VICTerm 4.0 (PAL Patch)

I really like "surfing the internet" with my old computers. Actually, it is dialing into BBSes and browsing their contents with a terminal program and a Wifi-Modem.

The Terminal Program, that I am using for the VIC-20 is VICTerm 4.0, which I have downloaded from zimmers.net. The original is an NTSC version, thus, the position of the screen is not so great in a PAL machine.

VICTTERM 4.0 (NTSC) on a PAL VIC-20

Download of my modified version: VICTerm_4_0_A000_PAL

This is an EPROM image, which can be programmed into an EPROM for the Super Expander II, the Hyper Expander or any other EPROM cartridge, that can hold a 4k (or 8k) EPROM image, which is attached to /BLK5 (address $A000).

I have done the modification with the help of the C64Studio disassembler tool. I looked through the code. It was actually not that compicated. the VIC (VIC is the Video Interface Chip) address $9000, which is called VICCR0 holds the horizontal position. So I was looking for an access of this VIC register.

First patch: $A889: $07 became $0E

Since there is a 23 and a 40 column mode, I have to find a 2nd location.

Second patch: $A79F: $05 became $0C

I have also found, the vertical position of the active screen should be changed. This happens at VIC address $9001, which is called VICCR1. This was not explicitely accessed, but there was a table of 14 values that were written into the other VIC registers (except VICCR0). The table is located at $A86A and has a length of 14. The loop, that writes the values is located at $A874.

Third patch: $A86A: $1B became $28

Since there are two modes, I had to find a 2nd location.

Fourth Patch: $A7A4: $19 became $26.

The table of 15 bytes is located at $A7A4, the routine, which writes it to the VIC can be found at $A78E.

VICTERM 4.0 PAL patched (40 column mode)

VICTERM 4.0 PAL patched (22 column mode)