RE: Additional cartridge ROM question

RE: Additional cartridge ROM question

From: Bil Herd <>
Date: Wed, 25 Mar 2009 09:41:36 -0500
Message-ID: <>
Back in the day I never found a cartridge that wouldn't load or we would have tried to fix it. I am not counting the issues later because I didn't hide the extra VIC registers and I supposed other things have cropped up over the years as well, but back then the only issue I knew about was Escape from Fractalus because they overwrote a whole 256 block to write 32 VIC registers.

We found we couldn't "fix" bad signals as people had designed using them, for example the Welland Curah speech cartridge used the glitch on the /IO1 line to clock the status of the R/W line.  When I removed the glitch to make it a legal address/IO space strobe I broke their cartridge, so one of my 6 jumpers I went to FCC with was re-glitchifying the I/Osel lines.

With that said I wouldn't be too surprised of anything an extender does, there is legally no hold time on the data lines when clocked by PHI2 as it is, so if the delays are inconsistent then what already is a timing violation gets worse.  The C128 used faster drivers which can make things worse for designs that counted on capacitance to hang on to signal states longer.

We had to have the C= because if a cartridge did anything but ground one of the ROM/GAME lines statically there was a chance we couldn't see it.

I never actually heard of any of the modules you mentioned, they were after my time. :)  I used to keep a Mach 5 speed loader cartridge in my back pocket as it knocked the system under test into C64 mode reliably but also sped it up for testing.

-----Original Message-----
From: [] On Behalf Of Anders Carlsson
Sent: Wednesday, March 25, 2009 8:13 AM
Subject: Re: Additional cartridge ROM question

Bil Herd wrote:

> On the C128 MMU, EXROM and GAME are general purpose input/output pins.

This is perhaps a bit off-topic, but does anyone have experience with
various fast loader/freezer cartridges and which computers they work on? I
have at least a breadbox C64, a C64C, a C128, a C128D (all PAL) and a NTSC
SX-64. In the array of cartridges and expansions I've tried a TFC3, an AR6,
a Handic SuperBox expansion and some unknown c:a 20 cm extention (!) cord
for the cartridge port.

The test results were a bit erratic. On the regular C64's, I believe all
combinations of cartridges, expansions and the extention cord tend to work
fine. Frankly I haven't really tried the regular C128, but on the C128D I
seem to remember the AR6 wouldn't boot properly, at least not when connected
through the extention cord. Since its cartridge port is in the back, far
away from the user I thought it would be sweet if the cartridge could be
accessed in a simpler manner.

On the SX-64, the AR6 built in fastloader freezes instantly. Perhaps it is
due to the machine is an NTSC one while the cartridge is meant for (??) PAL
machines. The TFC3 however worked fine and would load programs using its

Would all this be funny coincidences, or at least in the case of C128
anomalities have anything to do with how it boots and reads the signals?
Unfortunately I sold my last TFC3 a few months back but I could always go
shopping for another one since I found it most compatible with the "oddball"
C64 compatible computers. Besides the sd2iec based devices support the TFC3
fastloader but not the AR6, but that is another topic.

Best regards

Anders Carlsson

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Received on 2009-03-25 14:55:29

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