recently refurbished Datasettes. Looking around, I found this page, where the author had used a Commodore 64 to assist in the transfer process.
- NEW - clears existing programs
- 0 REM - start a new program with line 0
- LOAD - load the program
- SYS 1024 - start the system monitor program
- M 0401 0408 - display memory from address 0x0401 to 0x0408
- cursor up and change the line to start :0401 01 08 - this points to 0x0801, the address where the code from the C64 was loaded
- X - exit the monitor
- 0 - remove line 0 and relocate the rest of the code
- SAVE "name" - save the program to tape
It looks a bit of a faff, but once you've done it a few times, it's quite quick.
- 5V - permanent 5V supply
- Motor - switched unregulated 9V
- Read - data in
- Write - data out
- Switch - connect to GND when play (or any of the other keys) is pressed
So there is a data in and a data out, both TTL level, both pretty much direct to PIA I/O pins. All the analogue stuff is handled in the datasette. So can I just connect them together? It turns out no. Whether by design or mistake, the signals are inverted. I inverted the signal using a 74LS04 inverter and fed the inverted signal into the Pet.
killer poke' code 'POKE 59458,62'. That normally appears at the start of the code, so just remove the offending code before saving. On early Pets, it can speed up the video. This isn't required on the later CRTC based pets, where it causes monitor to lose vertical sync, generating a bright spot or line which could damage the monitor after a while.