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8008guy
July 12th, 2017, 08:09 PM
I have a tarbell cassette controller card for my Altair 8800. Can anyone point me to cassette audio files that I can use to test and load sw onto my Altair?

Thanks

Len

Dawsoca
July 12th, 2017, 11:34 PM
Hello Len, I would be interested in some Tarbell Tape files as well. There was a very old post requesting WAV files for the Tarbell; but the link has been dead a long time. You should check out the article in Byte Magazine July 1978 that talks about improving the performance of the Tarbell card. There was an adjustment program listed in the article to generate a sync tape which might help you.

> Charles

39707

Tarbell Sync Stream Tape Program:



* TARBELL TEST ROUTINE TO ADJUST INTERFACE
*
CASC EQU 6EH
CASD EQU 6FH
*
* WRITE OUT STREAM OD ALTERNATING
* SYNC (E6H) BYTES AND TEST (22H) BYTES
*
LOOPW MVI B,22H
CALL SUB
MVI B,0E6H
CALL SUB
JMP LOOPW
*
* SUB WILL WRITE TO THE TARBELL
*
SUB IN CASC * TEST STATUS
ANI 20H
JNZ SUB
MOV A,B
OUT CASC * OUT BYTE
RET
*
* TEST PROGPAM = THE TAPE GENERATED
* ABOVE IS PLAYED WHILE PUNNING THIS
* PROGRAM. A SIGNAL (BELL, BEEP, OR
* LIGHT) IMPLIES AN ERROR DETECTED.
*
TEST MVI A,10H
OUT CASC * RESET TARBELL
*
LOOPR MVI B,22H
CALL SUBR * READ BYTE
JNZ MISS * NZ--NOT 22H, ERROR
MVI B,0E6H * 22H, CHECK SYNC
CALL SUBR
JZ LOOPR * SYNC OK, LOOP
*
* 22H MISSED, GIVE AN ERROR SIGNAL
*
MISS CALL SIG * USER SUPPLIED ERR SIGNAL
*
JMP TEST * RESET, RESTART
*
SUBR IN CASC
ANI 10H * BYTE READY?
JNZ SUBR
IN CASD * INPUT BYTE
CMP B * COMPARE
RET
*
SIG DS 20D * ADD SIGNAL HERE
*

8008guy
July 14th, 2017, 04:40 AM
I think I will start with the sync tape program, thanks. At the end of the manual there is also a rom listing that has some combined functionality that may be usefull.

Might there be a program around that will take a binary file and convert it to a tarbell compatable wav or mp3?

Len

Dawsoca
July 14th, 2017, 12:51 PM
Hello Len, from past posts in the forum, it appears that people use the Audio Programs "Audacity" or "Cool Edit Pro" to transfer Tarbell Tape files into WAV files.
There is a long discussion about this from 8/14 titled "Audio Formats for Software". There is another discussion about Tarbell tape files from 7/15 titled
"Tarbell Cassette I/F" where Soupwizard transferred one of his tapes to a WAV format. Unfortunately the link he used it upload the converted WAV
file is long since dead. You might try to contact him.

In general, the best I could determine from the Tarbell Manual on the tape file format is the following...

RULES FOR WRITING/READING SOFTWARE FROM TARBELL CASSETTE TAPE-

*1) 1ST BYTE MUST BE 'START BYTE' = (3C)H
*2) 2ND BYTE MUST BE 'SYNC BYTE' = (E6)H
*3) 'DATA BYTES' ARE SENT NEXT AS SEQUENTIAL DATA
*4) 'STOP BYTE' = (1A)H IDENTIFIED AS SUCH BY IMMEDIATELY FOLLOWING WITH (FF)H
*5) 'CKSUM BYTE' WILL FOLLOW IF USED, OTHERWISE THERE WILL BE (FF)H

* EXAMPLE: FF FF FF FF [3C] [E6] [DD DD DD DD DD DD] [1A] [FF] [CKSUM] FF FF FF

DATA PORT = [6FH] STATUS PORT = [6EH]

I don't know if this works or if this is the Tarbell standard as I don't have a Tarbell Cassette Card to test it on.
The plan is to have a Tarbell S100 PCB card made later this year as it seems cheaper or break even to make the card
instead of purchasing off EBAY.

> Charles

8008guy
July 14th, 2017, 07:07 PM
Thanks Charles