This file will describe how to modify Vidtex 4.0C to work with the MSD CIE interface. First, a little background on the CIE. As you may know, the MSD drives can load and save files over the IEEE interface at least twice as fast as is possible with the serial interface. This is because data is transmitted eight bits at a time instead of one at a time. Vidtex loads in 20 seconds, as opposed to 45 with the 1541. The CIE interface works by replacing KERNAL vectors located at $031A - $033A with memory addresses of subroutines that are downloaded into high memory. With my CIE this is accomplished by SYS57278, but this may be different in later versions (in which case you're on your own). The code downloads to $9C00, which is ok if you work only with Basic, but not at all compatible with most commercial software, including Vidtex. MSD must have realized the problem, as they supplied relocator programs and, later, a "Rev 2 Patch" (which I have never been able to get to work with ANYTHING!). These relocate the code to various RAM areas, all of which are overwritten by Vidtex. The only solution, then, is to modify Vidtex so that it will not disturb an area of memory large enough to squeeze in the CIE code - about 1k. The other problem is that the CIE only intercepts KERNAL calls that use the vectors mentioned above. This means that TALK, LISTEN, ACPTR, CIOUT, etc. must be replaced with CHKIN, CHKOUT, CHRIN, CHROUT, etc. OK, enough talk. Let's get down to specifics. Here goes: 1) Download or copy the following files to disk: VIDTEX 4.0C, RLCCIE, and VXCMOD. 2) Activate the CIE by entering SYS57278. 3) Load RLCCIE. It is set up for device 8 to be the only IEEE device. If you want to change this, modify lines 200 & 210 to suit your needs. After you RUN it (this takes about 25 seconds), the CIE code will be relocated to $C800 - $CBFF. Unless you want to go through this every time you load Vidtex, I highly recommend you save the relocated code to disk with a m.l. monitor (located in BASIC workspace). That way you can LOAD it ,8,1, and it will remain there until you turn off the computer or load something else over it. You can re-activate it from BASIC with SYS51257. Or you could do as I did and write it to an EPROM to replace the one in the CIE. 4) Load VXCMOD,8,1 5) Enter "NEW" 6) Load VIDTEX 4.0C, but DON'T RUN IT! 7) Enter "SYS49152". Don't blink, or you'll think nothing happened. This is a very short m.l. program that modifies Vidtex. 8) Thats it! Save the modified program before running it. One final note: You might notice that this program modifies Vidtex to protect $C800 - $CDFF, which is 1.5K, and the CIE code is only 1K. This is to leave space for further expansion and to make the code compatible with a future wedge for the CIE. It will also work with the code at $CA00, as did Vidtex 4.0B modified with Deepak's SUPERZAP and ZBIEEE. Please address all comments, questions, suggestions, etc. to: Andre LeClaire 70356,1445
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