Search found 12 matches

by zeefour
Mon Jun 21, 2021 10:21 pm
Forum: General Discussions
Topic: An interesting price for W65C02SXB boards
Replies: 18
Views: 2268

Re: An interesting price for W65C02SXB boards

Just to steer things back on track (maybe). My original post was NOT about a price increase. The W65C02SXB is a full SBC not a microprocessor. See:
https://www.amazon.com/W65C02SXB-Engineering-Development-System-Board-Microprocessor/dp/B00ZRTPG44

It's the "65.02" price that was the original point ...
by zeefour
Sat Jun 19, 2021 11:28 pm
Forum: General Discussions
Topic: An interesting price for W65C02SXB boards
Replies: 18
Views: 2268

An interesting price for W65C02SXB boards

While I was poking around today I noticed that both Mouser, Digikey and Amazon have Western Design Center's W65C02SXB SBC priced at $65.02.

I wonder if one did it first and the rest matched the price or if it's was WDC's idea... File under "I see what you did there.." :D
by zeefour
Tue Jun 15, 2021 7:35 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

An update to my update :D

I made a successful port of the SAMD21 emulator to a couple of Adafruit RP2040 boards. These platforms run approximately equivalent to a 2.5Mhz system, so it's now comparable to a good system from back in the day (or my 6502 Badge). Also, it has more RAM so I can get the ...
by zeefour
Mon Jun 07, 2021 7:09 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

Just a quick update that I was glad to see Adafruit has a new run of Neo Trinkey's back in stock. So it isn't discontinued. I'm waiting to get a rp2040 Trinkey that they have coming soon, which should keep the same small Trinkey format, but have a substantially improved CPU with more ram and faster ...
by zeefour
Fri Jun 04, 2021 8:22 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

Looking at the original emulator code (largely untouched), the only potential major inefficiency I see is that the opcodes are parsed as a long switch statement (shades of old Windows programming *grin*). A lookup table might be faster and I have plenty of room for one. But in reading a bit about ...
by zeefour
Fri Jun 04, 2021 8:10 pm
Forum: Emulation and Simulation
Topic: Apple I emulator for SAMD21 boards now available on GitHub
Replies: 1
Views: 2920

Apple I emulator for SAMD21 boards now available on GitHub

I started a new thread so this wasn't buried in the previous discussion.

The code for my Apple 1 emulator on the Adafruit SAMD21 boards is now available at:
https://github.com/rkincaid/a1plus

The system has been built and tested on Adafruit Trinket M0 and Neo Trinkey boards. It includes three ...
by zeefour
Wed Jun 02, 2021 8:55 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

I was not saying write it in assembly language, but that an emulator developed for the most common Arduino likely had too many tradeoffs made in favor of small size instead of speed to shoehorn it into 32K of code and 2K of static RAM. Decisions such as excessive factoring into too many subroutines ...
by zeefour
Tue Jun 01, 2021 4:52 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

If that emulator was written to run on a classic Arduino based on an AVR microcontroller, many tradeoffs were probably made for smaller code size rather than faster speed. If you incorporate one written for the Cortex or ARM, you can likely make it several times faster.

Well the main compromise ...
by zeefour
Mon May 31, 2021 11:08 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Re: Apple I emulator on tiny SAMD21 boards

I should add before anyone gets their expectations raised... I didn't write the underlying emulator. I modified the one floating around for arduinos by Mike Chamber (miker00lz). My project is more systems integration and packaging. Although I did figure out some potentially useful tricks for loading ...
by zeefour
Mon May 31, 2021 9:01 pm
Forum: Emulation and Simulation
Topic: Apple I emulator on tiny SAMD21 boards
Replies: 12
Views: 1674

Apple I emulator on tiny SAMD21 boards

While working on a real 6502 I got sidetracked by a lonely Adafruit Trinket M0 sitting on my desk doing nothing. I wondered if I could get a working Apple I emulator onto it. If you're not familiar with the SAMD21 chip it is based on, it has a reasonably high clock rate and a fair amount of flash ...
by zeefour
Thu May 13, 2021 5:39 am
Forum: Hardware
Topic: Skinny 64K SRAM Chip, W24512AK-10 $0.50 (including shipping)
Replies: 17
Views: 5899

Re: Skinny 64K SRAM Chip, W24512AK-10 $0.50 (including shipp

The pin assignments are close enough to a EPROM to place under the EPROM resulting in a smaller board, and short fast connections. At 50 cents, just solder the part directly to the pc board; EPROM is always socketed anyway so that takes no additional vertical space.
Bill
I'm pretty sure a lot of ...
by zeefour
Thu May 06, 2021 6:58 pm
Forum: General Discussions
Topic: Introduce yourself
Replies: 716
Views: 418854

Re: Introduce yourself

Here's a quick howdy, some background and why I'm here...

I recently got an itch to build something during COVID, so I bought one of the VCF's 6502 Badge kits. Well that build went great. Powered up first try (much to my amazement :D). That kicked in a renewed 6502 passion. Not being satisfied to ...