My first Cartridge...

[Noizer]

SmartRAM looks great, but please can you tell me more about Minimon...

Not I, but Mike is the leader about:
viewtopic.php?f=11&t=9325&hilit=Minimon#p104387

[Robbie]

Ooooooooooo.....

[Robbie]

The 4K wAx image that you have is assembled for Block 3 ($6000). If you do want wAx in block 5, you'll have to re-assemble it with XA, having set * = $a000 on line 40.

I've just got my hands on a Vixen Motherboard cartridge expander which has a built-in PROM socket, but it inserts the PROM at $A000-$AFFF.

Please can you recommend a XA so that I can have a go at assembling wAx to that address. As you can guess, this is more new territory for me.

(or is XA a thing? Have I just been Really Dopey?)

[Mike]

Please can you recommend a XA so that I can have a go at assembling wAx to that address. As you can guess, this is more new territory for me.

(or is XA a thing? Have I just been Really Dopey?)

Here's what xa is.

I've just got my hands on a Vixen Motherboard cartridge expander which has a built-in PROM socket, but it inserts the PROM at $A000-$AFFF.

Your +35K RAM expansion will also 'talk' at that address range, which will lead to data bus contention. Simultaneous operation not recommended.

[chysn]

(or is XA a thing? Have I just been Really Dopey?)

@Mike, thanks for providing the link

I tried a lot of different cross-assemblers (for Mac), and XA is the one I settled on until I get around to writing my own. So my stuff is written with XA's idioms and pseudo-ops in mind. My code might need to be slightly modified for other assemblers including (but probably not limited to) changing the .byte and .asc pseudo-ops for data, changing the case of PETSCII quoted strings, changing the syntax of the -loop local label that I use as a convention. It usually won't be back-breaking work--just follow the error messages--but with XA it'll assemble "out of the box."

Those Vixen carts are cool. It would be neat to have one with a ZIF socket. I have a dedicated $a000 cart scavenged from an extra copy of Gorf, which I use to try ROM images of carts that I don't have yet, but I'm always having to pry out my precious 2764s.

[Robbie]

It sounds like, with your vast experience and expertise, it'd be really easy to assemble wAx to $A000...

[Robbie]

Ahhhhh, hold on... I think I have an oldish mac somewhere in the loft.

I shall have a grapple with XA and, fingers crossed, I won't need to beg and offer beer / chocolate / sexual favours after all...

[chysn]

Ahhhhh, hold on... I think I have an oldish mac somewhere in the loft.

I shall have a grapple with XA and, fingers crossed, I won't need to beg and offer beer / chocolate / sexual favours after all...

XA will also run on Windows. (Edit: Well... maybe not. I have no idea. Definitely on a PC in a Linux VM, though)

But here you go! The attached is a binary file that you can burn directly to a 2764 EPROM.

[Robbie]

Thankyou chysn, I really appreciate you doing that for me.

I have to say that in the short while I've been a member of this forum you have all been extremely welcoming - something it seems increasingly hard to find on today's internet! So thanks for your help, your warm welcome, and the benefit of your technical experience (even if it does take me quite a while sometimes to figure out what it is that Mike is telling me!). If we'd had this kind of support in 1982, imagine how much more geeky we'd have all become.

A question for Mike:
If the expander Eprom is mapped to $A000-$AFFF, do you think I might still be able to install RAM at block 5, and have access to RAM at $B000-$BFFF as well as wAx at $A000-$AFFF? I know you said 'not recommended', but... shall I give it a try?

[Mike]

If the expander Eprom is mapped to $A000-$AFFF, do you think I might still be able to install RAM at block 5, and have access to RAM at $B000-$BFFF as well as wAx at $A000-$AFFF? I know you said 'not recommended', but... shall I give it a try?

Here's what happens - both chips will (try to) talk to the VIC-20 when BLK5 is selected, and play tug-of-war with their outputs, and the outcome depends on their technology:

With LS-TTL and NMOS (both types are present in your VIC-20), the low level on each signal takes precedence, and you will get a wired-AND (somewhat uncontrolled, as there are no decoupling diodes present). This won't do any damage but leads to increased current for that output which puts the 0 on the bus. The RAM chip will influence the entire $A000..$BFFF range so you likely won't see what the ROM intends to put on the bus, and depending on whether the ROM is mirrored to $B000..$BFFF you also won't get working RAM in $B000..$BFFF, either. Getting this right needs extra decode logic, neither which is present in your RAM expansion or Vixen motherboard.

With CMOS (likely the case for the EPROM, and very likely for the RAM chip on your expansion), the situation is more delicate: CMOS outputs can drive both levels, low and high, with a good current. When two of those outputs play tug-of-war there (one low, one high), you short these which leads to increased power dissipation, an undefined logic level on the signal line, and in whole this can damage both chips within short time!

So you either won't get the desired result anyway, or you will even damage things if you proceed. Please don't do this.

[Robbie]

Blimey! I won't do this!

[chysn]

Thankyou chysn, I really appreciate you doing that for me.

You bet! It's the least I can do, what with the USPS taking its sweet time to deliver your cartridge.

[chysn]

The version I provided above is a bit old. I checked out the wrong branch on my work computer. It'll still work okay, but might be missing some refinements. But here's the current version in block 5 ($a000).

[Robbie]

The version I provided above is a bit old. I checked out the wrong branch on my work computer. It'll still work okay, but might be missing some refinements. But here's the current version in block 5 ($a000).

Thanks, I shall give this a try.

The cartridge arrived today, and there's definitely something much more special about having the physical media, particularly given the quality of the manual. I'm really impressed; you must rightly be very proud. Most importantly, we sneaked it past the evil customs people at the ironically named "Mount Pleasant Depot".

[chysn]

The cartridge arrived today, and there's definitely something much more special about having the physical media, particularly given the quality of the manual. I'm really impressed; you must rightly be very proud. Most importantly, we sneaked it past the evil customs people at the ironically named "Mount Pleasant Depot".

Ha, cool! Thank you for the kind words. I am particularly happy with how the manual turned out.