As I was "thumbing" through funet this morning, I came upon the schematics for the IEEE interface modules for the VIC-20 and C64.

In case anyone is looking for parts to fix their boards, many manufacturers have EOLed their GPIB interface chips. National discontinued them 6/99 (SN75160/161), and I can't find *any* reference to the MC3446 chips used in the VIC interface on the Motorola Web site. And as we all know, the MOS 6525 TPI can't be found.

What I did find, however, is a Web site, http://www.gpib2000.com//

These guys make a 40-pin GPIB interface chip which includes all of the line drivers and logic to add a complete IEEE interface to a microcomputer/microcontroller. I will review the data sheets shortly.

This raises an interesting question. In the VIC/C64 interfaces, what did the ROM code provide? Was it only protocol code, or was there Commodore-specific driver code in there? Any clues??

Rich

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

How does the Motorola 68488 fit into the scheme of things?
My local surplus dealer has had these in the past, and may still have them.

Pete

Pete:

I don't really know how it fits in. When I searched the Motorols SPS site and ChipCenter.com, it didn't show up as a current product.

Rich

_________________
Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

Rich,

I have often thought about adding a Commodore serial bus or IEEE-488 to 6502 projects for access to storage devices. I'd probably prefer the serial bus because the interface requires far fewer I/O lines and devices are much more readily available (1541s).

To answer your question, in the case of my VIC-20's IEEE cartridge, there are two 6522s for the interface and a ROM which is simply a KERNAL patch with Commodore's IEEE-488 protocol.

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- Mike Naberezny (mike@naberezny.com) http://6502.org

There are a few IEEE488 interfaces on my homepage, on
http://www.6502.org/users/andre/ieee488/index.html

They mostly use 6522 and 6521, one a 6525, some 75160/75161 drivers, others simple open collector with resistor arrays (which might be out of specs, but works...)

One is even for the PC printer port - I use my PC as harddrive for my C64

Andre

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Author of the GeckOS multitasking operating system, the usb65 stack, designer of the Micro-PET and many more 6502 content: http://6502.org/users/andre/

yes it is a IEEE all in one chip COOL part.

bill