Search found 103 matches

by sjgray
Mon Dec 24, 2018 10:43 pm
Forum: Hardware and Tech
Topic: 6502 Made from 74-Series Logic at 20 MHz
Replies: 2
Views: 4336

Re: 6502 Made from 74-Series Logic at 20 MHz

He also had it working on one of my PET machines at World of Commodore 2018. Incredible!

Steve
by sjgray
Thu Oct 04, 2018 12:34 pm
Forum: Emulation and Cross Development
Topic: 6502bench - new disassembler
Replies: 6
Views: 6116

Re: 6502bench - new disassembler

It does look interesting. If you are looking for something similar with more Commodore support you may already have it.... CBM-Transfer. I don't think many people know of all the features in CBM-Transfer... The majority of 6502bench's main features are included in CBM-Transfer's ASM Viewer, includin...
by sjgray
Mon May 14, 2018 12:06 pm
Forum: Hardware and Tech
Topic: Character ROM replace with RAM?
Replies: 21
Views: 10420

Re: Character ROM replace with RAM?

Would it be possible to swap out the Character ROM for RAM (and then populate from disk/tape)? Sure, that's possible. I assume you want a solution that would work without expansion ram, otherwise you could just put your new character set there and point the VIC to it. You would need to build an ada...
by sjgray
Fri Feb 09, 2018 7:15 pm
Forum: Hardware and Tech
Topic: Speech synthesiser cartridge
Replies: 17
Views: 13201

Re: Speech synthesiser cartridge

Here is a copy of the magazine with the C64 version I made. It could easily be adapted to the VIC-20 if one wanted to. Zipped PDF Radio_Electronics_August_1986.zip Link to archived Radio Electronics: https://archive.org/details/radioelectronicsmagazine I used a version from RUN Magazine to make a s...
by sjgray
Wed Jan 24, 2018 1:34 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

I started an 80-column cartridge for the C64 here: http://www.6502.org/users/sjgray/projects/vyms64/index.html This cartridge uses a Yamaha video chip like used in the MSX2 computers, a Yamaha sound The MSX video chip is a licensed derivative of the TI9918a chip used in the Coleco Adam, TI/99-4a. T...
by sjgray
Wed Jan 17, 2018 3:08 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

Steve, thanks for your interest in completing the project. I'm really the "buy a ready-to-use commercial product only" kind of guy, so I hope your work will inspire someone in bringing forth a 40/80 card for the 21st Century :) . That's totally fine. I'm actually the same way, since I don...
by sjgray
Wed Jan 17, 2018 11:47 am
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

I have completed a preliminary design of the VIC-20 version of my VYMS64 cart. This includes V9958 Video with 64K VRAM, YM2413 Audio, 6551 ACIA RS-232, plus 32K RAM for main VIC memory. Schematics and info is available on my VYMS web page: http://www.6502.org/users/sjgray/projects/vyms64/index.html ...
by sjgray
Mon Jan 15, 2018 5:31 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

It looks lke Eslapion's ram expander uses one 32K chip and a single LS'08... Yes. The Ultimate Expander used a 62256 SRAM IC or equivalent and a 74LS08. Since the BLK 1,2,3 and 5 areas represent 8kBytes each, it is required to re-encode these signals for compatibility with a single 32kBytes memory ...
by sjgray
Mon Jan 15, 2018 1:01 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

Well, I've sorted out the cartridge edge connector footprint. Just need to add the RAM. Anyone know of schematics for a simple 1-ram-chip circuit? I think I have room for a skinny-dip ram and one more chip. It looks lke Eslapion's ram expander uses one 32K chip and a single LS'08... The PCB is alrea...
by sjgray
Sat Jan 13, 2018 6:04 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

A quick look on ebay shows plenty of V9958 chips available in quantity. In the past I've purchased parts from G&C and Polida2008 without any problems. Also funkward-tech can put together the V9958 with whatever supports components you need for a fairly reasonable price (look for "yamaha v99...
by sjgray
Fri Jan 12, 2018 8:23 pm
Forum: Hardware and Tech
Topic: 40 80 column cards
Replies: 22
Views: 8903

Re: 40 80 column cards

I started an 80-column cartridge for the C64 here: http://www.6502.org/users/sjgray/projects/vyms64/index.html This cartridge uses a Yamaha video chip like used in the MSX2 computers, a Yamaha sound chip, and a Link-232 inspired RS-232 circuit. I designed this to learn about the Yamaha V9958 video c...
by sjgray
Mon Nov 13, 2017 3:33 pm
Forum: Hardware and Tech
Topic: VIC-2000 Expander. Modern Power Using Retro Parts!
Replies: 168
Views: 59663

Re: VIC-2000 Expander. Modern Power Using Retro Parts!

Brad, I have a project to generate 256 colours on the PET. While looking into DACs I saw this on your page: http://www.lucidscience.com/projects/VGA%20Video%20Generator/3.jpg I wonder why you use 6 resistors and 6 diodes for Intensity. Could you not just use 2 resistors joined, then split into 3 wit...
by sjgray
Mon Nov 13, 2017 11:25 am
Forum: Hardware and Tech
Topic: VIC-2000 Expander. Modern Power Using Retro Parts!
Replies: 168
Views: 59663

Re: VIC-2000 Expander. Modern Power Using Retro Parts!

Hey Brad, Have you considered demonstrating your stuff at a show? World of Commodore is coming up in December, in Toronto, and there are lots of Denial members coming to the show. I reserved two tables, but now it looks like I may not be able to use one. I bet people would like to see your stuff in ...
by sjgray
Mon Nov 06, 2017 10:55 am
Forum: Hardware and Tech
Topic: VIC-2000 Expander. Modern Power Using Retro Parts!
Replies: 168
Views: 59663

Re: VIC-2000 Expander. Modern Power Using Retro Parts!

Had an hour free this evening, and decided to try my crazy "Remote 6560" idea. I will admit that I only gave this a 75% chance of working. Started by soldering a socket to the ZIF socked so I could attach 40 wires. The idea was that the 6560 could live outside the VIC-20 and at the same t...
by sjgray
Tue Jul 11, 2017 11:54 am
Forum: General Topics
Topic: Additional Sound Chip Suggestions...
Replies: 16
Views: 3901

Re: Additional Sound Chip Suggestions...

I love chip tunes. I know the SID is the big king in these parts (and for good reason) but that doesn't stop me from loving other sound chips like the AY-3-8910 and the SN76489. I also love being "period accurate" as much as I can. Meaning, a 64 voice polyphony sound system on a VIC-20 wo...