WIP: VIC-2020 MINIMON cartridge

[Mike]

I operated MINIMON with one of my Mega-Carts for a comprehensive suite of tests. While doing so, I (re-)extracted the MC-specific version of TRON with a freeze reset:



Unlike the original version as contained in my Games collection, the MC-version of TRON (download) is internationalized and features English or German instructions at the title screen.

With the page-wise ASCII memory display (one of MINIMON's transient tools) I also found a hidden game that appears at $7000 when VICMON at $6000 is activated. This happened to be yet another variant of City Crusher.

For completeness, here's a closeup of the controls:

[nbla000]

I operated MINIMON with one of my Mega-Carts for a comprehensive suite of tests. While doing so, I (re-)extracted the MC-specific version of TRON with a freeze reset:

You could ask me

With the page-wise ASCII memory display (one of MINIMON's transient tools) I also found a hidden game that appears at $7000 when VICMON at $6000 is activated. This happened to be yet another variant of City Crusher.

Yes, City Bomber, it is on the EXTRA section (F2 from the initial screen to access to this section)

I'm happy you still enjoy your Mega-Cart along with your MINIMON cartridge

[Mike]

You could ask me.

For unknown reasons I did not keep a copy of the adjusted version. Anyway, extracting the game made an interesting test case for MINIMON.

Yes, City Bomber, it is on the EXTRA section (F2 from the initial screen to access to this section)

Indeed, there it is. I only searched in the cartridge and tape/disk games but missed out this one.

I'm happy you still enjoy your Mega-Cart along with your MINIMON cartridge.

Yes, I operate my VIC-20 with MC and a C64SD most of the time.

A cartridge like Mega-Cart, with extra logic for RAM or ROM banking is a much more demanding test case than a standard RAM expansion. The I/O de-multiplex logic of the MINIMON cartridge ensures a minimal delay (only about 5 ns) on the I/O2 and I/O3 select signals when the switch is set to the "CART" position.

I expected MC to init its internal banking registers for "no RAM expansion" and "Mega-Cart firmware in BLK5" when it receives a hardware reset signal, either from its own reset circuit or from the VIC-20 reset circuit. In case of a MINIMON freeze reset, the reset line is opened and pulled high in direction to the cartridge in the extender - thus that cartridge, MC in particular, should keep its own selected RAM/ROM configuration prior to the freeze reset. That is exactly what happens: if I select "no RAM expansion" from the MC menu, a freeze reset keeps that (and puts me at the normal start-up banner of BASIC), if I select "+32K RAM" before, a freeze reset will keep the +32K RAM config as well, and if a cartridge game has been selected before, it is still mapped in after freeze reset. Then I set the switch to "MON" and inspect the cartridge memory.

[chysn]

P.S. there is enough room around the EPROM to accommodate for a ZIF socket as in the first PCB prototype. It is just 24-pin ZIF sockets do have long delivery times at the moment ...

If you're going to start selling soon, a regular socket will probably be sufficient. How often are people really going to swap out MINIMON? Not very. Geez, I can hardly get 2732s that actually work. I've pretty much given up on 24-pin anything. MINIMON is likely to just stay there forever when I get my copy.

[Mike]

To all concerned:

MINIMON has been released on sourceforge, under the CC-BY-SA 4.0 licence.

Greetings,

Michael

[Mike]

Here is the draft of the first hardware design, should anyone want to replicate the prototype cartridge shown in the introductory post of the thread using a VIC-1210 +3K RAM expansion as carrier:

Code: Select all

        2716
    +----\/----+
 1 -|A7     Vcc|- 24
 2 -|A6      A8|- 23
 3 -|A5      A9|- 22
 4 -|A4     Vpp|- 21
 5 -|A3     /OE|- 20
 6 -|A2     A10|- 19
 7 -|A1     /CS|- 18
 8 -|A0      D7|- 17
 9 -|D0      D6|- 16
10 -|D1      D5|- 15
11 -|D2      D4|- 14
12 -|GND     D3|- 13
    +----------+

- open pad 12 lower
- close pad 12 upper, connect Pin 21 (Vpp) to +5V

- open pad 5 (-> pin 20 upper chip, /OE)
- open pad 11 upper (-> pins 18 upper and lower chip, /CS)

/CS := /I/O2 & /I/O3 == //(/I/O2 & /I/O3) -> to pad 11, right
/OE := /(CR/W & SO2)                      -> to pad 5, right

You find the firmware here.