At 20:32 -0600 3/1/13, <Ben> wrote: For Color Computer The Byte article on COCO (original) says 800 mV 1500 bps. Greg Lomont's Color computer guide says: Color BASIC saves a file as a series of blocks, each with 0-255 bytes of data. Some blocks need preceded by a leader to establish timing. Each bit is recorded as a single cycle of a sine-wave. A "1" is a single cycle at 2400 Hz, and a "0" is a single cycle at 1200 Hz. Bytes are stored least significant bit first. Bits are recognized when the sine wave crosses from positive to negative, so loudness is not as important as one might expect. A file consists of: 1. a leader 2. a filename block 3. a 1/2 second gap 4. another leader 5. some number of data blocks 6. an end-of-file block A leader is just hex $80(128 dec) bytes of hex $55 (binary 01010101). A block contains: 1. two "magic" bytes ($55 and $3C) 2. one byte - block type (00=filename, $01=data, $FF=EOF) 3. one byte - data length ($00 to $FF) 4. 0 to 255 bytes - data 5. one byte - checksum (sum of data, type, and length bytes) 6. another magic byte ($55) Filename blocks have $F(15) bytes of data; EOF blocks have zero bytes of data; data blocks have $00-$FF bytes of data indicated by length byte. A filename block contains: 1. eight bytes - the filename 2. one byte - file type ($00=BASIC, $01=data, $02=machine code) 3. one byte - ASCII flag ($00=binary, $FF=ASCII) 4. one byte - gap flag ($00=no gaps, $FF=gaps) (The tech manual incorrectly (?) shows 01 as the code for "no gaps") 5. two bytes - machine code starting address 6. two bytes - machine code loading address There should be no gaps, except preceding the file, and in case the filename blocks requests gaps, in which case there is a 1/2 second gap and leader before each data block and EOF block. Hardware The cassette cable has a 5-pin DIN connector on one end, that plugs into the back of the CoCo; the other end has three earphone-style plugs, that plug into the EAR, AUX (or MIC), and REMOTE jacks. The remote-control plug is smaller than the other two. The other two are differentiated by color: the black one plugs into the EAR jack, while the grey one plugs into AUX. Here is an ASCII drawing of that connector, including a pinout and showing how the pins are numbered. The drawing is of the connector at the end of the cable, with the pins pointing toward you. So if you are looking at the back of the machine, at the connector there, this pinout is backwards. My apologies for the wacky numbering; this is the same numbering as in the CoCo-1 technical manual. ------- Pin# Name Connects to / \___/ \ ---- ------- ----------------------------------- / \ / \ 1 CASSMOT SG stem | | 2 GND B stem, LG stem | 1o o3 | | | 3 CASSMOT SG tip o o \ 4 o 5 / 4 CASSIN B tip \ 2 / \ / 5 CASSOUT LG tip ------- B=black SG=small grey LG=large grey The names are given from the perspective of the computer, so "OUT" means output from the computer, input to the cassette, and it should go into the AUX (or MIC) jack while the cassette is recording. -- - Mark 210-379-4635 ----------------------------------------------------------------------- Large Asteroids headed toward planets inhabited by beings that don't have technology adequate to stop them: Think of it as Evolution in Fast-Forward.