Discussion:
Are all images mounted with VSDrive write-protected?
(too old to reply)
Jeff Ramsey
2017-05-28 16:19:08 UTC
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I am trying to create an HDV image on my raspberry pi that I can mount with VSDrive and copy files to. I am using the command:

mkpo -b 8000 image1.hdv HARDDRIVE

The file is created and has the correct size. I mount it with VSDrive:

vsd1 /$A2FILES/image1.hdv

I can run:

acmd -l image1.hdv and get a listing of the empty volume, the correct size and it says that it is a ProDOS disk.

I boot the A2CLOUD client disk and type 'V' to load VSDrive. I can type:

CAT,S2,D1

and I get the listing of the empty volume, and the correct volume label and size.

I launch any program that writes to disks, ADTPro, Filer, System Utilities, etc. and I try to copy files to the volume and I get an error that the volume is write-protected. I have also tried to format that volume using the same three apps and I get the same error - volume is write protected.

I went back and tried to use an 800K .po file that was installed by ADTPro - A2CLOUD.PO and I got the same results. I cannot format or write to that volume either.

Is this normal? Does VSDrive not allow writing to virtual drives or am I doing something wrong? Permissions error on the Pi? (I checked and I have a+rw set on each of these volumes.)
Jeff Ramsey
2017-05-30 04:28:41 UTC
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Post by Jeff Ramsey
mkpo -b 8000 image1.hdv HARDDRIVE
vsd1 /$A2FILES/image1.hdv
acmd -l image1.hdv and get a listing of the empty volume, the correct size and it says that it is a ProDOS disk.
CAT,S2,D1
and I get the listing of the empty volume, and the correct volume label and size.
I launch any program that writes to disks, ADTPro, Filer, System Utilities, etc. and I try to copy files to the volume and I get an error that the volume is write-protected. I have also tried to format that volume using the same three apps and I get the same error - volume is write protected.
I went back and tried to use an 800K .po file that was installed by ADTPro - A2CLOUD.PO and I got the same results. I cannot format or write to that volume either.
Is this normal? Does VSDrive not allow writing to virtual drives or am I doing something wrong? Permissions error on the Pi? (I checked and I have a+rw set on each of these volumes.)
I have read enough posts and Google search results to know that it is not always supposed to be write-protected. I just cannot figure out what is wrong with my configuration...
Kevin Dady
2017-05-30 14:53:54 UTC
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Post by Jeff Ramsey
Post by Jeff Ramsey
mkpo -b 8000 image1.hdv HARDDRIVE
vsd1 /$A2FILES/image1.hdv
acmd -l image1.hdv and get a listing of the empty volume, the correct size and it says that it is a ProDOS disk.
CAT,S2,D1
and I get the listing of the empty volume, and the correct volume label and size.
I launch any program that writes to disks, ADTPro, Filer, System Utilities, etc. and I try to copy files to the volume and I get an error that the volume is write-protected. I have also tried to format that volume using the same three apps and I get the same error - volume is write protected.
I went back and tried to use an 800K .po file that was installed by ADTPro - A2CLOUD.PO and I got the same results. I cannot format or write to that volume either.
Is this normal? Does VSDrive not allow writing to virtual drives or am I doing something wrong? Permissions error on the Pi? (I checked and I have a+rw set on each of these volumes.)
I have read enough posts and Google search results to know that it is not always supposed to be write-protected. I just cannot figure out what is wrong with my configuration...
have you tried starting the drive software with root permissions?
Jeff Ramsey
2017-05-31 18:07:38 UTC
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Post by Kevin Dady
Post by Jeff Ramsey
Post by Jeff Ramsey
mkpo -b 8000 image1.hdv HARDDRIVE
vsd1 /$A2FILES/image1.hdv
acmd -l image1.hdv and get a listing of the empty volume, the correct size and it says that it is a ProDOS disk.
CAT,S2,D1
and I get the listing of the empty volume, and the correct volume label and size.
I launch any program that writes to disks, ADTPro, Filer, System Utilities, etc. and I try to copy files to the volume and I get an error that the volume is write-protected. I have also tried to format that volume using the same three apps and I get the same error - volume is write protected.
I went back and tried to use an 800K .po file that was installed by ADTPro - A2CLOUD.PO and I got the same results. I cannot format or write to that volume either.
Is this normal? Does VSDrive not allow writing to virtual drives or am I doing something wrong? Permissions error on the Pi? (I checked and I have a+rw set on each of these volumes.)
I have read enough posts and Google search results to know that it is not always supposed to be write-protected. I just cannot figure out what is wrong with my configuration...
have you tried starting the drive software with root permissions?
Sorry, but I need to clarify. Are you asking me to mount the volume with root permissions or are you asking me to create the volume with root permissions? I have tried to 'sudo mkpo...' but when I try to mount the volume ("sudo vsd1 ...") I get an error that 'vsd1' cannot be found. My best guess is that the vsd1 and vsd2 commands are aliases in .xinitrc type file for the 'pi' user but I have not yet had a chance to check into that.
Jeff Ramsey
2017-06-02 12:53:29 UTC
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Post by Jeff Ramsey
Post by Kevin Dady
Post by Jeff Ramsey
Post by Jeff Ramsey
mkpo -b 8000 image1.hdv HARDDRIVE
vsd1 /$A2FILES/image1.hdv
acmd -l image1.hdv and get a listing of the empty volume, the correct size and it says that it is a ProDOS disk.
CAT,S2,D1
and I get the listing of the empty volume, and the correct volume label and size.
I launch any program that writes to disks, ADTPro, Filer, System Utilities, etc. and I try to copy files to the volume and I get an error that the volume is write-protected. I have also tried to format that volume using the same three apps and I get the same error - volume is write protected.
I went back and tried to use an 800K .po file that was installed by ADTPro - A2CLOUD.PO and I got the same results. I cannot format or write to that volume either.
Is this normal? Does VSDrive not allow writing to virtual drives or am I doing something wrong? Permissions error on the Pi? (I checked and I have a+rw set on each of these volumes.)
I have read enough posts and Google search results to know that it is not always supposed to be write-protected. I just cannot figure out what is wrong with my configuration...
have you tried starting the drive software with root permissions?
Sorry, but I need to clarify. Are you asking me to mount the volume with root permissions or are you asking me to create the volume with root permissions? I have tried to 'sudo mkpo...' but when I try to mount the volume ("sudo vsd1 ...") I get an error that 'vsd1' cannot be found. My best guess is that the vsd1 and vsd2 commands are aliases in .xinitrc type file for the 'pi' user but I have not yet had a chance to check into that.
I have tried to run the vsd1 command with sudo privileges and it did not help. (I ran it by running 'vsd $PATH/image.hdv' instead of 'vsd1'.) I also eliminated the possibility that my issue is with the HDV permissions on the file itself by copying the file into my users home directory and running chmod 666 on it to give rw to all users. Still being told it is a write-protected volume by System Utilities and filer and ADTPro client.

Can someone please point me towards some detailed documentation on how vsdrive works? I would like to understand how it works more thoroughly so that I don't have to keep asking all of these questions to the A2 community each step of the way. I really am a good troubleshooter, I just cannot seem to find any documentation resources on vsdrive beyond the standard client instructions and I am new to the Apple 2, having only played two games (both from MECC, BTW) on it when I was in primary school before buying one of my own in April of this year.

I don't mind putting in the time to learn how to solve this myself, I just cannot seem to find the documentation that I need to understand it at a deeper level.
David Schmidt
2017-06-02 13:17:51 UTC
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Post by Jeff Ramsey
Can someone please point me towards some detailed documentation on
how vsdrive works? I would like to understand how it works more
thoroughly so that I don't have to keep asking all of these questions
to the A2 community each step of the way. I really am a good
troubleshooter, I just cannot seem to find any documentation
resources on vsdrive beyond the standard client instructions [...]
I'm not really sure where to start. Most of the technical discussion of
VSDrive is in the code and on c.s.a2 (and where the original idea came
from... Terence J. Boldt's website,
http://apple2.boldt.ca/?page=terserialdrive). It's pretty simple,
really - it's a driver that responds to common ProDOS commands (read,
write, info) by delivering or receiving disk sblocks over the serial
port. But that doesn't seem to really be your issue. You're having
trouble with how it interacts with the Raspberry Pi and the *nix
filesystem which is kind of a whole different set of constrains that I
(as the author of VSDrive) don't really have much to do with. So I
think you're really asking for deep, technical understanding of the Pi
and it's ecosystem as it connects to the Apple II via IvanX's project
(http://ivanx.com/rasppleii/).
Post by Jeff Ramsey
[...] I am
new to the Apple 2, having only played two games (both from MECC,
BTW) on it when I was in primary school before buying one of my own
in April of this year.
Welcome - it's great you've jumped in, and I'll just add that you've
jumped directly into the deep end of the pool. More understanding will
come with time. Don't be shy about asking questions... but know that
you're not on the most common path here.
Jeff Ramsey
2017-06-02 13:32:52 UTC
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Post by David Schmidt
Post by Jeff Ramsey
Can someone please point me towards some detailed documentation on
how vsdrive works? I would like to understand how it works more
thoroughly so that I don't have to keep asking all of these questions
to the A2 community each step of the way. I really am a good
troubleshooter, I just cannot seem to find any documentation
resources on vsdrive beyond the standard client instructions [...]
I'm not really sure where to start. Most of the technical discussion of
VSDrive is in the code and on c.s.a2 (and where the original idea came
from... Terence J. Boldt's website,
http://apple2.boldt.ca/?page=terserialdrive). It's pretty simple,
really - it's a driver that responds to common ProDOS commands (read,
write, info) by delivering or receiving disk sblocks over the serial
port. But that doesn't seem to really be your issue. You're having
trouble with how it interacts with the Raspberry Pi and the *nix
filesystem which is kind of a whole different set of constrains that I
(as the author of VSDrive) don't really have much to do with. So I
think you're really asking for deep, technical understanding of the Pi
and it's ecosystem as it connects to the Apple II via IvanX's project
(http://ivanx.com/rasppleii/).
I first ran across the whole RASPPLE II project on Ivans site. I think if a website can be 'worn out' it would have traces of my mouse all over it by now. Even before I purchased the Apple IIe, I was reading and rereading every detail on this site.

As long as I can confirm that my issue really is in Linux on the Pi then I will continue to focus there and that will be ok. I was just trying to be efficient and not spend my time looking there so much if what I needed to do was obtain an updated client or change a dip switch setting on my SSC so that the Apple II would see the vsdrive as writeable, etc.

I have been talking with Joseph Carter on Facebook, who has apparently taken over the development of RASPPLE II from Ivan at this time. I think he is working with you on the A2Pi card revisions? Anyhow, I'll continue to work with him on getting the Pi to allow me to write to the images. Thanks for the explanation on how VSDrive works.
Post by David Schmidt
Post by Jeff Ramsey
[...] I am
new to the Apple 2, having only played two games (both from MECC,
BTW) on it when I was in primary school before buying one of my own
in April of this year.
Welcome - it's great you've jumped in, and I'll just add that you've
jumped directly into the deep end of the pool. More understanding will
come with time. Don't be shy about asking questions... but know that
you're not on the most common path here.
Thanks for the welcome. I understand all about the deep end. Unfortunately I have always lacked that "take is slow, walk before you run" thing when it comes to compu^H^H^H^H^H life.
James Davis
2017-06-03 01:26:41 UTC
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Hi Jeff,

Reading the webpage Schmidtd gave, http://apple2.boldt.ca/?page=terserialdrive, makes me think such an Apple IIgs virtual drive is too dangerous to trust good data with.

Have you downloaded this?

ftp://public.asimov.net/pub/apple_II/utility/Apple2VirtualDrive.zip

Yours truly,

James Davis
David Schmidt
2017-06-03 06:01:08 UTC
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Post by James Davis
Hi Jeff,
Reading the webpage Schmidtd gave, http://apple2.boldt.ca/?page=terserialdrive, makes me think such an Apple IIgs virtual drive is too dangerous to trust good data with.
Have you downloaded this?
ftp://public.asimov.net/pub/apple_II/utility/Apple2VirtualDrive.zip
Sure. That's where the ADTPro version grew from. There's a little bit
more safety built in now, and it does other silly things like sets the
timestamps on files. But otherwise, remember... serial links are pretty
shaky things to begin with. I wouldn't be running a nuclear reactor
that depended on data integrity offered by a serial drive.
John Brooks
2017-06-06 19:50:43 UTC
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Post by David Schmidt
Post by James Davis
Hi Jeff,
Reading the webpage Schmidtd gave, http://apple2.boldt.ca/?page=terserialdrive, makes me think such an Apple IIgs virtual drive is too dangerous to trust good data with.
Have you downloaded this?
ftp://public.asimov.net/pub/apple_II/utility/Apple2VirtualDrive.zip
Sure. That's where the ADTPro version grew from. There's a little bit
more safety built in now, and it does other silly things like sets the
timestamps on files. But otherwise, remember... serial links are pretty
shaky things to begin with. I wouldn't be running a nuclear reactor
that depended on data integrity offered by a serial drive.
FWIW: On my IIGS I use standard serial cable-to-USB (PL2303 chipset) and homebrew drivers for Mac OS X & ProDOS to mount a 32MB virtual serial drive at 230K baud (about 2x faster than physical 5.25 drives). It's been rock solid for almost 2 years.

-JB
@JBrooksBSI
Hugh Hood
2017-06-07 02:13:01 UTC
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Post by John Brooks
FWIW: On my IIGS I use standard serial cable-to-USB (PL2303 chipset) and homebrew drivers for Mac OS X & ProDOS to mount a 32MB virtual serial drive at 230K baud (about 2x faster than physical 5.25 drives). It's been rock solid for almost 2 years.
-JB
@JBrooksBSI
John,

That's quite a tease you threw out there. Is this a project you plan to
release at a future date?

I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?

The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.





Hugh Hood
John Brooks
2017-06-08 13:44:04 UTC
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Post by Hugh Hood
Post by John Brooks
FWIW: On my IIGS I use standard serial cable-to-USB (PL2303 chipset) and homebrew drivers for Mac OS X & ProDOS to mount a 32MB virtual serial drive at 230K baud (about 2x faster than physical 5.25 drives). It's been rock solid for almost 2 years.
-JB
@JBrooksBSI
John,
That's quite a tease you threw out there. Is this a project you plan to
release at a future date?
I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?
The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.
Hugh Hood
That's quite a tease you threw out there. Is this a project you plan to
release at a future date?

Yes, I'll be talking about it as part of the "Improvements to ProDOS" presentation at KFest 2017.
Post by Hugh Hood
I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?

If you already have a Z8530 driver, it should not be hard to modify it for 230k baud. The GS 8530 clock is 2x faster than in the SSC (3.6864 MHz vs 1.8 MHz), so the 16x divider results in 230k baud. The baud-rate generator is not stable at high speeds, so disable it and just use the input clock/16.

ProDOS drivers are a bit tricky as the GS serial firmware will fight custom drivers and pressing Reset will re-init the Z8530 configuration.

Oh, and don't use super-long serial cables as RS-232 does not have the noise immunity of RS-422 differential cables.
Post by Hugh Hood
The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.
Yes, 230K baud over long cables requires RS-422 differential signaling. Also, Appletalk's self-clocked NRZI encoding and ability for multiple computers to share one connection are incompatible with RS-232.

But IMO, for retro-Apple II use, standard-length RS-232 cables directly connecting two computers is the way to go and both more convenient and more compatible than Appletalk.

-JB
@JBrooksBSI
Hugh Hood
2017-06-08 19:16:24 UTC
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John,

Thanks for your explanation, and I look forward to your hearing about your
'Improvements to ProDOS' from Kfest next month.

I'm going to modify my 115,200 baud ProTERM driver (which disables the baud
rate generator and uses a 32x divider) and change it to use a 16x divider.

I'll then see if I can do quicker Zmodem transfers with it.

FWIW, I know from my 115,200 baud terminal use that the ProTERM _display_
drops some characters at that rate, so I'm not expecting that to change (and
imagine that it will drop _more_), but I'd like to see if I can 'upshift' to
230K baud for my Zmodem transfers.

115,200 baud Zmodem transfers work great with ProTERM.

Actually, though, your 230K baud ProDOS serial driver sounds even better.
:-)






Hugh Hood
Post by John Brooks
Post by Hugh Hood
That's quite a tease you threw out there. Is this a project you plan to
release at a future date?
Yes, I'll be talking about it as part of the "Improvements to ProDOS"
presentation at KFest 2017.
Post by Hugh Hood
I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?
If you already have a Z8530 driver, it should not be hard to modify it for
230k baud. The GS 8530 clock is 2x faster than in the SSC (3.6864 MHz vs 1.8
MHz), so the 16x divider results in 230k baud. The baud-rate generator is not
stable at high speeds, so disable it and just use the input clock/16.
ProDOS drivers are a bit tricky as the GS serial firmware will fight custom
drivers and pressing Reset will re-init the Z8530 configuration.
Oh, and don't use super-long serial cables as RS-232 does not have the noise
immunity of RS-422 differential cables.
Post by Hugh Hood
The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.
Yes, 230K baud over long cables requires RS-422 differential signaling. Also,
Appletalk's self-clocked NRZI encoding and ability for multiple computers to
share one connection are incompatible with RS-232.
But IMO, for retro-Apple II use, standard-length RS-232 cables directly
connecting two computers is the way to go and both more convenient and more
compatible than Appletalk.
-JB
@JBrooksBSI
David Schmidt
2017-06-08 19:44:24 UTC
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Post by Hugh Hood
[...]
115,200 baud Zmodem transfers work great with ProTERM.
Actually, though, your 230K baud ProDOS serial driver sounds even better.
:-)
With the right serial drivers on the host side (it's got to be able to
twiddle the bits at that rate through, say, your USB adapter) it's
doable with a GS. I never bothered implementing the rate in the ADTPro
comm subsystem because it would be specific to the GS and the Zilog
chip, and I like to be inclusive. :-)

@JB - does it work with a GS running at "slow" speed? I'd suspect not.
John Brooks
2017-06-09 00:06:27 UTC
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Post by David Schmidt
Post by Hugh Hood
[...]
115,200 baud Zmodem transfers work great with ProTERM.
Actually, though, your 230K baud ProDOS serial driver sounds even better.
:-)
With the right serial drivers on the host side (it's got to be able to
twiddle the bits at that rate through, say, your USB adapter) it's
doable with a GS. I never bothered implementing the rate in the ADTPro
comm subsystem because it would be specific to the GS and the Zilog
chip, and I like to be inclusive. :-)
@JB - does it work with a GS running at "slow" speed? I'd suspect not.
Kind of. Since all transfers are invoked by the ProDOS driver as 'master', the driver saves the IIGS speed on entry and forces fast speed for the duration of the block transfer, then restores the GS speed setting on exit.

-JB
@JBrooksBSI
James Davis
2017-06-09 02:27:34 UTC
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Post by Hugh Hood
John,
Thanks for your explanation, and I look forward to your hearing about your
'Improvements to ProDOS' from Kfest next month.
I'm going to modify my 115,200 baud ProTERM driver (which disables the baud
rate generator and uses a 32x divider) and change it to use a 16x divider.
I'll then see if I can do quicker Zmodem transfers with it.
FWIW, I know from my 115,200 baud terminal use that the ProTERM _display_
drops some characters at that rate, so I'm not expecting that to change (and
imagine that it will drop _more_), but I'd like to see if I can 'upshift' to
230K baud for my Zmodem transfers.
115,200 baud Zmodem transfers work great with ProTERM.
Actually, though, your 230K baud ProDOS serial driver sounds even better.
:-)
Hugh Hood
in article 624b9d4e-64e3-477f-a7f0-cc11b159aaa0 at googlegroups.com, John
Post by John Brooks
Post by Hugh Hood
That's quite a tease you threw out there. Is this a project you plan to
release at a future date?
Yes, I'll be talking about it as part of the "Improvements to ProDOS"
presentation at KFest 2017.
Post by Hugh Hood
I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?
If you already have a Z8530 driver, it should not be hard to modify it for
230k baud. The GS 8530 clock is 2x faster than in the SSC (3.6864 MHz vs 1.8
MHz), so the 16x divider results in 230k baud. The baud-rate generator is not
stable at high speeds, so disable it and just use the input clock/16.
ProDOS drivers are a bit tricky as the GS serial firmware will fight custom
drivers and pressing Reset will re-init the Z8530 configuration.
Oh, and don't use super-long serial cables as RS-232 does not have the noise
immunity of RS-422 differential cables.
Post by Hugh Hood
The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.
Yes, 230K baud over long cables requires RS-422 differential signaling. Also,
Appletalk's self-clocked NRZI encoding and ability for multiple computers to
share one connection are incompatible with RS-232.
But IMO, for retro-Apple II use, standard-length RS-232 cables directly
connecting two computers is the way to go and both more convenient and more
compatible than Appletalk.
-JB
@JBrooksBSI
An excerpt from:

"A 57600 Baud Interface" by Don Lancaster - ASK THE GURU - April, 1989

Just how fast can an unassisted IIe or IIgs output serial data? The surprising answer to this is 14 Megabaud. Yeah. Mega, not kilo. You do this by putting your data on the super HIRES screen and using the video connector for the serial output.
James Davis
2017-06-09 02:29:47 UTC
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An excerpt from:

"A 57600 Baud Interface" by Don Lancaster - ASK THE GURU - April, 1989

Just how fast can an unassisted IIe or IIgs output serial data? The surprising answer to this is 14 Megabaud. Yeah. Mega, not kilo. You do this by putting your data on the super HIRES screen and using the video connector for the serial output.
Hugh Hood
2017-07-06 02:24:12 UTC
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RE: ProTERM 3.1 230,400 baud IIGS SCC Driver
----------------------------------------------

OK, based on John Brooks' experience with his 230K baud ProDOS serial
driver, I modified my patched ProTERM 3.1 IIGS SCC driver for 230,400
baud and son-of-a-gun, it worked. Well, sort of.

Zmodem _Sends_ worked swiftly and error-free.

For example, a 140K .dsk image file transferred from the IIGS at a
reported rate of 15,928 CPS (9330K/minute).

Zmodem _Receives_ did not work at all. They still work well at 115,200
baud, though.

Obviously, the video screen loses characters at 230K baud, so it's not
suitable for Terminal work, at least not on a mere Zip GSX 7/32 machine
like mine is. Maybe Plamen will have a rabbit up his sleeve for the IIGS
before too long, and I can try it again with that.

Thanks again, John, for even suggesting that this was possible, and I'm
forward to your ProDOS serial driver implementation to be introduced
later this month.





Hugh Hood
Post by Hugh Hood
John,
Thanks for your explanation, and I look forward to your hearing about your
'Improvements to ProDOS' from Kfest next month.
I'm going to modify my 115,200 baud ProTERM driver (which disables the baud
rate generator and uses a 32x divider) and change it to use a 16x divider.
I'll then see if I can do quicker Zmodem transfers with it.
FWIW, I know from my 115,200 baud terminal use that the ProTERM _display_
drops some characters at that rate, so I'm not expecting that to change (and
imagine that it will drop _more_), but I'd like to see if I can 'upshift' to
230K baud for my Zmodem transfers.
115,200 baud Zmodem transfers work great with ProTERM.
Actually, though, your 230K baud ProDOS serial driver sounds even better.
:-)
Hugh Hood
Post by John Brooks
Post by Hugh Hood
That's quite a tease you threw out there. Is this a project you plan to
release at a future date?
Yes, I'll be talking about it as part of the "Improvements to ProDOS"
presentation at KFest 2017.
Post by Hugh Hood
I've programmed the Zilog SCC to do 115,200 on an accelerated GS for
Zmodem stuff, but how in the world are you able to get reliable 230K comm?
If you already have a Z8530 driver, it should not be hard to modify it for
230k baud. The GS 8530 clock is 2x faster than in the SSC (3.6864 MHz vs 1.8
MHz), so the 16x divider results in 230k baud. The baud-rate generator is not
stable at high speeds, so disable it and just use the input clock/16.
ProDOS drivers are a bit tricky as the GS serial firmware will fight custom
drivers and pressing Reset will re-init the Z8530 configuration.
Oh, and don't use super-long serial cables as RS-232 does not have the noise
immunity of RS-422 differential cables.
Post by Hugh Hood
The accepted wisdom was always that only AppleTalk could use that speed,
and yet you've seem to have kicked down another wall. Impressive.
Yes, 230K baud over long cables requires RS-422 differential signaling. Also,
Appletalk's self-clocked NRZI encoding and ability for multiple computers to
share one connection are incompatible with RS-232.
But IMO, for retro-Apple II use, standard-length RS-232 cables directly
connecting two computers is the way to go and both more convenient and more
compatible than Appletalk.
-JB
@JBrooksBSI
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