Micro-Systems' VIE Cartridge VIC To IEEE Interface

Karl Kelley

Have you wanted to add the disk drive for your other Commodore computer to your VIC? If you are like many Commodore owners, you may have already owned a 4016, 4032, or 8032 PET/CBM computer along with a disk drive and a printer.

Micro-Systems Development, Inc. is marketing an interface cartridge which converts the user port to IEEE protocol and allows direct access to IEEE devices of all kinds. My particular interest right now is the IEEE disk drives and printers manufactured by Commodore — the ones I already own.

I ordered the VIE Cartridge from Micro-Systems, and as soon as I received it, I opened the durable plastic case to check out the insides.

Inside were four chips and a female edge connector, mounted on a good quality, solder-dipped printed circuit board with two male edge connectors. The large edge connector plugs into the VIC user port. The female connector mounted on the PC board is a straight through extension of the user port lines. This means that use of the VIE cartridge does not restrict one from later expansion. The smaller male edge connector is that sorely needed IEEE port designed to mate with Commodore's P/I cable.

Note: Though the device is extremely well constructed, care must be used when plugging it into the VIC and especially when plugging additional cartridges into the VIE. Remember, it is only a PC board and cannot be subjected to excessive flexure. The safest approach is to plug the other cartridge into the VIE before plugging the VIE into the VIC.

The instructions consist of one typewritten page with a brief explanation of the device and instructions for enabling/ disabling the interface software. The instructions are entirely adequate.

Once installed, the interface can be enabled via

SYS40000

This actuates the approximately 1K EPROM onboard software. Once enabled, the interface can be disabled by any one of the following:

"RESTORE"

Software BRK

VIC Power Off

SYS64850 (the exit routine)

Recall that VIC BASIC is really a modification of PET BASIC 3.0 and does not contain the direct disk commands of BASIC 4.0 such as DLOAD, DSAVE, etc. So users who have become "dependent" on BASIC 4.0 will have to relearn the syntax of disk operations from the earlier BASICs. For example, to save a program under the name TESTPROG on drive 1, execute the following:

OPEN1, 8, 15, "I1" : SAVE "TESTPROG",8 : CLOSE1

Of course, initialization is not required on the 8050 drives, and if the disk has previously been initialized, the OPEN and CLOSE statements are not necessary.

File handling is straightforward and identical to PET BASIC 3.0. Again, BASIC 4.0 users will miss the random file commands available in BASIC 4.0, but fortunately, the RANDOM 1.0 program (in BASIC) on the Commodore DEMO disk can be copied directly for use on the VIC-20.

There are a few things to watch out for while using the VIE. On the larger Commodore machines, the IEEE port is part of the MAIN LOGIC ASSEMBLY and cannot be enabled/disabled at will. Accidentally disabling the VIE when files are OPENed on the disk or printer can cause loss of data. The convenience of the RESTORE (warm start) key is now an albatross. If you are doing disk operations and hit the RESTORE key (disabling the VIE) while disk files are OPEN, you have accomplished the same thing as unplugging the P/I cable. Under certain circumstances, this could also result in lost data.

Likewise, printer format commands will be lost if the VIE is disabled. This is not a disaster, but it is inconvenient. I have learned to set off these format/ control commands in routines or programs on their own for quick recovery.

The device performs well and in accordance with the manufacturer's specifications. At $79.95, the VIE Cartridge is a valuable addition to the VIC for users who already own Commodore disk drives and/or printers, and for anyone contemplating using the VIC as an IEEE controller.

Micro-Systems Development, Inc.
11105 Shady Trail, Suite 103
Dallas, TX 75229
$79.95