
        who provided
        it, but that diskette is probably the one you want.

        --
        Craig Landrum
        Chief Technical Officer
        mindwrap, inc.
        Phone: (540) 347-2552 x 229
        Fax: (540) 347-2556
        email: craigl@...
      • stuartawyatt
        It s been 40+ years since I stepped through that code, but I think it was a tight loop for the sector hole, then read two bytes at a time inline and then
        Message 3 of 14 , Jan 10, 2013
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          It's been 40+ years since I stepped through that code, but I think it was a tight loop for the sector hole, then read two bytes at a time inline and then looped around that code.

          If no one else has the code, I might have it printed out somewhere.

          -Stuart

          --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
          >
          > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.
          >
          > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.
          >
          > Thanks!
          >
        • Dave Sroelov
          i ll take a look for it as well. it s buried in a box here somewhere. it was a very tight loop. from what i remember, the controller spits out a byte every
          Message 4 of 14 , Jan 11, 2013
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            i'll take a look for it as well. it's buried in a box here somewhere.

            it was a very tight loop. from what i remember, the controller spits
            out a byte every 32 microseconds. if you read it one by at a time, the
            8080 2MHz timing was something like 31.5 microseconds per loop, which
            was cutting things really close. i wrote a single byte loop for my
            machine and i never had a problem, but if your machine was a teeny bit
            slow, you could easily miss a byte.

            the two-byte loop searched waited for the index hole, then read two
            bytes every time the "byte ready" flag came up. of course, if your
            machine was just a teeny bit fast, you could try reading second byte
            before it was all there.

            this kind of loop was also the reason why a lot of MITS software
            wouldn't run properly if you tossed in a 4MHz Z-80.
          • B Degnan
            There s a 680 on Ebay. Looks good, round paddles. Bill
            Message 5 of 14 , Jan 11, 2013
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              There's a 680 on Ebay.  Looks good, round paddles.
              Bill
            • steve
              I guess he s referring to this one, with bat-handle switches: http://www.ebay.com/itm/321053564606 Too bad there are no internal photos. I worked with several
              Message 6 of 14 , Jan 11, 2013
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                I guess he's referring to this one, with bat-handle switches:
                http://www.ebay.com/itm/321053564606
                Too bad there are no internal photos.

                I worked with several of the people whose names are on the QC tags. The guy who wrote "OK" on the front panel sticker was a very good tech. If he said it was OK, it was (35 years ago).

                steve
                ======================================

                --- In altaircomputerclub@yahoogroups.com, B Degnan wrote:
                >
                > There's a 680 on Ebay. Looks good, round paddles.
                > Bill
                >
              • W Tom
                Here is the MBASIC4 Program used to capture the CBIOS. 1 GETBIOS - CP/M MBASIC4 10 CLEAR 10000: WIDTH 80 20 SA# = &HE600 BIOS Start Address for 60K MITS CP/M
                Message 7 of 14 , Jan 18, 2013
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                  Here is the MBASIC4 Program used to capture the CBIOS.

                  1 'GETBIOS - CP/M MBASIC4
                  10 CLEAR 10000: WIDTH 80
                  20 SA# = &HE600 'BIOS Start Address for 60K MITS CP/M
                  30 CS% = &HD00 'Code Size for BIOS
                  100 PRINT: PRINT "GETBIOS " + HEX$(SA#) + STR$(CS%) + " byte code save program"
                  110 PRINT "Version 1.1, 16Jan13
                  120 PRINT "Copyright 2010-2012, William Thomas Sanderson:
                  130 PRINT "www.virtualaltair.com": PRINT
                  200 LINE INPUT "Enter output file name without extension -->"; F$
                  220 IF F$="" THEN GOTO 999
                  250 OPEN "O", #1, F$ + ".TXT" 'Text output file
                  260 'OPEN "O", #2, F$ + ".HEX" 'HEX output file
                  300 FOR O%=0 TO (CS%-1)
                  310 BY% = PEEK(SA#+O%) 'Get byte of memory
                  320 BY$ = RIGHT$(STR$(BY%), (LEN(STR$(BY%))-1)) ' Remove leading blank
                  330 BY$ = RIGHT$(("00"+BY$), 3) 'Add leading zeros
                  340 BH$ = RIGHT$(("0"+HEX$(BY%)), 2) ' HEX value with leading zeros
                  350 BO$ = RIGHT$(("00"+OCT$(BY%)), 3) 'Octal value with leading zero
                  360 A# = SA# + O% ' Address = Start Address + Offset
                  370 AO$ = RIGHT$(("00000" + OCT$(A#)),6) 'Octal Address with leading zeros
                  380 AH$ = RIGHT$(("000" + HEX$(A#)), 4) 'Hex Address with leading zeros
                  460 PRINT BY$, BH$, BO$, AH$, AO$
                  470 PRINT #1, BY$, BH$, BO$, AH$, AO$
                  480 ' PRINT #2, CHR$(BY%);
                  490 NEXT O%
                  900 CLOSE
                  990 PRINT: PRINT "DONE"
                  999 END
                  Ok


                  --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                  >
                  > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.
                  >
                  > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.
                  >
                  > Thanks!
                  >
                • deramp5113
                  Thanks to W Tom for memory dumps of the BIOS of Burcom CPM 2.2! As suspected (since the Burcom CPM works with a real drive), the disk write logic in the Burcom
                  Message 8 of 14 , Jan 19, 2013
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                    Thanks to W Tom for memory dumps of the BIOS of Burcom CPM 2.2!

                    As suspected (since the Burcom CPM works with a real drive), the disk write logic in the Burcom CPM eliminates the large delay between "write enable" and output of write data that is present in the Altair32 and SimH implementations of the BIOS. This long delay (the entire output buffer is copied from from one location to another between the time "write enable" is issued and the first byte is written) prevents these versions of the BIOS from working on a real drive.

                    My second issue with the emulator BIOS's was the fact the head was unloaded after every sector access. This would turn a real drive into a machine gun while booting or reading large files. Sure enough, in the Burcom BIOS, the head is left loaded until console input is requested. This seems like a good point to unload the head since disk i/o must be complete if software is to the point of looking for operator input.

                    I'll recreate a commented source of the Burcom BIOS as I find time. This source can then be used to create new copies of CPM that are compatible with the Altair 8800 and original Altair floppy drives.


                    --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                    >
                    > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.
                    >
                    > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.
                    >
                    > Thanks!
                    >
                  • steve
                    Deramp s machine gun sound reminds me of a program going around at MITS that would load and unload the head of an 8 drive, at a speed that increased from a
                    Message 9 of 14 , Jan 19, 2013
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                      Deramp's "machine gun" sound reminds me of a program going around at MITS that would load and unload the head of an 8" drive, at a speed that increased from a relatively slow rate (maybe ~500mS/cycle) to a much faster rate at the limit of the head load solenoid's response, and then slower again. It kind of sounded like a hot rod reving its engine. It wasn't very kind to the head or the diskette, but fun to do, nonetheless.

                      I wrote another little program that would energize/de-energize a UIO board's onboard relay at different frequencies depending on what key I pressed on the keyboard. It amounted to a kind of musical buzzer that one could use to play simple tunes. The program was not much more than a bunch of for-next loops. You could do the same thing with an ACR cassette interface board set.

                      steve
                      ======================


                      --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                      >
                      > Thanks to W Tom for memory dumps of the BIOS of Burcom CPM 2.2!
                      >
                      > As suspected (since the Burcom CPM works with a real drive), the disk write logic in the Burcom CPM eliminates the large delay between "write enable" and output of write data that is present in the Altair32 and SimH implementations of the BIOS. This long delay (the entire output buffer is copied from from one location to another between the time "write enable" is issued and the first byte is written) prevents these versions of the BIOS from working on a real drive.
                      >
                      > My second issue with the emulator BIOS's was the fact the head was unloaded after every sector access. This would turn a real drive into a machine gun while booting or reading large files. Sure enough, in the Burcom BIOS, the head is left loaded until console input is requested. This seems like a good point to unload the head since disk i/o must be complete if software is to the point of looking for operator input.
                      >
                      > I'll recreate a commented source of the Burcom BIOS as I find time. This source can then be used to create new copies of CPM that are compatible with the Altair 8800 and original Altair floppy drives.
                      >
                      >
                      > --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                      > >
                      > > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.
                      > >
                      > > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.
                      > >
                      > > Thanks!
                      > >
                      >
                    • deramp5113
                      Status update: It appears that one of the few, if not the only, version of CPM 2.2 running on the original Altair floppy drive (88-DCDD) was Burcon CPM. I
                      Message 10 of 14 , Jan 30, 2013
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                        Status update:

                        It appears that one of the few, if not the only, version of CPM 2.2 running on the original Altair floppy drive (88-DCDD) was "Burcon CPM." I have finished creating a fully documented source of the BIOS for the Burcon CPM by diassembling a memory dump provided by W Tom.

                        With the Burcon BIOS source, I can now generate a Burcon CPM of any memory size for the Altair disk drive.

                        There are a couple of minor bugs in the Burcon BIOS, so a slightly modified version of the BIOS may also be in order.

                        The Burcon BIOS, which runs fine on real hardware, did not run under the Altair32 or SIMH emulators. After some digging, I found a bug in the floppy drive emulation code of both of the emulators. After fixing the bug and recompiling the emulators from source, both emulators now work with the Burcon disk image.

                        The SIMH emulator still has a problem in that SIMH's boot ROM won't boot the Burcon disk. The loader on the Burcon disk is only two sectors long, but the SIMH boot ROM code doesn't properly read the 256 bytes of the loader into memory. The SIMH emulator will boot the Burcon disk just fine if I install the original Altair boot ROM or the modified Altair32 emulator's boot ROM instead. I haven't bothered digging into the SIMH boot ROM code yet to find out why.

                        Finally, I've written programs to image any Altair floppy to a file on a PC via a serial port, and the inverse operation to create an Altair floppy from a disk image file saved on a PC. This program will image any Altair disk independent of what software created it.



                        --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                        >
                        > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK.
                        >
                        > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded.
                        >
                        > Thanks!
                        >
                      • B Degnan
                        Wow that s great. Perhaps you could post the paper tape image to the files section? I d love to try it out. ... From: deramp5113 To:
                        Message 11 of 14 , Jan 30, 2013
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                          Wow that's great.  Perhaps you could post the "paper tape" image to the files section?  I'd love to try it out.



                          -----Original Message-----
                          From: deramp5113 <deramp5113@...>
                          To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                          Sent: Wed, Jan 30, 2013 11:14 am
                          Subject: [Altair Computer Club] Re: CPM on 8800 using original Altair floppy

                          Status update:
                          
                          It appears that one of the few, if not the only, version of CPM 2.2 running on 
                          the original Altair floppy drive (88-DCDD) was "Burcon CPM." I have finished 
                          creating a fully documented source of the BIOS for the Burcon CPM by 
                          diassembling a memory dump provided by W Tom.
                          
                          With the Burcon BIOS source, I can now generate a Burcon CPM of any memory size 
                          for the Altair disk drive. 
                          
                          There are a couple of minor bugs in the Burcon BIOS, so a slightly modified 
                          version of the BIOS may also be in order.
                          
                          The Burcon BIOS, which runs fine on real hardware, did not run under the 
                          Altair32 or SIMH emulators. After some digging, I found a bug in the floppy 
                          drive emulation code of both of the emulators. After fixing the bug and 
                          recompiling the emulators from source, both emulators now work with the Burcon 
                          disk image.
                          
                          The SIMH emulator still has a problem in that SIMH's boot ROM won't boot the 
                          Burcon disk. The loader on the Burcon disk is only two sectors long, but the 
                          SIMH boot ROM code doesn't properly read the 256 bytes of the loader into 
                          memory. The SIMH emulator will boot the Burcon disk just fine if I install the 
                          original Altair boot ROM or the modified Altair32 emulator's boot ROM instead. I 
                          haven't bothered digging into the SIMH boot ROM code yet to find out why.
                          
                          Finally, I've written programs to image any Altair floppy to a file on a PC via 
                          a serial port, and the inverse operation to create an Altair floppy from a disk 
                          image file saved on a PC. This program will image any Altair disk independent of 
                          what software created it.
                          
                          
                          
                          
                          --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote: > > Does anyone have a copy of CPM 2.2 running on an 8800 using the original Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but even a binary version of the whole thing is OK. > > The CBIOS written for the Altair32 and Simh emulators, though coded for an emulation of the 88-DCDD floppy, does not work with a real floppy drive (the write timing from sector detect to the start of data output is way too long). I have updated the CBIOS to work with a real drive, but I'm curious how the "original" versions were coded. > > Thanks! > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/altaircomputerclub/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/altaircomputerclub/join (Yahoo! ID required) <*> To change settings via email: altaircomputerclub-digest@yahoogroups.com altaircomputerclub-fullfeatured@yahoogroups.com <*> To unsubscribe from this group, send an email to: altaircomputerclub-unsubscribe@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
                        • deramp5113
                          I ll post an image of a drive or two soon. Sounds like altair32 and simh emulators will update soon to fix disk emulation issues. Simh may host a version of
                          Message 12 of 14 , Jan 31, 2013
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                            I'll post an image of a drive or two soon. Sounds like altair32 and simh emulators will update soon to fix disk emulation issues. Simh may host a version of the MITS Burcon disk as well.


                            --- In altaircomputerclub@yahoogroups.com, B Degnan wrote:
                            >
                            > Wow that's great. Perhaps you could post the "paper tape" image to the files section? I'd love to try it out.
                            >
                            >
                            >

                            >
                            > -----Original Message-----
                            > From: deramp5113
                            > To: altaircomputerclub
                            > Sent: Wed, Jan 30, 2013 11:14 am
                            > Subject: [Altair Computer Club] Re: CPM on 8800 using original Altair floppy
                            >
                            >
                            > Status update:
                            >
                            > It appears that one of the few, if not the only, version of CPM 2.2 running on
                            > the original Altair floppy drive (88-DCDD) was "Burcon CPM." I have finished
                            > creating a fully documented source of the BIOS for the Burcon CPM by
                            > diassembling a memory dump provided by W Tom.
                            >
                            > With the Burcon BIOS source, I can now generate a Burcon CPM of any memory size
                            > for the Altair disk drive.
                            >
                            > There are a couple of minor bugs in the Burcon BIOS, so a slightly modified
                            > version of the BIOS may also be in order.
                            >
                            > The Burcon BIOS, which runs fine on real hardware, did not run under the
                            > Altair32 or SIMH emulators. After some digging, I found a bug in the floppy
                            > drive emulation code of both of the emulators. After fixing the bug and
                            > recompiling the emulators from source, both emulators now work with the Burcon
                            > disk image.
                            >
                            > The SIMH emulator still has a problem in that SIMH's boot ROM won't boot the
                            > Burcon disk. The loader on the Burcon disk is only two sectors long, but the
                            > SIMH boot ROM code doesn't properly read the 256 bytes of the loader into
                            > memory. The SIMH emulator will boot the Burcon disk just fine if I install the
                            > original Altair boot ROM or the modified Altair32 emulator's boot ROM instead. I
                            > haven't bothered digging into the SIMH boot ROM code yet to find out why.
                            >
                            > Finally, I've written programs to image any Altair floppy to a file on a PC via
                            > a serial port, and the inverse operation to create an Altair floppy from a disk
                            > image file saved on a PC. This program will image any Altair disk independent of
                            > what software created it.
                            >
                            >
                            >
                            > --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                            > >
                            > > Does anyone have a copy of CPM 2.2 running on an 8800 using the original
                            > Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but
                            > even a binary version of the whole thing is OK.
                            > >
                            > > The CBIOS written for the Altair32 and Simh emulators, though coded for an
                            > emulation of the 88-DCDD floppy, does not work with a real floppy drive (the
                            > write timing from sector detect to the start of data output is way too long). I
                            > have updated the CBIOS to work with a real drive, but I'm curious how the
                            > "original" versions were coded.
                            > >
                            > > Thanks!
                            > >
                            >
                            >
                            >
                            >
                            > ------------------------------------
                            >
                            > Yahoo! Groups Links
                            >
                          • W Tom
                            Now that we can capture Altair diskettes, I d like to run Altair accounting software on an Altair emulator. The Altair accounting software uses BASIC with
                            Message 13 of 14 , Feb 2, 2013
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                              Now that we can capture Altair diskettes, I'd like to run Altair accounting software on an Altair emulator. The Altair accounting software uses BASIC with Memory set to 59000. The software puts printer drivers above BASIC.

                              Do the emulators provide a full 64K RAM after boot like an 8800bt?


                              W Tom S
                              --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                              >
                              > I'll post an image of a drive or two soon. Sounds like altair32 and simh emulators will update soon to fix disk emulation issues. Simh may host a version of the MITS Burcon disk as well.
                              >
                              >
                              > --- In altaircomputerclub@yahoogroups.com, B Degnan wrote:
                              > >
                              > > Wow that's great. Perhaps you could post the "paper tape" image to the files section? I'd love to try it out.
                              > >
                              > >
                              > >
                              >
                              > >
                              > > -----Original Message-----
                              > > From: deramp5113
                              > > To: altaircomputerclub
                              > > Sent: Wed, Jan 30, 2013 11:14 am
                              > > Subject: [Altair Computer Club] Re: CPM on 8800 using original Altair floppy
                              > >
                              > >
                              > > Status update:
                              > >
                              > > It appears that one of the few, if not the only, version of CPM 2.2 running on
                              > > the original Altair floppy drive (88-DCDD) was "Burcon CPM." I have finished
                              > > creating a fully documented source of the BIOS for the Burcon CPM by
                              > > diassembling a memory dump provided by W Tom.
                              > >
                              > > With the Burcon BIOS source, I can now generate a Burcon CPM of any memory size
                              > > for the Altair disk drive.
                              > >
                              > > There are a couple of minor bugs in the Burcon BIOS, so a slightly modified
                              > > version of the BIOS may also be in order.
                              > >
                              > > The Burcon BIOS, which runs fine on real hardware, did not run under the
                              > > Altair32 or SIMH emulators. After some digging, I found a bug in the floppy
                              > > drive emulation code of both of the emulators. After fixing the bug and
                              > > recompiling the emulators from source, both emulators now work with the Burcon
                              > > disk image.
                              > >
                              > > The SIMH emulator still has a problem in that SIMH's boot ROM won't boot the
                              > > Burcon disk. The loader on the Burcon disk is only two sectors long, but the
                              > > SIMH boot ROM code doesn't properly read the 256 bytes of the loader into
                              > > memory. The SIMH emulator will boot the Burcon disk just fine if I install the
                              > > original Altair boot ROM or the modified Altair32 emulator's boot ROM instead. I
                              > > haven't bothered digging into the SIMH boot ROM code yet to find out why.
                              > >
                              > > Finally, I've written programs to image any Altair floppy to a file on a PC via
                              > > a serial port, and the inverse operation to create an Altair floppy from a disk
                              > > image file saved on a PC. This program will image any Altair disk independent of
                              > > what software created it.
                              > >
                              > >
                              > >
                              > > --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                              > > >
                              > > > Does anyone have a copy of CPM 2.2 running on an 8800 using the original
                              > > Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but
                              > > even a binary version of the whole thing is OK.
                              > > >
                              > > > The CBIOS written for the Altair32 and Simh emulators, though coded for an
                              > > emulation of the 88-DCDD floppy, does not work with a real floppy drive (the
                              > > write timing from sector detect to the start of data output is way too long). I
                              > > have updated the CBIOS to work with a real drive, but I'm curious how the
                              > > "original" versions were coded.
                              > > >
                              > > > Thanks!
                              > > >
                              > >
                              > >
                              > >
                              > >
                              > > ------------------------------------
                              > >
                              > > Yahoo! Groups Links
                              > >
                              >
                            • deramp5113
                              Yes, you can configure the emulators for a full 64K of RAM and have the 256 byte disk boot ROM actually be RAM so it s bit of space can be used after
                              Message 14 of 14 , Feb 2, 2013
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                                Yes, you can configure the emulators for a full 64K of RAM and have the 256 byte disk boot "ROM" actually be RAM so it's bit of space can be used after booting.



                                --- In altaircomputerclub@yahoogroups.com, "W Tom" wrote:
                                >
                                > Now that we can capture Altair diskettes, I'd like to run Altair accounting software on an Altair emulator. The Altair accounting software uses BASIC with Memory set to 59000. The software puts printer drivers above BASIC.
                                >
                                > Do the emulators provide a full 64K RAM after boot like an 8800bt?
                                >
                                >
                                > W Tom S
                                > --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                                > >
                                > > I'll post an image of a drive or two soon. Sounds like altair32 and simh emulators will update soon to fix disk emulation issues. Simh may host a version of the MITS Burcon disk as well.
                                > >
                                > >
                                > > --- In altaircomputerclub@yahoogroups.com, B Degnan wrote:
                                > > >
                                > > > Wow that's great. Perhaps you could post the "paper tape" image to the files section? I'd love to try it out.
                                > > >
                                > > >
                                > > >
                                > >
                                > > >
                                > > > -----Original Message-----
                                > > > From: deramp5113
                                > > > To: altaircomputerclub
                                > > > Sent: Wed, Jan 30, 2013 11:14 am
                                > > > Subject: [Altair Computer Club] Re: CPM on 8800 using original Altair floppy
                                > > >
                                > > >
                                > > > Status update:
                                > > >
                                > > > It appears that one of the few, if not the only, version of CPM 2.2 running on
                                > > > the original Altair floppy drive (88-DCDD) was "Burcon CPM." I have finished
                                > > > creating a fully documented source of the BIOS for the Burcon CPM by
                                > > > diassembling a memory dump provided by W Tom.
                                > > >
                                > > > With the Burcon BIOS source, I can now generate a Burcon CPM of any memory size
                                > > > for the Altair disk drive.
                                > > >
                                > > > There are a couple of minor bugs in the Burcon BIOS, so a slightly modified
                                > > > version of the BIOS may also be in order.
                                > > >
                                > > > The Burcon BIOS, which runs fine on real hardware, did not run under the
                                > > > Altair32 or SIMH emulators. After some digging, I found a bug in the floppy
                                > > > drive emulation code of both of the emulators. After fixing the bug and
                                > > > recompiling the emulators from source, both emulators now work with the Burcon
                                > > > disk image.
                                > > >
                                > > > The SIMH emulator still has a problem in that SIMH's boot ROM won't boot the
                                > > > Burcon disk. The loader on the Burcon disk is only two sectors long, but the
                                > > > SIMH boot ROM code doesn't properly read the 256 bytes of the loader into
                                > > > memory. The SIMH emulator will boot the Burcon disk just fine if I install the
                                > > > original Altair boot ROM or the modified Altair32 emulator's boot ROM instead. I
                                > > > haven't bothered digging into the SIMH boot ROM code yet to find out why.
                                > > >
                                > > > Finally, I've written programs to image any Altair floppy to a file on a PC via
                                > > > a serial port, and the inverse operation to create an Altair floppy from a disk
                                > > > image file saved on a PC. This program will image any Altair disk independent of
                                > > > what software created it.
                                > > >
                                > > >
                                > > >
                                > > > --- In altaircomputerclub@yahoogroups.com, "deramp5113" wrote:
                                > > > >
                                > > > > Does anyone have a copy of CPM 2.2 running on an 8800 using the original
                                > > > Altair floppy drive (88-DCDD)? Ideally, I'd like to see the CBIOS source, but
                                > > > even a binary version of the whole thing is OK.
                                > > > >
                                > > > > The CBIOS written for the Altair32 and Simh emulators, though coded for an
                                > > > emulation of the 88-DCDD floppy, does not work with a real floppy drive (the
                                > > > write timing from sector detect to the start of data output is way too long). I
                                > > > have updated the CBIOS to work with a real drive, but I'm curious how the
                                > > > "original" versions were coded.
                                > > > >
                                > > > > Thanks!
                                > > > >
                                > > >
                                > > >
                                > > >
                                > > >
                                > > > ------------------------------------
                                > > >
                                > > > Yahoo! Groups Links
                                > > >
                                > >
                                >
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