Search found 33 matches

by Richardc64
Tue Nov 03, 2015 6:27 am
Forum: Hardware and Tech
Topic: UltiMem
Replies: 201
Views: 38181

Re: UltiMem

brain wrote:registers have moved a bit:
Awesome work.
I don't see any mention of 3K. Have you eliminated that feature?
by Richardc64
Tue Sep 22, 2015 3:43 pm
Forum: Hardware and Tech
Topic: UltiMem
Replies: 201
Views: 38181

Re: UltiMem

8MB FLASH ROM 1MB SRAM The memory is organized in 5 "windows": RAM1/2/3, BLK1, BLK2, BLK3, and BLK5. Each "window" can be configured to show any 8kB RAM or FLASH ROM page in the memory space Well, this certainly blows away my plan to upgrade my internal memory expansion. Too bad...
by Richardc64
Sat Aug 01, 2015 10:00 am
Forum: Hardware and Tech
Topic: usefulness of partial inhibition (and not all) of the writing on the RAM expansion
Replies: 12
Views: 1266

Re: usefulness of partial inhibition (and not all) of the writing on the RAM expansion

The possibility of buss contention still exists in the simple design, Yogi. VR/W goes low -- if it's going to go low -- near the end of SO2. (PH2) /CS will go low at the start of SO2, and so will the SRAM /OE, putting data on the buss at the same time as the 6502. The duration of this contention wil...
by Richardc64
Fri Apr 24, 2015 4:20 pm
Forum: Hardware and Tech
Topic: Purpose of the vrw pin on the expansion port
Replies: 20
Views: 3146

Re: Purpose of the vrw pin on the expansion port

According to Sam's CompFacts, /IO2 and /IO3 as well as the VIA chips CSs are generated by decoder UC6 which is enabled by the CA 15:13 bit pattern. So these signals would go active as soon as the address pattern matches; regardless of the clock phase. OTOH the UC5 address decoder, for the /BLK sele...
by Richardc64
Fri Apr 24, 2015 4:38 am
Forum: Hardware and Tech
Topic: Purpose of the vrw pin on the expansion port
Replies: 20
Views: 3146

Re: Purpose of the vrw pin on the expansion port

Oh, this is a bit confusing to me. I guess I had misunderstood the need for the 65245 xceivers, I thought they provided bus isolation when the 6502 was in RDY state to accommodate the VIC-1. RDY is pulled up and unused in the VIC-20 and irrelevant to this discussion. The rest of your summation seem...
by Richardc64
Wed Apr 22, 2015 4:37 pm
Forum: Hardware and Tech
Topic: Purpose of the vrw pin on the expansion port
Replies: 20
Views: 3146

Re: Purpose of the vrw pin on the expansion port

I am also considering banking with the option to WP selected BLKs. I see two ways to do it: By preventing the RAMs' /WE from going low, or by preventing /CS going low and thus not enabling the RAM at all. I'm leaning toward the 2nd method as it avoids buss contention -- a possibily that the VIC's de...
by Richardc64
Wed Apr 08, 2015 1:10 pm
Forum: Hardware and Tech
Topic: vic-1110 8k ram cart upgrade (and other solutions)
Replies: 59
Views: 10770

Re: Re:

Hi , new here but have been reading for a bit and for VIC this IS the place to be! I had to jump in here. Last week decided to dig my VIC out of storage and get VIC Tracker running on it. So looking for a RAM Expansions, found Ruud's pages, http://www.baltissen.org/newhtm/memv20.htm also linked her...
by Richardc64
Sat Dec 06, 2014 5:12 pm
Forum: Hardware and Tech
Topic: Purpose of the vrw pin on the expansion port
Replies: 20
Views: 3146

Re: Purpose of the vrw pin on the expansion port

I see your point about the use of these signals internally to the Vic20 but this still doesn't explain to me why put it on the expansion port. What is possible with this pin that otherwise would not be possible? Versatility? Convenience? If one were building some I/O device using discrete logic -- ...
by Richardc64
Thu Dec 04, 2014 8:56 am
Forum: Hardware and Tech
Topic: Purpose of the vrw pin on the expansion port
Replies: 20
Views: 3146

Re: Purpose of the vrw pin on the expansion port

A better question might be why did Commodore call it "V"r/w, since the VIC IC only reads, and does not write. VR/W is narrower than CR/W, because it is "qualified" with Phase2, and is best used for accessing expansion bus RAM. CR/W would be used with external I/O chips that have ...
by Richardc64
Sun Jul 13, 2014 9:25 am
Forum: Hardware and Tech
Topic: My mod from yesteryear
Replies: 13
Views: 2812

Re: My mod from yesteryear

Would that mean it would be possible to boot the Vic, copy the character rom to ram, load and overwrite with a custom character set, flick a switch and use the Vic with a custom character set? In my modification mechanical switches were used only to configure the normally expandable areas; RAM1,2,3...
by Richardc64
Sun Jul 06, 2014 10:35 am
Forum: Hardware and Tech
Topic: My mod from yesteryear
Replies: 13
Views: 2812

Re: My mod from yesteryear

Cool, would you care to share your schematic? The schematics of Richardc64s internal expansion are found on his site . As ambitious as this mod is, it would have been helpful if Richardc64 also had provided some software at least to demonstrate the advantages of doing those mods. That is something ...
by Richardc64
Thu Jul 03, 2014 12:53 pm
Forum: Hardware and Tech
Topic: My mod from yesteryear
Replies: 13
Views: 2812

Re: My mod from yesteryear

I did something similar around the same time. I used an 8kx8 with 3k of it as RAM1,2,3 and 4k "under" the Character ROM so I could have custom characters without using any "main" memory. I've since thought of a way to have both VID accessible internal 3K OR normal external 3k not...
by Richardc64
Tue Dec 03, 2013 5:40 am
Forum: Programming
Topic: Challenge: Create or Delete Lines from inside a program
Replies: 27
Views: 4582

Re: Challenge: Create or Delete Lines from inside a program

Jeff, for what reason would you want to delete, add, or possibly also modify lines from within a program, How about after filling a largish array with initial values from DATA statements, deleting the DATA lines and the FOR-READ-NEXT so there'd be more memory available for other variables. Could be...
by Richardc64
Thu Sep 19, 2013 12:23 pm
Forum: Hardware and Tech
Topic: vic-1110 8k ram cart upgrade (and other solutions)
Replies: 59
Views: 10770

Now how cool is this? I had no idea you had registered here on Denial! :D End of last year, I posted a link to your site in the thread ' What is happening here? '. My mothballed VIC has 76.5K inside. I missed that. I had to reactivate my account. I first registered when I saw that wimoos had incorp...
by Richardc64
Tue Sep 17, 2013 3:46 pm
Forum: Hardware and Tech
Topic: vic-1110 8k ram cart upgrade (and other solutions)
Replies: 59
Views: 10770

If you have a VIC-20cr, you can actually have the 32k x 8 installed inside your VIC by piggybacking it on top of one of the 2 2k x 8 SRAM chips and add the 74LS08 somewhere on top of the glue logic chips. You'll get a VIC-20 with internal 32k ram expansion. My mothballed VIC has 76.5K inside. http:...