Pdp-8 focal @ Kennett Classic
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
On 7/6/23 21:45, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc.
Niiiiice!! -Dave -- Dave McGuire, AK4HZ New Kensington, PA
Yah, when you declare publicly then you're committed to actually do it. Setting up terminal strip on the Teletype and all that. On Thu, Jul 6, 2023, 9:46 PM Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On 7/6/23 21:45, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc.
Niiiiice!!
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
Excellent. :-) -Dave On 7/6/23 21:52, Bill Degnan via vcf-midatlantic wrote:
Yah, when you declare publicly then you're committed to actually do it. Setting up terminal strip on the Teletype and all that.
On Thu, Jul 6, 2023, 9:46 PM Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On 7/6/23 21:45, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc.
Niiiiice!!
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem. Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog. On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
Dave Inhave an actual tape with loader prepared. I get what're saying about the baud. I don't have a run relay. I guess we'll see On Thu, Jul 6, 2023, 10:16 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem.
Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog.
On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
If you do run into the overrun problem loading a FOCAL source file just take the reader out of run every 1/2 time it took to overrun until PDP-8 stops sending and it will be fine. A lot of the FOCAL program around are too large for 4k. I have a Lunar Landar that works in 4k if you haven't already found something to load under FOCAL. Assuming this was part of your plan or were you just loading FOCAL binary? On Thu, Jul 06, 2023 at 10:33:37PM -0400, Bill Degnan via vcf-midatlantic wrote:
Dave Inhave an actual tape with loader prepared. I get what're saying about the baud. I don't have a run relay. I guess we'll see
On Thu, Jul 6, 2023, 10:16 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem.
Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog.
On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
Basically yrs, just load the binary. That's pretty ambitious for one day. I really just want to get started, measure voltages, etc. I was given a focal tape with a loader from,.believe it ornot a former owner of the pdp 8 I have in the museum. On Thu, Jul 6, 2023, 10:53 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
If you do run into the overrun problem loading a FOCAL source file just take the reader out of run every 1/2 time it took to overrun until PDP-8 stops sending and it will be fine.
A lot of the FOCAL program around are too large for 4k. I have a Lunar Landar that works in 4k if you haven't already found something to load under FOCAL. Assuming this was part of your plan or were you just loading FOCAL binary?
On Thu, Jul 06, 2023 at 10:33:37PM -0400, Bill Degnan via vcf-midatlantic wrote:
Dave Inhave an actual tape with loader prepared. I get what're saying about the baud. I don't have a run relay. I guess we'll see
On Thu, Jul 6, 2023, 10:16 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem.
Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog.
On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
Just set the sender to 1.5 or 2 stop bits. That will cover for minor speed differences. TTYs sent 1.5 stop bits for that reason. On 7/6/2023 10:15 PM, David Gesswein via vcf-midatlantic wrote:
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem.
Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog.
On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
-- DuaneCraps sdɐɹɔ ǝuɐnp
I will be using an actual papertape/teletype On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
Just set the sender to 1.5 or 2 stop bits. That will cover for minor speed differences. TTYs sent 1.5 stop bits for that reason.
On 7/6/2023 10:15 PM, David Gesswein via vcf-midatlantic wrote:
Note if your loading a FOCAL program if whatever is sending baudrate is faster than the PDP-8 transmit baud rate the loading will fail after a while with buffer overrun. I've adjusted the pot on the TTY clock card to make it load from a teletype. I'm talking if your using a PC that transmits exactly 110 baud and the PDP-8 actually transmits at 108 baud you have problems. Loading the FOCAL tape itself doesn't have this problem.
Note that some versions of the FOCAL tape have two sections so without reader run if you don't hit continue quick enough after the first halt you will not load the initial dialog.
On Thu, Jul 06, 2023 at 09:45:15PM -0400, Bill Degnan via vcf-midatlantic wrote:
Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
-- DuaneCraps sdɐɹɔ ǝuɐnp
On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
Just set the sender to 1.5 or 2 stop bits. That will cover for minor speed differences. TTYs sent 1.5 stop bits for that reason.
Model 15 and friends (5-level "Baudot") used 1.5 stop bits. ASR33 used 2. Definitely need the stop bits because the mechanical devices have required recycle times to get rotating things back around to the top. But there's also pacing problems between chars. The reason the DEC LT33 adds the Reader Run Relay to the standard ASR33 is because if the TTY is sending chars back to back but the PDP-8 is off processing previous chars, it's going to fail to keep up and you'll lose chars. It happens with the RIM and BIN loaders but it's especially pronounced when reading programs into interpreted languages like FOCAL and BASIC. At the last couple of VCFs, I had to put huge, huge delays (many milliseconds) at the end of each line when sending FOCAL and BASIC programs to a real PDP-8/a running BASIC or FOCAL. Also had small delays between chars, but the EOL pauses when the interpreters went off to process the entire line were extensive. I wish you luck with reading in FOCAL on an ASR33 without a Reader Run Relay. It might be successful but I wouldn't be surprised if you just can't. You could probably have some luck reading in a tape image from a modern machine that dribbles the chars into the PDP-8. -ethan -ethan -ethan
Agreed. I was able to get the TTY current loop secure, which is a good first step. I have a reader relay I can install. I have some no name ones too. But it's going to be a while, RAM is an issue first. Dave Gesswein pointed out a few things I should check/do next. I can load simple programs but bits they are a droppin. On Sat, Jul 8, 2023, 3:27 PM Ethan Dicks via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
Just set the sender to 1.5 or 2 stop bits. That will cover for minor speed differences. TTYs sent 1.5 stop bits for that reason.
Model 15 and friends (5-level "Baudot") used 1.5 stop bits. ASR33 used 2.
Definitely need the stop bits because the mechanical devices have required recycle times to get rotating things back around to the top.
But there's also pacing problems between chars. The reason the DEC LT33 adds the Reader Run Relay to the standard ASR33 is because if the TTY is sending chars back to back but the PDP-8 is off processing previous chars, it's going to fail to keep up and you'll lose chars. It happens with the RIM and BIN loaders but it's especially pronounced when reading programs into interpreted languages like FOCAL and BASIC.
At the last couple of VCFs, I had to put huge, huge delays (many milliseconds) at the end of each line when sending FOCAL and BASIC programs to a real PDP-8/a running BASIC or FOCAL. Also had small delays between chars, but the EOL pauses when the interpreters went off to process the entire line were extensive.
I wish you luck with reading in FOCAL on an ASR33 without a Reader Run Relay. It might be successful but I wouldn't be surprised if you just can't. You could probably have some luck reading in a tape image from a modern machine that dribbles the chars into the PDP-8.
-ethan
-ethan
-ethan
On Sat, Jul 08, 2023 at 03:26:57PM -0400, Ethan Dicks via vcf-midatlantic wrote:
On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
But there's also pacing problems between chars. The reason the DEC LT33 adds the Reader Run Relay to the standard ASR33 is because if the TTY is sending chars back to back but the PDP-8 is off processing previous chars, it's going to fail to keep up and you'll lose chars. It happens with the RIM and BIN loaders
I don't see how this can be an issue with standalone RIM and only an issue with BIN if you have two sections on the tape so 8 halts between. I've found the code path is short enough that any reasonable baud rate character time is longer than the time for 8 to be ready for next character. If your reading tapes under OS/8 or other OS then you do need reader run. For early 8's without buffered serial port reasonable is lower since you have less time till next character will corrupt current. I haven't done test/analysis to determine limit but think its worked for me at 9600 without reader run. At 110 baud 1 bit time is 3000 3us instructions.
but it's especially pronounced when reading programs into interpreted languages like FOCAL and BASIC.
The early FOCAL's I've been playing with use interrupts for the serial I/O reading into a buffer. The code isn't smart enough to turn off receiving to prevent overrun so the reader run doesn't help case I was discussing with the slight mismatch of baud rates. Code is hard to follow but their likely is an IOF in path of adding new lines so reader run probably helps their. Don't know if later FOCAL's improved this. For loading from PC I have a program that checks the echo back to prevent overrun at high baud rates. I haven't played enough with BASIC reading from console to comment.
Do you have a source online for PDP-8 toggle in test programs, such as echo characters to/from the TTY and PDP-8? THe PDP-8e versions are different. I can probably figure some of it out, like I did with the chase the lights, but I am always up to make things easier. I have loaded and run PDP 11 BASIC without a reader run relay. The FOCAL tape I have came from the former owner of the machine. First though, I need to get the RAM to behave solidly, so I need to check the diodes of the flip chips and measure what's happening to the best of my ability. I can load simple programs like the chase the lights but I could not load in the papertape loader successfully, ~20 instructions. On Sat, Jul 8, 2023 at 8:35 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On Sat, Jul 08, 2023 at 03:26:57PM -0400, Ethan Dicks via vcf-midatlantic wrote:
On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
But there's also pacing problems between chars. The reason the DEC LT33 adds the Reader Run Relay to the standard ASR33 is because if the TTY is sending chars back to back but the PDP-8 is off processing previous chars, it's going to fail to keep up and you'll lose chars. It happens with the RIM and BIN loaders
I don't see how this can be an issue with standalone RIM and only an issue with BIN if you have two sections on the tape so 8 halts between. I've found the code path is short enough that any reasonable baud rate character time is longer than the time for 8 to be ready for next character. If your reading tapes under OS/8 or other OS then you do need reader run. For early 8's without buffered serial port reasonable is lower since you have less time till next character will corrupt current. I haven't done test/analysis to determine limit but think its worked for me at 9600 without reader run. At 110 baud 1 bit time is 3000 3us instructions.
but it's especially pronounced when reading programs into interpreted languages like FOCAL and BASIC.
The early FOCAL's I've been playing with use interrupts for the serial I/O reading into a buffer. The code isn't smart enough to turn off receiving to prevent overrun so the reader run doesn't help case I was discussing with the slight mismatch of baud rates. Code is hard to follow but their likely is an IOF in path of adding new lines so reader run probably helps their. Don't know if later FOCAL's improved this. For loading from PC I have a program that checks the echo back to prevent overrun at high baud rates.
I haven't played enough with BASIC reading from console to comment.
On Sat, Jul 08, 2023 at 09:27:44PM -0400, Bill Degnan via vcf-midatlantic wrote:
Do you have a source online for PDP-8 toggle in test programs, such as echo characters to/from the TTY and PDP-8? THe PDP-8e versions are different. I can probably figure some of it out, like I did with the chase the lights, but I am always up to make things easier.
I've used print and echo TTY tests on straight 8. BSW is not valid for straight 8 so tests will give different results after BSW. IAC with rotate are also invalid but didn't see any in quick look. Don't remember seeing straight-8 specific toggle in tests. http://www.pdp8online.com/pdp8cgi/query_docs/tifftopdf.pl/pdp8docs/toggle_in...
I have loaded and run PDP 11 BASIC without a reader run relay. The FOCAL tape I have came from the former owner of the machine.
First though, I need to get the RAM to behave solidly, so I need to check the diodes of the flip chips and measure what's happening to the best of my ability. I can load simple programs like the chase the lights but I could not load in the papertape loader successfully, ~20 instructions.
On Sat, Jul 8, 2023 at 8:35 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On Sat, Jul 08, 2023 at 03:26:57PM -0400, Ethan Dicks via vcf-midatlantic wrote:
On Fri, Jul 7, 2023 at 10:39 AM Duane Craps via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
But there's also pacing problems between chars. The reason the DEC LT33 adds the Reader Run Relay to the standard ASR33 is because if the TTY is sending chars back to back but the PDP-8 is off processing previous chars, it's going to fail to keep up and you'll lose chars. It happens with the RIM and BIN loaders
I don't see how this can be an issue with standalone RIM and only an issue with BIN if you have two sections on the tape so 8 halts between. I've found the code path is short enough that any reasonable baud rate character time is longer than the time for 8 to be ready for next character. If your reading tapes under OS/8 or other OS then you do need reader run. For early 8's without buffered serial port reasonable is lower since you have less time till next character will corrupt current. I haven't done test/analysis to determine limit but think its worked for me at 9600 without reader run. At 110 baud 1 bit time is 3000 3us instructions.
but it's especially pronounced when reading programs into interpreted languages like FOCAL and BASIC.
The early FOCAL's I've been playing with use interrupts for the serial I/O reading into a buffer. The code isn't smart enough to turn off receiving to prevent overrun so the reader run doesn't help case I was discussing with the slight mismatch of baud rates. Code is hard to follow but their likely is an IOF in path of adding new lines so reader run probably helps their. Don't know if later FOCAL's improved this. For loading from PC I have a program that checks the echo back to prevent overrun at high baud rates.
I haven't played enough with BASIC reading from console to comment.
On Sat, Jul 8, 2023 at 10:19 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On Sat, Jul 08, 2023 at 09:27:44PM -0400, Bill Degnan via vcf-midatlantic wrote:
Do you have a source online for PDP-8 toggle in test programs, such as echo characters to/from the TTY and PDP-8? THe PDP-8e versions are different. I can probably figure some of it out, like I did with the chase the lights, but I am always up to make things easier.
I've used print and echo TTY tests on straight 8.
BSW is not valid for straight 8 so tests will give different results after BSW. IAC with rotate are also invalid but didn't see any in quick look. Don't remember seeing straight-8 specific toggle in tests.
http://www.pdp8online.com/pdp8cgi/query_docs/tifftopdf.pl/pdp8docs/toggle_in...
Thank you for checking. Here is one I made from the assembly code found on wikiwand: 0010 / Set current assembly origin to address 10 STPTR, 7776 / An auto-increment register (one of eight at 10-17) 0200 / Set current assembly origin to program text area HELLO, 7000 / CLA CLL 7016 / TAD I Z STPTR 7400 / SNA 7400 / HLT 7500 / TLS 7540 / TSF 5000 / JMP .-1 5200 / JMP HELLO STRNG, 0310 / H 0345 / e 0354 / l 0354 / l 0357 / o 0254 / , 0240 / (space) 0367 / w 0357 / o 0362 / r 0354 / l 0344 / d 0241 / ! 0000 / End of string $HELLO 0000 / Default terminator
Very cool! Here's a little FOCAL program that I show as part of a demonstration to our freshmen every spring. It finds the 3-digit numbers that are equal to the sum of the cubes of the digits. C-FOCAL,1969 01.10 FOR I=1,9; DO 1.20 01.11 QUIT 01.20 FOR J=0,9; DO 1.30 01.30 FOR K=0,9; DO 2 02.01 SET N1=I*I*I+J*J*J+K*K*K 02.02 SET N2=I*100+J*10+K 02.03 IF (N1-N2) 2.13,2.10,2.13 02.10 TYPE N2,! 02.13 RETURN * Following up on David's message, I too have seen FOCAL not be able to take code faster than TTY speed. As for the multiple sections, I've had good luck with the version on the tape DEC-08-AJAE-PB. It seems to load fine in a single pass. (Though I have to admit to faking the paper tape.) BLS On Friday, July 7, 2023 at 01:45:34 AM UTC, Bill Degnan via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote: Saturday at the museum we're going to try to load FOCAL from papertape into the PDP-8 system. 12 noon to ? All are welcome. Also going to document system in detail, measure voltages, etc. Kennettclassic.com Bill
participants (6)
-
Bill Degnan -
Brian L. Stuart -
Dave McGuire -
David Gesswein -
Duane Craps -
Ethan Dicks