--- In midatlanticretro@yahoogroups.com, "billdeg"  wrote:
>
> I feel as if you're missing the point of the Altair, you're not supposed to
have it so easy.  :-) Loading BASIC with papertape took almost an hour before
you programmed the first line of BASIC code.
>

Hi Bill,

Did it really take nearly an hour to load the paper tape?
I have a paper tape reader and it doesn't take long to go through a role of
tape.  But then again, it's a modern paper tape reader, 300 baud output.  If you
have 4K basic, divided by 30 chars per second, that's only a few minutes.

I'm not doubting you, I just would like to hear the details about why it took
nearly an hour.... oh, I guess you have to toggle in the boot strap? But that's
only 16 bytes? And after doing it a dozen times on my IMSAI, I had that
memorized.

Cheers,
Josh

I think Bill wasn't complete in his explanation of "backspace".  Yes it's
unsupported, but 4k basic supports "rub out".  Which is what makes the vintage
feeling when using the altair with basic cool.  Rubout is simply an underscore
to erase the last character.  However it looks like this on a monitor.  I'm not
sure if a teletype backs up and strikes out the character, I can just tell you
what happens on the altair when on terminal.

For exc_ample....

10 prr_int "hellll__o"

Is actually read as

10 print "hello"

Since most "modern" people tend to hit the delete key not underscore, just map
it to that.

Btw, since the altair isn't the only vintage machine like this, the apple-1 is
the same, so it must have been normal back then.  On the Apple though the most
common keyboard was a Datanetics which didn't have an underscore unless you hard
wired one with jumpers, people I guess never used it much.  Me my typing sucks,
so how to "rub out" a character, is one of the first things I try to figure out
on a platform.

Fyi, Also I can't seem to get you simulator to work on my iPad...

Cheers,
Corey


--- In midatlanticretro@yahoogroups.com, "who88777"  wrote:
>
> I would still like for backspace to not leave the page even if it won't be
read properly by the software.
>
> Paste is obviously not a feature of the original altair, but when pasting it
should simulate typing of characters.  The only way you will be able to load new
software onto the emulated altair is through my program to read hex files from
the terminal.  It would be very tedious to do so without copy and paste working.
Ditto for large BASIC programs.
>
> The memory map is as follows after boot:
> 0x0000 - JMP 0x8000 program
> 0x4000 - End of RAM and top of stack for menu/loader (it automatically seeks
the end of memory to set SP)
> 0x8000 - Start of loader program ROM
> 0x????? - End of ROM varies based on code size.  It is over 20K because of the
ASCII art
>
> When loading altair BASIC or other programs the image is copied into memory
and a JMP is executed to the base address.  To save time for pre-loaded software
the emulator itself memcpy's it into RAM via a command through port 250. If you
use my hex-loader then the emulated CPU is doing all the work.
>
> The base address for the Altair BASIC is 0x0000.  You could reach the loader
again if you can execute a JMP 0x8000 but its not expected you will ever get
back.
>
> The BASIC image I have is the one from SIMH.  I also saw the 8K version but
have been unable to get it to work.  If I ever get around to emulating a disk
drive I would like to see CP/M running.
>
> --- In midatlanticretro@yahoogroups.com, "B. Degnan"  wrote:
> >
> >
> > > A few known issues:- Backspace doesn't work in the terminal- Paste
> > > doesn't work in the terminal- Some layout issues on Safari- LEDs operate
> > > more like hollywood computer lights rather than the PWM you'd see on the
> > > real thing- Switches on the control panel don't look like the originals
> > > (If somebody can get me a straight on photo of the Altair with switches
> > > in various positions I could fix this)
> >
> > The backspace key does not work on the real terminal when using 4K BASIC.
> > You may be able to backspace but then you'll get an error.  So you're ok.
> >  why *would* paste work?
> >
> > what is the memory map of BASIC after successful load?
> >
> > Bill
> >

On Tue, Jan 08, 2013 at 12:34:03PM -0000, corey986 wrote:
>
> I think Bill wasn't complete in his explanation of "backspace".  Yes it's
> unsupported, but 4k basic supports "rub out".  Which is what makes the
> vintage feeling when using the altair with basic cool.  Rubout is
> simply an underscore to erase the last character.
> However it looks like this on a monitor.  I'm not sure if a teletype
> backs up and strikes out the character, I can just tell you what happens
> on the altair when on terminal.
>
> For exc_ample....
>
> 10 prr_int "hellll__o"
>
> Is actually read as
>
> 10 print "hello"
>
On the Altair do you actually use the _ key for deleting a character? On a
teletype they normally used the rubout key that gave code 127. On modern
keyvoards that is normally the delete key and backspace used code 8.
The teletype doesn't have a backspace key though you can generate the
code with control-h.
(Rubout third row third from right)
http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large

THe printing _ is because of teletypes. A teletype can't back up other than
a carrage return. Even if it did you wouldn't be able to reliably read
the new character printed on top of the old so they printed the underscore
for each character "backed up". On the PDP-8 you use the delete key and
it prints the _ when configured for teletype.

> ----------------------------------------------
> Start the clock:
>
> First set up the physical connection between teletype and computer, then test
RAM to be sure you have a working system. Next toggle in the boot strap and
verify it’s in RAM.   Carefully insert the absolute loader tape in the
teletype reader.  Run the bootstrap loaded.  wait for the abs loader to be read
in.  check to be sure it is loaded into RAM.   Then remove abs loader tape, and
set up BASIC tape in reader. run abs loader and read in basic tape.   If you are
ok the basic program will automatically start up when tape finishes.   
Otherwise you can check the beginning and end of the RAM space used by BASIC
hoping only the first few hex commands were missing and correct the values
manually and run manually.
>
>
>
> 1 hour is reasonable.  Hard to complete in less than 30 mins.


Hi Bill,

Yeah, I guess on a change of venue it would take the hour or probably more
depending on the failure(s), but on a day to day process, the equipment might
already be set up, the programmer might already trust the RAM, etc.  Actually,
day to day, I might guess the machine would be left on over night?  New
question, did the programmer save his/her work on to paper tape? How often I
wonder?

I can only relate to starting up a Data General computer, DG1 I think.  I had to
enter a 77 byte tape boot loader manually from a terminal, then play a micro
cassette.  It was a boat anchor 20 years ago, but I wish I had the foresight to
keep it.  My customer kept their machine running 24/7, they even had a UPS for
it.  The UPS was something to see in itself.  Three separate parts, Battery
charger, Batteries and the Inverter.

Note, after entering the 77 byte boot loader a few times, I wrote a program on
the TRS-80 model 100 to send those 77 bytes for me.  That was a great relief!

Cheers,
Josh

> >
> On the Altair do you actually use the _ key for deleting a character? On
a
> teletype they normally used the rubout key that gave code 127. On modern

> keyvoards that is normally the delete key and backspace used code 8.
> The teletype doesn't have a backspace key though you can generate the
> code with control-h.
> (Rubout third row third from right)
> http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large
>
> THe printing _ is because of teletypes. A teletype can't back up other
than
> a carrage return. Even if it did you wouldn't be able to reliably read
> the new character printed on top of the old so they printed the
underscore
> for each character "backed up". On the PDP-8 you use the delete key and
> it prints the _ when configured for teletype.
>

In PDP 8 OS/8 using a glass vt102 terminal with a backspace key, under
standard configuration, use of backspace will generate an error even if
your command looks correct before you hit enter

If you type this..
.RUN RKA0;

..and then use the backspace key to correct (change semi-colon to
colon)...
.RUN RKA0:BASIC.SV [enter]

...OS/8 will return an OS syntax error.

My original point -  you can find a way to add backspace ability, but it
was not really an option back then so you have to decide whether it matters
to you or not to bypass the historic limitation of the time.

I believe that there is value to experience what it was really like to work
in this environment without modern shortcuts.  If to engineer a new program
you are required to toggle bootstraps, load a tape, enter code by hand,
punch the tape on the teletype, and so on you'll start to change your
approach to programming.  The first thing you realize is that it's best to
try to write and debug as much of the code by hand before you enter into
the computer.  That's why a lot of Altair docs I have come upon have sheets
and sheets of pseudo code and hand-written listings along with the manuals.
  People did not use the computer to write and edit code like they do today,
too time consuming.  You had to be more precise in your data entry and more
organized in your approach.  No one would want to sit there for a half hour
to punch a tape, then another half hour to run the tape just to find a
single syntax error crashes the whole program.  That's why there were a lot
less people doing programming and hardware back then, this kind of work was
not for everyone.  It gives you a real appreciation for those people
(before my time btw) who did all of this stuff when it was new back then,
and what motivated the likes of Woz/Jobs to make something easier to use.

Not everyone has the luxury of walking up to a computer with a teletype. I
think it would be a great service if we had an exhibit / demo for MARCH's
museum to show people what it was like to use a teletype for I/O and
program storage. I would not recommend allowing the public to use it
though, it'd have to be a ready-to-go demo for someone that had an hour to
witness the entire process, maybe with a little lecture to kill time
between the tape loads/punches.

Bill

I 100% agree.  Having to "flip" switches or even type in the ocal/hex by hand
has made me a better programmer.  This actually came up at dinner last night
(I'm at training in Texas right now) where we were talking about the "old" days
and how people who lived through toggling in a boot loader on a PDP8 seemed to
be more efficient in their resource utilization as programmers than the guys who
started programming with Visual Basic who tend to be sloppy in memory and
resource usage.  It was a pretty heated converstation enhanced by wine and Fogo
de Chao "Meat" high....

Cheers,
Corey
--- In midatlanticretro@yahoogroups.com, "B. Degnan"  wrote:
>
>
> > >
> > On the Altair do you actually use the _ key for deleting a character? On
> a
> > teletype they normally used the rubout key that gave code 127. On modern
>
> > keyvoards that is normally the delete key and backspace used code 8.
> > The teletype doesn't have a backspace key though you can generate the
> > code with control-h.
> > (Rubout third row third from right)
> > http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large
> >
> > THe printing _ is because of teletypes. A teletype can't back up other
> than
> > a carrage return. Even if it did you wouldn't be able to reliably read
> > the new character printed on top of the old so they printed the
> underscore
> > for each character "backed up". On the PDP-8 you use the delete key and
> > it prints the _ when configured for teletype.
> >
>
> In PDP 8 OS/8 using a glass vt102 terminal with a backspace key, under
> standard configuration, use of backspace will generate an error even if
> your command looks correct before you hit enter
>
> If you type this..
> .RUN RKA0;
>
> ..and then use the backspace key to correct (change semi-colon to
> colon)...
> .RUN RKA0:BASIC.SV [enter]
>
> ...OS/8 will return an OS syntax error.
>
> My original point -  you can find a way to add backspace ability, but it
> was not really an option back then so you have to decide whether it matters
> to you or not to bypass the historic limitation of the time.
>
> I believe that there is value to experience what it was really like to work
> in this environment without modern shortcuts.  If to engineer a new program
> you are required to toggle bootstraps, load a tape, enter code by hand,
> punch the tape on the teletype, and so on you'll start to change your
> approach to programming.  The first thing you realize is that it's best to
> try to write and debug as much of the code by hand before you enter into
> the computer.  That's why a lot of Altair docs I have come upon have sheets
> and sheets of pseudo code and hand-written listings along with the manuals.
>  People did not use the computer to write and edit code like they do today,
> too time consuming.  You had to be more precise in your data entry and more
> organized in your approach.  No one would want to sit there for a half hour
> to punch a tape, then another half hour to run the tape just to find a
> single syntax error crashes the whole program.  That's why there were a lot
> less people doing programming and hardware back then, this kind of work was
> not for everyone.  It gives you a real appreciation for those people
> (before my time btw) who did all of this stuff when it was new back then,
> and what motivated the likes of Woz/Jobs to make something easier to use.
>
> Not everyone has the luxury of walking up to a computer with a teletype. I
> think it would be a great service if we had an exhibit / demo for MARCH's
> museum to show people what it was like to use a teletype for I/O and
> program storage. I would not recommend allowing the public to use it
> though, it'd have to be a ready-to-go demo for someone that had an hour to
> witness the entire process, maybe with a little lecture to kill time
> between the tape loads/punches.
>
> Bill
>

Hey Bill...

   I have an idea for VCF... I was thinking of bringing my Briel Altair to sit
next to my real one.  It's been modified to have an external serial emulating
the SIO-A.  If we build a current loop to RS232 adapter for the teletype, we
could let people toggle in a boot loader on the Briel. I have like 100 spare
switches so I'm not concerned about the public using the briel unlike the real
one where original orange case round switches are expensive and hard to find,
and the silk screen needs to be protected from wear and scratches for historical
reasons.

Cheers,
Corey

--- In midatlanticretro@yahoogroups.com, corey986  wrote:
>
>
> I 100% agree.  Having to "flip" switches or even type in the ocal/hex by hand
has made me a better programmer.  This actually came up at dinner last night
(I'm at training in Texas right now) where we were talking about the "old" days
and how people who lived through toggling in a boot loader on a PDP8 seemed to
be more efficient in their resource utilization as programmers than the guys who
started programming with Visual Basic who tend to be sloppy in memory and
resource usage.  It was a pretty heated converstation enhanced by wine and Fogo
de Chao "Meat" high....
>
> Cheers,
> Corey
> --- In midatlanticretro@yahoogroups.com, "B. Degnan"  wrote:
> >
> >
> > > >
> > > On the Altair do you actually use the _ key for deleting a character? On
> > a
> > > teletype they normally used the rubout key that gave code 127. On modern
> >
> > > keyvoards that is normally the delete key and backspace used code 8.
> > > The teletype doesn't have a backspace key though you can generate the
> > > code with control-h.
> > > (Rubout third row third from right)
> > > http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large
> > >
> > > THe printing _ is because of teletypes. A teletype can't back up other
> > than
> > > a carrage return. Even if it did you wouldn't be able to reliably read
> > > the new character printed on top of the old so they printed the
> > underscore
> > > for each character "backed up". On the PDP-8 you use the delete key and
> > > it prints the _ when configured for teletype.
> > >
> >
> > In PDP 8 OS/8 using a glass vt102 terminal with a backspace key, under
> > standard configuration, use of backspace will generate an error even if
> > your command looks correct before you hit enter
> >
> > If you type this..
> > .RUN RKA0;
> >
> > ..and then use the backspace key to correct (change semi-colon to
> > colon)...
> > .RUN RKA0:BASIC.SV [enter]
> >
> > ...OS/8 will return an OS syntax error.
> >
> > My original point -  you can find a way to add backspace ability, but it
> > was not really an option back then so you have to decide whether it matters
> > to you or not to bypass the historic limitation of the time.
> >
> > I believe that there is value to experience what it was really like to work
> > in this environment without modern shortcuts.  If to engineer a new program
> > you are required to toggle bootstraps, load a tape, enter code by hand,
> > punch the tape on the teletype, and so on you'll start to change your
> > approach to programming.  The first thing you realize is that it's best to
> > try to write and debug as much of the code by hand before you enter into
> > the computer.  That's why a lot of Altair docs I have come upon have sheets
> > and sheets of pseudo code and hand-written listings along with the manuals.
> >  People did not use the computer to write and edit code like they do today,
> > too time consuming.  You had to be more precise in your data entry and more
> > organized in your approach.  No one would want to sit there for a half hour
> > to punch a tape, then another half hour to run the tape just to find a
> > single syntax error crashes the whole program.  That's why there were a lot
> > less people doing programming and hardware back then, this kind of work was
> > not for everyone.  It gives you a real appreciation for those people
> > (before my time btw) who did all of this stuff when it was new back then,
> > and what motivated the likes of Woz/Jobs to make something easier to use.
> >
> > Not everyone has the luxury of walking up to a computer with a teletype. I
> > think it would be a great service if we had an exhibit / demo for MARCH's
> > museum to show people what it was like to use a teletype for I/O and
> > program storage. I would not recommend allowing the public to use it
> > though, it'd have to be a ready-to-go demo for someone that had an hour to
> > witness the entire process, maybe with a little lecture to kill time
> > between the tape loads/punches.
> >
> > Bill
> >
>

On Tue, 8 Jan 2013, corey986 wrote:

> I 100% agree.  Having to "flip" switches or even type in the ocal/hex by
> hand has made me a better programmer.  This actually came up at dinner
> last night (I'm at training in Texas right now) where we were talking
> about the "old" days and how people who lived through toggling in a boot
> loader on a PDP8 seemed to be more efficient in their resource
> utilization as programmers than the guys who started programming with
> Visual Basic who tend to be sloppy in memory and resource usage.

     It actually extends forward a bit to the micro era.  If you were
constrained to less than 64KB of RAM for your code (not considering
overlay techniques), you had to be very careful of your resource
management.  In a Turbo Pascal program I wrote in the mid-'80s on a TRS-80
Model 4 running Montezuma Micro CP/M, I managed to fit an in-memory
indexing scheme such that I could retrieve any record from the database
stored on floppy in less than 2 seconds.


Mike Loewen 		 mloewen@...
Old Technology       http://sturgeon.css.psu.edu/~mloewen/Oldtech/

On 01/08/2013 09:54 AM, corey986 wrote:
>
> I 100% agree. Having to "flip" switches or even type in the ocal/hex by hand
has made me a
> better programmer. This actually came up at dinner last night (I'm at training
in Texas
> right now) where we were talking about the "old" days and how people who lived
through
> toggling in a boot loader on a PDP8 seemed to be more efficient in their
resource
> utilization as programmers than the guys who started programming with Visual
Basic who
> tend to be sloppy in memory and resource usage. It was a pretty heated
converstation
> enhanced by wine and Fogo de Chao "Meat" high....

This holds true of any restricted env such as a uC with limited resources.

Of course when you've been around long enough and use larger computer resources
you start to think about other limited resources such as time. As an Engineer
(EE, System Engineer, etc.) you have to look at the overall picture .

But I do agree that folks who have had to live with tight limits tend to
be better overall Engineers.

--
Linux Home Automation         Neil Cherry       ncherry@...
http://www.linuxha.com/                         Main site
http://linuxha.blogspot.com/                    My HA Blog
Author of:     Linux Smart Homes For Dummies

The teletype in the museum was converted to rs232.  I don't know if it was
also upgraded to a baud faster than 110 8/n/2.  It should be possible to
punch a tape of BASIC from the web to the modified machine's punch, and
then load basic directly from the tape.  You'd need an absolute loader in
ROM or on tape as well.  You could use a switch box to hop over to a glass
terminal after the tape loads.

-------- Original Message --------
> From: "corey986" <no_reply@yahoogroups.com>
> Sent: Tuesday, January 08, 2013 10:35 AM
> To: midatlanticretro@yahoogroups.com
> Subject: [midatlanticretro] Re: Altair 8800 Web Emulator
>
> Hey Bill...
>
>   I have an idea for VCF... I was thinking of bringing my Briel Altair to
sit next to my real one.  It's been modified to have an external serial
emulating the SIO-A.  If we build a current loop to RS232 adapter for the
teletype, we could let people toggle in a boot loader on the Briel. I have
like 100 spare switches so I'm not concerned about the public using the
briel unlike the real one where original orange case round switches are
expensive and hard to find, and the silk screen needs to be protected from
wear and scratches for historical reasons.
>
> Cheers,
> Corey
>
> --- In midatlanticretro@yahoogroups.com, corey986  wrote:
> >
> >
> > I 100% agree.  Having to "flip" switches or even type in the ocal/hex
by hand has made me a better programmer.  This actually came up at dinner
last night (I'm at training in Texas right now) where we were talking about
the "old" days and how people who lived through toggling in a boot loader
on a PDP8 seemed to be more efficient in their resource utilization as
programmers than the guys who started programming with Visual Basic who
tend to be sloppy in memory and resource usage.  It was a pretty heated
converstation enhanced by wine and Fogo de Chao "Meat" high....
> >
> > Cheers,
> > Corey
> > --- In midatlanticretro@yahoogroups.com, "B. Degnan"  wrote:
> > >
> > >
> > > > >
> > > > On the Altair do you actually use the _ key for deleting a
character? On
> > > a
> > > > teletype they normally used the rubout key that gave code 127. On
modern
> > >
> > > > keyvoards that is normally the delete key and backspace used code
8.
> > > > The teletype doesn't have a backspace key though you can generate
the
> > > > code with control-h.
> > > > (Rubout third row third from right)
> > > > http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large
> > > >
> > > > THe printing _ is because of teletypes. A teletype can't back up
other
> > > than
> > > > a carrage return. Even if it did you wouldn't be able to reliably
read
> > > > the new character printed on top of the old so they printed the
> > > underscore
> > > > for each character "backed up". On the PDP-8 you use the delete key
and
> > > > it prints the _ when configured for teletype.
> > > >
> > >
> > > In PDP 8 OS/8 using a glass vt102 terminal with a backspace key,
under
> > > standard configuration, use of backspace will generate an error even
if
> > > your command looks correct before you hit enter
> > >
> > > If you type this..
> > > .RUN RKA0;
> > >
> > > ..and then use the backspace key to correct (change semi-colon to
> > > colon)...
> > > .RUN RKA0:BASIC.SV [enter]
> > >
> > > ...OS/8 will return an OS syntax error.
> > >
> > > My original point -  you can find a way to add backspace ability, but
it
> > > was not really an option back then so you have to decide whether it
matters
> > > to you or not to bypass the historic limitation of the time.
> > >
> > > I believe that there is value to experience what it was really like
to work
> > > in this environment without modern shortcuts.  If to engineer a new
program
> > > you are required to toggle bootstraps, load a tape, enter code by
hand,
> > > punch the tape on the teletype, and so on you'll start to change your

> > > approach to programming.  The first thing you realize is that it's
best to
> > > try to write and debug as much of the code by hand before you enter
into
> > > the computer.  That's why a lot of Altair docs I have come upon have
sheets
> > > and sheets of pseudo code and hand-written listings along with the
manuals.
> > >  People did not use the computer to write and edit code like they do
today,
> > > too time consuming.  You had to be more precise in your data entry
and more
> > > organized in your approach.  No one would want to sit there for a
half hour
> > > to punch a tape, then another half hour to run the tape just to find
a
> > > single syntax error crashes the whole program.  That's why there were
a lot
> > > less people doing programming and hardware back then, this kind of
work was
> > > not for everyone.  It gives you a real appreciation for those people

> > > (before my time btw) who did all of this stuff when it was new back
then,
> > > and what motivated the likes of Woz/Jobs to make something easier to
use.
> > >
> > > Not everyone has the luxury of walking up to a computer with a
teletype. I
> > > think it would be a great service if we had an exhibit / demo for
MARCH's
> > > museum to show people what it was like to use a teletype for I/O and

> > > program storage. I would not recommend allowing the public to use it

> > > though, it'd have to be a ready-to-go demo for someone that had an
hour to
> > > witness the entire process, maybe with a little lecture to kill time

> > > between the tape loads/punches.
> > >
> > > Bill
> > >
> >
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

On Tue, Jan 08, 2013 at 09:04:47AM -0500, B. Degnan wrote:
>
> In PDP 8 OS/8 using a glass vt102 terminal with a backspace key, under
> standard configuration, use of backspace will generate an error even if
> your command looks correct before you hit enter
>
Right, you have to use the rubout/delete key to correct a mistyped
character. It will either do a backspace overwrite or print \ around
the deleted character based on the tty driver configuration/set command.

On Tue, Jan 08, 2013 at 11:34:05AM -0500, B. Degnan wrote:
> The teletype in the museum was converted to rs232.  I don't know if it was
> also upgraded to a baud faster than 110 8/n/2.  It should be possible to
> punch a tape of BASIC from the web to the modified machine's punch, and
> then load basic directly from the tape.  You'd need an absolute loader in
> ROM or on tape as well.  You could use a switch box to hop over to a glass
> terminal after the tape loads.
>
Its still 110. It was reported that the punch was jamming so if someone
wants to use is for a demo we should check it out at the next work day.
I think its only being used as a static exhibit right now.

Can we set it to 8,n,1 or it is fixed at two stop bits.  No big deal, we can
simply put something inbetween to "echo" the data between the two removing the
stop bit and maybe changing the rate from 110.  I have to investigate changing
the briel from 9600 to 110 baud.  The idea would be to get people to enjoy the
fun of toggling in the boot loader and then watching basic load.

I think we are on to something that would be fun for the public, but not risk
any real "vintage" stuff" since we would need a MARCH member to actually feed
and run the teletype (the real vintage deal).

Let's really think about this and maybe make it a group project for VCF.

Cheers,
Corey



--- In midatlanticretro@yahoogroups.com, David Gesswein  wrote:
>
> On Tue, Jan 08, 2013 at 11:34:05AM -0500, B. Degnan wrote:
> > The teletype in the museum was converted to rs232.  I don't know if it was
> > also upgraded to a baud faster than 110 8/n/2.  It should be possible to
> > punch a tape of BASIC from the web to the modified machine's punch, and
> > then load basic directly from the tape.  You'd need an absolute loader in
> > ROM or on tape as well.  You could use a switch box to hop over to a glass
> > terminal after the tape loads.
> >
> Its still 110. It was reported that the punch was jamming so if someone
> wants to use is for a demo we should check it out at the next work day.
> I think its only being used as a static exhibit right now.
>

>> but not risk any real "vintage" stuff"

I mostly agree. Definitely not letting anyone use our original copy of Altair 4K
Basic. :)

Some of the embedded FPGA work I've done really taught the value of this. 
Whenever possible I prefer to use the on chip block ram and not go external for
cost reasons.  Every time I would forget to use the minimal printf() routine I'd
run out of space for just code - let alone RAM as it linked in half the C
standard library.

I've toyed with the idea of making a few Retro-On-A-Chip computers but I think
the Briel model is a better way to go for recreating the old machines.  BGA
parts have no place in a retro machine.

--- In midatlanticretro@yahoogroups.com, Neil Cherry  wrote:
>
> On 01/08/2013 09:54 AM, corey986 wrote:
> >
> > I 100% agree. Having to "flip" switches or even type in the ocal/hex by hand
has made me a
> > better programmer. This actually came up at dinner last night (I'm at
training in Texas
> > right now) where we were talking about the "old" days and how people who
lived through
> > toggling in a boot loader on a PDP8 seemed to be more efficient in their
resource
> > utilization as programmers than the guys who started programming with Visual
Basic who
> > tend to be sloppy in memory and resource usage. It was a pretty heated
converstation
> > enhanced by wine and Fogo de Chao "Meat" high....
>
> This holds true of any restricted env such as a uC with limited resources.
>
> Of course when you've been around long enough and use larger computer
resources
> you start to think about other limited resources such as time. As an Engineer
> (EE, System Engineer, etc.) you have to look at the overall picture .
>
> But I do agree that folks who have had to live with tight limits tend to
> be better overall Engineers.
>
> --
> Linux Home Automation         Neil Cherry       ncherry@...
> http://www.linuxha.com/                         Main site
> http://linuxha.blogspot.com/                    My HA Blog
> Author of:     Linux Smart Homes For Dummies
>

The Z80 is claimed to be compatible with the 8080 but anyone who has tried to
run MITS Basic on it knows that isn't true.  The reason is that the Z-80
overloads the parity flag and uses it as an overflow flag for arithmetic
instructions.  To get the 4K basic as small as it was Bill Gates and Paul Allen
used every detail of the 8080 to the point where this minor change stops it from
working.

At this point there appears to only be vague hints about the problem online so
I'm posting this here to help anybody else out working on the issue (hopefully
Google will pick it up).  To get MITS Basic to run on a Z80 without modifying
the code you have to trap the 8080 arithmetic instructions and recompute the
parity flag.

Here is my code to do this with the z80ex emulator library:

bool FArithmeticOp(int op)
{
     if ((op & 0xF0) == 0x80)    //ADDr ADDm ADCr ADCm
         return true;
     if (op == 0xC6)             //ADI
         return true;
     if (op == 0xCE)             //ACI
         return true;
     if (((op & 0x0F) == 0x09) && ((op & 0xC0) == 0))    //DAD (all)
         return true;
     if ((op & 0xF0) == 0x90)    // SUB and SBB
         return true;
     if (op == 0xD6)     // SUI
         return true;
     if (op == 0xDE)     // SBI
         return true;
     if (op == 0x27)     // DAA
         return true;

     if ((op & 0xC0) == 0)
     {
         //Increment group
         if ((op & 0x7) == 0x4)  //INR
             return true;
         if (op == 0x3)  // INX B
             return true;
         if (op == 0x13) // INX D
             return true;
         if (op == 0x23) // INX H
             return true;
         if (op == 0x33) // INX SP
             return true;
         if ((op & 0x7) == 0x5)  // DCR
             return true;
         if (op == 0xB)  // DCX B
             return true;
         if (op == 0x1B) // DCX D
             return true;
         if (op == 0x2B) // DCX H
             return true;
         if (op == 0x3B) // DCX SP
             return true;
     }

     return false;
}

void Machine::SingleStep()
{
     int ip = z80ex_get_reg(m_pz80ctx, regPC);
     int lastop = m_mem[ip];

     z80ex_step(m_pz80ctx);

     // 8080 arithmetic HACK
     if (FArithmeticOp(lastop))
     {
         int regAFT = z80ex_get_reg(m_pz80ctx, regAF);
         if (FEvenParity(regAFT >> 8))
             regAFT = regAFT | 0x4;
         else
             regAFT = regAFT & (~0x4);
         z80ex_set_reg(m_pz80ctx, regAF, regAFT);
     }
}

I hope this helps somebody in the future.

-John

I think it will be fine with the time.    I contacted Vince Briel and he's going
to help us make the micro work with the teletype.

I think this will be fun.  We could have a sign up sheet for people to toggle in
the boot loader every 1/2 hour.  Will give them real appreciation of "instant
on".

--- In midatlanticretro@yahoogroups.com,  wrote:
>
> Work from a copy of the abs loader and orig BASIC.  It will take 30 minutes to
load, so as I have said below, this is not a quick demo.
>
>
>
> Sent from Windows Mail
>
>
> From: corey986
> Sent: ‎January‎ ‎8‎, ‎2013 ‎12‎:‎42‎ ‎PM
> To: midatlanticretro@yahoogroups.com
> Subject: [midatlanticretro] Re: Altair 8800 Web Emulator
>
>
> Can we set it to 8,n,1 or it is fixed at two stop bits.  No big deal, we can
simply put something inbetween to "echo" the data between the two removing the
stop bit and maybe changing the rate from 110.  I have to investigate changing
the briel from 9600 to 110 baud.  The idea would be to get people to enjoy the
fun of toggling in the boot loader and then watching basic load.
>
> I think we are on to something that would be fun for the public, but not risk
any real "vintage" stuff" since we would need a MARCH member to actually feed
and run the teletype (the real vintage deal).
>
> Let's really think about this and maybe make it a group project for VCF.
>
> Cheers,
> Corey
>
>
>
> --- In midatlanticretro@yahoogroups.com, David Gesswein  wrote:
> >
> > On Tue, Jan 08, 2013 at 11:34:05AM -0500, B. Degnan wrote:
> > > The teletype in the museum was converted to rs232.  I don't know if it was
> > > also upgraded to a baud faster than 110 8/n/2.  It should be possible to
> > > punch a tape of BASIC from the web to the modified machine's punch, and
> > > then load basic directly from the tape.  You'd need an absolute loader in
> > > ROM or on tape as well.  You could use a switch box to hop over to a glass
> > > terminal after the tape loads.
> > >
> > Its still 110. It was reported that the punch was jamming so if someone
> > wants to use is for a demo we should check it out at the next work day.
> > I think its only being used as a static exhibit right now.
> >
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>     http://docs.yahoo.com/info/terms/
>

On Wed, Jan 09, 2013 at 01:25:07AM -0000, corey986 wrote:
> I think it will be fine with the time.    I contacted Vince Briel and
> he's going to help us make the micro work with the teletype.
>
Does it care about the keyboard parity? I'm pretty sure I sent an email
with what it is but so far I can't find it. If it does I'll search harder.

> but not risk
> any real "vintage" stuff" since we would need a MARCH member to actually feed
> and run the teletype (the real vintage deal).
>
The mounting the tape on the reader is fiddly and I'm not sure how strong
the plastic cover is so may be better for a MARCH member for that. I would
think letting them type on the keyboard is fine.

It will be interesting to see how this goes. Long demos don't work well
during the normal show hours so its hard to really convey what usage
of these machines was really like.

... while working on my RCA Cosmac VIP.
Maybe its old news to folks here but I'll chance it:

http://www.swapmeetdave.com/PhilaMusic/Recording.htm

We have the same board in the museum... perhaps this could be
some display feature collateral for the wall nearby?

>> ... while working on my RCA Cosmac VIP.
Maybe its old news to folks here but I'll chance it:
http://www.swapmeetdave.com/PhilaMusic/Recording.htm We have the same board in
the museum... perhaps this could be some display feature collateral for the wall
nearby?

That's a good idea. I have the music CD and it's entertaining.

Fyi, Dave Ahl has been a very good friend to MARCH over the years.

>> I would think letting them type on the keyboard is fine.

Yes. We already do that.

A few times, when people were experienced or just very interested, I demo'd
writing/reading to paper tape (just a little).

But it's been a while, and I forget how to do it!

--- In midatlanticretro@yahoogroups.com, evan@... wrote:
>
> >> ... while working on my RCA Cosmac VIP.
> Maybe its old news to folks here but I'll chance it:
http://www.swapmeetdave.com/PhilaMusic/Recording.htm We have the same board in
the museum... perhaps this could be some display feature collateral for the wall
nearby?
>
> That's a good idea. I have the music CD and it's entertaining.
>
> Fyi, Dave Ahl has been a very good friend to MARCH over the years.

The LP record from 1978 is for sale right now on ebay.

It would require an old record player, but this is the right place for that!

It gets better.

The website this is on is the personal website of David Ahl
founder of Creative Computer Magazine.
Go to the home page and look up his bio.

Here's a 1984 article about himL

http://www.atarimagazines.com/creative/v10n11/66_Dave_tells_Ahl__the_hist.php

--- In midatlanticretro@yahoogroups.com, "DougCrawford"  wrote:
>
> ... while working on my RCA Cosmac VIP.
> Maybe its old news to folks here but I'll chance it:
>
> http://www.swapmeetdave.com/PhilaMusic/Recording.htm
>
> We have the same board in the museum... perhaps this could be
> some display feature collateral for the wall nearby?
>

Hi all,
   I see that the MARCH website is listing the VCF East 9.0 dates as May 18 & 19.
I just noticed that according to the ARRL website that OMARC is holding their
hamfest at the InfoAge site on the 18th.  I don't know if everyone was aware of
this and also whether this would cause any logistical problems such as parking,
resource contention, etc.  I realize that this may be common knowledge but I
wanted to make sure that everyone was aware of it just in case this fell trough
the cracks.  I was planning on going to both so I was surprised when I found out
the dates.
Regards,
Jeff Galinat - N2KWK

>> Yes it could be a problem, but let’s see what is going on.

I don't see any problems with the overlap, as explained in my last message.

>> logistic issues that will need to be ironed out, such as security between the
two events.

How do you figure?

OMARC's hamfest is a half-day event on Saturday down at the other campus. It's
not like ours where there is a ton of pre-event setup. Separate events, separate
locations, separate tickets.