Disassembly of VIC-1112 ROM

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srowe
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Disassembly of VIC-1112 ROM

Post by srowe »

I've finished my annotated source code of the ROM in the IEEE-488 cartridge. I'm somewhat shocked at how sloppy it is, it looks like it was lifted from somewhere else (PET BASIC 4?) and hastily patched. There's loads of dead code and one or two bugs.

Here it is, any corrections etc gratefully received.
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Aturnwald
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Re: Disassembly of VIC-1112 ROM

Post by Aturnwald »

thanks a lot, hopefully this Version works, with my old printer.
Because I've got a old HP Plotter and it is possible to connect that to a VIC. It's done over USER-Port or via IE488 and with the IE488 it doesn't compute, but I saw this working a lot of years ago, so I was thinking that should be to versions of that module one Europe version and one America or Japan, because they told me once, with the cart from Europe it would be work.
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Kakemoms
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Re: Disassembly of VIC-1112 ROM

Post by Kakemoms »

Very interesting disassembly!

Wonder what the programmer thought when he used $9c00 and $9c01 to store variables.. Maybe he had an expansion while programming and just didn't have good control on that one. :lol:
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srowe
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Re: Disassembly of VIC-1112 ROM

Post by srowe »

Kakemoms wrote: Wonder what the programmer thought when he used $9c00 and $9c01 to store variables.. Maybe he had an expansion while programming and just didn't have good control on that one. :lol:
There has to have been some piece of hardware in the IO3/ space. My hunch it that it was some primitive diagnostic board, perhaps with LEDs so a dev to debug code by writing values to it.
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Re: Disassembly of VIC-1112 ROM

Post by Aturnwald »

the software seems to work with my old plotter, but is there any chance that I can speed up the "Boud rate ?" i mean I've got from the card on RS232 max 1200 B, but is it possible to switch an adapter between the plotter and the rs232, so the adapter can handle 2400 B max ?

Is there a way, or not ?

cheerio Toni
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srowe
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Re: Disassembly of VIC-1112 ROM

Post by srowe »

Aturnwald wrote:the software seems to work with my old plotter, but is there any chance that I can speed up the "Boud rate ?" i mean I've got from the card on RS232 max 1200 B, but is it possible to switch an adapter between the plotter and the rs232, so the adapter can handle 2400 B max ?
I'm not sure what sort of plotter you have, not a 1520 as that's an IEC device. IEEE-488 is a parallel protocol whereas RS-232 is serial.
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Aturnwald
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Re: Disassembly of VIC-1112 ROM

Post by Aturnwald »

the 1st one is a original Commodore Plotter, but the 2nd one is a HP 7550A A3 Plotter and he has the same age as my VIC-20, the plotter works on MS-DOS, UNIX and all Computers with a serial interface, but he understands HPGL/1 language ( for e.g. PU - Pen up, PD - Pen down .... ) right now on Linux it's quite hard to get a correct plot, because the system is to new and the plotter to old. I figured out the right way on Linux, so that's OK, but I'd like to run the plotter on my VIC-20, so that it's real easy, with the modem card, the plotter can handle from 300 baud till 9600 baud. So I was thinking, if I speed up the modem, the plotter works faster, so I mustn't wait a long time for the file-/program transfer to the plotter.
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Mike
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Re: Disassembly of VIC-1112 ROM

Post by Mike »

It's really necessary to proper distinguish between:

- the CBM IEC "serial" bus, which is normally used to connect to disk drives and printer,
- RS232 serial interface, which is available on the user port (with TTL levels), and
- IEEE488 (or GPIB), which is possible on the VIC-20 with, say, the VIC-1112, and is a 8-bit parallel protocol.

IEEE488 has an own communication protocol with clocks and handshake, and the speed is governed by master and slave. There are no Baud settings here I know of.

If anything, you'll have to use the userport with a VIC-Modem and connect your HP plotter to that combination. From there, you'll have to program the RS232 KERNAL routines (with OPEN, RS232 is device #2) for a given Baud rate and byte size, and parity, etc. This is all documented in the Programmer's Reference Guide. You then send commands to the plotter as expected with PRINT#.

In any case, the VIC-1112 thread here is the "wrong construction place" for this. ;)
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Re: Disassembly of VIC-1112 ROM

Post by Aturnwald »

I know, VIC-1112 ROM, I've got it since I'm 12 years old, and on that Interface ( I put this in the modul port on my VIC-20 ) I have on one end of the module another module plugged in, and the 2nd module changes the TTL- and also the parallel stuff to a real serial connection, and with this 2nd module I use the plotter, also it is possible for the VIC-1112 ROM to communicate with the HP 7550A Plotter directly, you only must change some wires on the back of the plotter, for e.g. HP-Listen ..... that the plotter works with that module without a 2nd module insert. But, when you use it directly, you are unable to change the speed. But you can connect via the plotter two VIC-20's.

I explain, for many years, there was a graphic-table for the VIC-20 and C64 available from HP, with this graphic-table and a HP-Printer / Plotter, you can draw, electronic-stuff and draw houses ect. save it to tape or disk and print / plot it out. ( I think on a 64'er magazine, one of the early ones there is a small article of that graphic board ) The complete printing / plotting procedure was over the HP-Graphic-Board and a HP Module, that's all.But the Graphic-Board costs the same money as the plotter costs ( 7.500 pound ), also HP sold only 20 boards in west Germany, a few one in UK. So I didn't have such graphic-board, but the lovely plotter and he works but really slow.
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