
VTL-2 USERS NOTES

As implemented on the HM-68 homebrew 6802 computer

INITIALIZATION

VTL-2 loads at $1C00; this was an arbitrary choice - it could be anywhere.
Once VTL-2 is loaded from SWTBUG, or whatever, you MUST set the '&'
variable once you get an 'OK' prompt, or the program will crash:

&=264  (the start of user RAM)
*=7167 (the limit of the top of user RAM, can be lower)

Often, it is necessary to hit the <RETURN> key multiple times to get the
'OK' prompt.  Don't attempt to run a loaded program with  #=1  until you
have an 'OK' prompt; otherwise, VTL will append whatever you type to the
end of the program in memory.

SERIAL TRANSFER SPEED

Regardless of the baud rate used to load VTL-2 (I use 9600 baud),
you must set character and line delays in your serial terminal emulator
before attempting to 'load' programs from text files.  With the 6802
running at 4 MHz (1 MHz on the bus), I've found that 15 msec character
delay and 300 msec line delay works well.

PROGRAM LISTINGS

Remove all blank lines from program listings.  Yes, this makes the
listing more difficult to read, but when bringing in programs via
serial transfer, it's required: VTL *hates* empty lines and will almost
always mess up the transfer.  Maybe have a nice, pretty, well-commented
listing for human eyes, and another just for loading.
