Right now, I have to power on, type a 'g' command (g E000) and it launches my thing. I can get it to auto-start, but it's a bit of a one-way process and if it doesn't work I'd need to take the EEPROM chip out to reset it - although I have that technology, so maybe I shouldn't be too scared...
I installed a debounced push button in the SBC I worked years ago, so if pressed, +VCC wouldn't reach the EEPROM chip so it wouldn't allow the system to autoboot and go for the internal monitor instead. If left alone, the system would boot from the EEPROM after finding 'WDC' in the right place
the 65C134 is 65C02 based, the 65C265 is 65C816 based.
I haven't used the premade SBCs from WDC before, but i still have a discrete 65C265 lying around that i do want to use for a board similar to WDC's, but better (1MB of RAM, more Flash, FT240X instead of an internal UART, DS1086 Programmable Clock, maybe some other stuff too)
but the architecture of these chips is pretty convoluted.
especially trying to boot of an external ROM, i still don't fully understand how that is supposed to work with the BE pin state during reset and stuff.
very weird stuff
There are two nice things about the W65C265 - the upper address bytes are not duplexed like a standard ‘c816, and it has a neat BBC tube-like parallel interface for expansion and coprocessors. However, the SXB board is only clocked at a little under 4mhz for some reason. So, I built my own board, running at a full 8mhz, with UARTs at .5mbps. Fun little thing!
Have you tried running it faster? from what i remember WDC said that it would very likely run a lot faster than 8MHz, but they never bothered to check.
If i were to use the '265 i have lying around i would definitely aim for like 12-16MHz.
Have you tried running it faster? from what i remember WDC said that it would very likely run a lot faster than 8MHz, but they never bothered to check.
If i were to use the '265 i have lying around i would definitely aim for like 12-16MHz.
I've no doubt the '134 would run much faster, however it's already on a board in my case. Another little niggle I have is the requirement to have 2 clocks - although I may have read the documentation incorrectly, but it seemed to me that I must start from the slow clock then the fast clock must be at least 4x the slow clock to work.
If you could put the high mhz clock into the first clock and ignore the 2nd then that's probably a good solution though
So, I built my own board, running at a full 8mhz, with UARTs at .5mbps. Fun little thing!
Are you deliberately teasing us? Please share a schematic and photos, or any other details you can provide! (A new thread may be in order.) And of course we're dying to hear about speeds above 8 MHz, if you get a chance to investigate that.
Are you deliberately teasing us? Please share a schematic and photos, or any other details you can provide! (A new thread may be in order.) And of course we're dying to hear about speeds above 8 MHz, if you get a chance to investigate that.
Are you deliberately teasing us? Please share a schematic and photos, or any other details you can provide! (A new thread may be in order.) And of course we're dying to hear about speeds above 8 MHz, if you get a chance to investigate that.
I was looking at W65C134 in Mouser and I noticed the Mouser part number says W65C134S8PLG-14. I think "S8" means 0.8u technology and -14 means 14MHz? Even though the datasheet says -8 meaning 8MHz? Has anyone built a board with W65C134 and tried 14MHz or faster?
Bill
I was looking at W65C134 in Mouser and I noticed the Mouser part number says W65C134S8PLG-14. I think "S8" means 0.8u technology and -14 means 14MHz? Even though the datasheet says -8 meaning 8MHz? Has anyone built a board with W65C134 and tried 14MHz or faster?
Bill
S8 means it has a static 0.8µ core, which would have been produced by Sanyo. That’s old stuff, as WDC switched to 0.6µ some 15 years ago. Current production is TSMC 0.6µ, signified with S6T in place of S8, the T meaning TSMC.
I thought the same about the 65C51 - the datasheet only list speeds up to 4MHz but the part number that's available is rated for 14MHz. I think they don't keep the datasheets up to date.
S8 means it has a static 0.8µ core, which would have been produced by Sanyo. That’s old stuff, as WDC switched to 0.6µ some 15 years ago. Current production is TSMC 0.6µ, signified with S6T in place of S8, the T meaning TSMC.
Thanks for the explanation.
W65C51 also has -14 designation. I know it will work at 7.37MHz, but it won't work at 14.7MHz, so -14 may not mean much.
Bill
S8 means it has a static 0.8µ core, which would have been produced by Sanyo. That’s old stuff, as WDC switched to 0.6µ some 15 years ago. Current production is TSMC 0.6µ, signified with S6T in place of S8, the T meaning TSMC.
Thanks for the explanation.
W65C51 also has -14 designation. I know it will work at 7.37MHz, but it won't work at 14.7MHz, so -14 may not mean much.
Well, the -14 is supposed to mean it’s rated for speeds up to 14 MHz. The 0.8µ cores apparently faltered right above 14 MHz, which would explain what you are seeing.
As for WDC data sheets, they never seem to quite match what the product can do and sometimes almost seem to contradict reality.
Please share a schematic and photos, or any other details you can provide! (A new thread may be in order.) And of course we're dying to hear about speeds above 8 MHz, if you get a chance to investigate that.
