Another smaller problem.

[ctalmeida]

Hello again,

Does anyone uses a computer to record the programs at 300 baud?
I think should work as any tape recorder.

The OSI 600 servicing data manual tell to do a short on pin 10 and 9 of J2 and then check the timing of the pulse on the pin 5 of U69.
It must be from 500us to 640us.
I never get that, most I get is 480us.

Is anyone able to give me a hint what component can be the problem, I am thinking should be something on the C13, R54, R55 or R56.
I can understand digital logic but when gets to capacitors/resistors I am bad.

The recording kind of works but for sure this difference I think is a problem.

Does anyone have a wav, wma or any sound file that I can have as a standard here?

Thank you for any help

Carlos

[Mark]

Hi Carlos,

It seems unusual for those components to fail, but I guess it's possible. Are the values the same as the schematic? Perhaps someone modified the filter to work at a higher baudrate/frequency? If you send in a 1200 or 2400Hz signal, what do you see at the output of U66 pin 6 on your scope? What logic level is at pin 5 U63 for each frequency?

If you'd like a sample WAV, try John Conway's Life program archive. It's on my games page. It contains WAV files for C1P, and C2P, generated by OSIKCS.

Signal levels need to be rather high for cassette playback (I always cranked it to 90% or so), without any bass/treble enhancements.
Besides jumpering, another option is to send the cassette output back to the input using the cassette recorder as an amplifier to get a real-world input (some can do that by using Mic & Speaker jacks at the same time, some not) .
Use the attached small program which continuously sends printable ASCII and shows what was received on screen, then adjust the filter pot R57 until you get uncorrupted text. You can enter the HEX data in the ROM monitor at $0280 (ignore the spaces and newlines). This program is designed for the C1/Superboard.

I'll attach these bits in a zip file below.

Good Luck!
-Mark

Reset C1P, press 'C' <return><return>to cold start. Reset again, press 'M' and enter the following data. At the last G C1P should continuously send ASCII 32 to 126 characters, and display what ever is received on screen. You can restart this program by starting ROM monitor and entering .0280G (it should survive RESETS and coldstarts). Note: OSI receiving ^O stops screen printing.

Code: Select all

.0280/
A9 03 8D 00 F0 A9 15 8D 00 F0 A2 20 AD 00 F0 4A 
90 06 AD 01 F0 20 2D BF AD 00 F0 4A 4A 90 ED 8A 
8D 01 F0 E8 E0 7F 90 E4 B0 E0 
.0280G

Code: Select all

C1ACIA = $F000
	*=$0280
	.EXE * ;emit A65 load address
	LDA #$03
	STA C1ACIA	;reset ACIA
	LDA #$15	;= 8N1 /16
	STA C1ACIA	;set 8N1
	LDX #$20	; 1st character to send
	
LOOP	
	LDA C1ACIA	;test for received data
	LSR A    
	BCC NEXT 	;data received?
	LDA C1ACIA+1
	JSR $BF2D	;write to screen
NEXT
	LDA C1ACIA 	;is sending queue empty?
	LSR A     
	LSR A     
	BCC LOOP	;nope
	TXA
	STA C1ACIA+1 ;write character to port
	INX
	CPX #$7f	;next character value
	BCC LOOP
	BCS LOOP-2	;start over with 1st character

[ctalmeida]

Hi Mark,

Thank you very much.

I will check what you said, try to load some of the wav files tomorrow and come back to you.

Thank you

Carlos

[ctalmeida]

Hi Mark,

Here what I got.
Both boards read with no problems your Night Rider wav file game, both load and run.
Then with the game loaded I saved in other file and try to reload the new saved file, is all garbage.
Looks like the reading part on both boards is fine the output is the problem.

I attached a picture of the pin 6 U66 and one of the pin 5 U53.

When I hear and compare the actual wav file I recorded on the computer and the one I got from you, mine volume is for sure lower and I fill like the pitch is a but lower on mine. I did set my computer mic to +30db but that did not help.

Does that gives any clue?

I am using the mic output of the 600 board, should I try to use the aux?

Thanks for your help

Carlos

[Mark]

If loading works fine, then the problem is most likely just signal levels on the OSI output not driving your recording device. The cassette output from the OSI was intended for the external, non-powered microphone input on a cassette recorder. It has a very low amplitude. If you are plugging that into something that expects a powered mic input, or if the mic input is providing power, it may cause problems. I've never plugged it into anything other than a cassette recorder or an LM386 based amplifier. (If recording on a digital device, do not use a lossy compression like MP3.)

So yes, try using OSI J2-9 with AUX input for a higher signal level. (Maybe filter the output through a 10uf capacitor or so to remove the DC bias if that is a problem.)

You know once you coldboot the OSI, you can type 'SAVE' and everything you type on the keyboard (or actually anything printed to the screen) will be echoed to the serial port cassette output. You can enter the LOAD command and play that back.

You are correct, the software generated WAV files from OSIKCS sound higher and are in fact 2% faster than standard in order to have a highly compressible digital file. The 2400 and 1200Hz cycles generated in the WAV file do not evenly divide into the standard sample rate of 22050 samples/sec. They are actually 21600 samples/sec played at 22050 making them just a little bit higher in frequency, 2450Hz and ~305bps. This doesn't affect the loading into OSI, but decreases WAV file sizes in archives by 90x+!

-Mark

[ctalmeida]

Hi Mark,

After all tests here is what the problem is, .wma files
I tried all, nothing worked then I figure how to use the windows sound recorder to record as .wav file format.

When I record as .wav all works, using pin 7 or pin 9 or J2, both work.

Good to know do not use .wma file format, .wav works.

Never thought that would made a difference like that.

Thank you again for your help, love the games on your page.

Carlos

[Mark]

Hi Carlos,
I'm glad you figured it out!
As you've seen, lossy compression is a problem for this type of data.

Although you had problems with regular WMA, WMA is in fact a wrapper for four different codecs. There is a lossless WMA codec which would probably work fine. As it happens, WAV is also a container format which usually contains uncompressed PCM encoded audio, but can also contain lossy compressed audio which would cause problems, so it's important to select the right codec when recording. The more you know...

From my experience, for WAV PCM recording of OSI output you can get by with 22050 samples/sec 8bit mono. You can record at higher sample rates and bit depth, but it doesn't improve the recording. It does increase the file size though! Record at a level that does not clip, but uses most of the range available. I've used cross platform Audacity and Windows sound recorder with good success. Audacity is useful when trimming samples.

Cheers!

[ctalmeida]

Hi Mark,

Sorry the delay on this answer.

Thanks a lot, your explanation is very nice.
I always get confuse with this codec stuff, I will look at the Audacity.

Looks like the right way to go is later buy tape recorder that will work always (no codecs).

Thanks a lot

Carlos