Re: VIC-20 "smart" expansion port idea

From: Leif Bloomquist <>
Date: Mon, 11 Jan 2016 10:03:12 -0500
Message-ID: <>
I have one of those VIC-1020s, it's a great idea and neat piece of
hardware, except that the cart slots are inside the case and no way to
control them from the outside!  So you have to lift the monitor off
and open it up to change anything o_O

Plus there was this 5-slot expansion from Hesware [1] with 5 on/off
switches, pretty nice.  With this and a Cardco configurable memory
expansion [2] you could achieve a wide variety of configs, enough to
cover all normal use cases.



Leif Bloomquist | | +1 416-737-2328 | Check out
my blog!

"Every choice, no matter how small, begins a new story." - xkcd

On Mon, Jan 11, 2016 at 2:05 AM, Marko Mäkelä <> wrote:
> On Sun, Jan 10, 2016 at 03:57:23PM -0600, Jim Brain wrote:
>> I have long been intrigued by the Tandy Color Computer Multi-Pak Interface
>> (MPI), and I'd like to try my hand at creating a similar idea for the
>> VIC-20.
> For the record, there already exists a dumb version of this: the Vic-1020
> expansion chassis ("docking station").
> Looking at the schematic diagram, it is pretty simple: two 74LS244 and one
> 74LS245 for buffering the address and data lines, and some logic to drive
> the direction of the 74LS245 data bus buffer.
>> It seems like it would be beneficial to have some control over the
>> cartridge slot, to turn things on/off, or maybe even remap things.  I was
>> thinking of a design where:
>> * 3 switches on the unit would control initial state (on/off)
>> * Users could remap BLK1,2,3,5 to another blk per slot (BLK1 in SLOT 1
>> would actually trigger BLK2, allowing 2 8k RAM expansion to make a
>> 16kB RAM
>> * Users could unmap portions of IO2 or IO3 per slot (effectively fully
>> decoding IO2 so multiple carts at IO2 base could share the space).
>> Yes, probably of limited utility, but I thought it would be interesting to
>> see whether it could be done.
> Isn't this whole hobby of limited utility? How many cartridges are there
> that use I/O2 or I/O3 for something? That is a genuine question; I would
> like to see a list.
> A pragmatic answer could be that a single flash+RAM cartridge would cover
> most needs. The main question seems to be how to use such a mega-cartridge
> together with I/O expansion cartridges. A purist answer is that of course
> you would want some way to plug in multiple original ROM cartridges at a
> time and select which one to play.
>         Marko
>       Message was sent through the cbm-hackers mailing list

       Message was sent through the cbm-hackers mailing list
Received on 2016-01-11 16:00:10

Archive generated by hypermail 2.2.0.