TarableCode
@tarableco.de
Tara.
I write weird code that does weird things sometimes.
Toronto smells weird.
I write weird code that does weird things sometimes.
Toronto smells weird.
e: nm
Seems to be activity now, it looks like it needed a longer reset.
My best guess is that /RESET needs the clock to pulse, and since my reset delay was 10msec the clock wasn't toggling during the reset phase.
Seems to be activity now, it looks like it needed a longer reset.
My best guess is that /RESET needs the clock to pulse, and since my reset delay was 10msec the clock wasn't toggling during the reset phase.
December 15, 2025 at 7:46 PM
e: nm
Seems to be activity now, it looks like it needed a longer reset.
My best guess is that /RESET needs the clock to pulse, and since my reset delay was 10msec the clock wasn't toggling during the reset phase.
Seems to be activity now, it looks like it needed a longer reset.
My best guess is that /RESET needs the clock to pulse, and since my reset delay was 10msec the clock wasn't toggling during the reset phase.
Allright, I hooked everything up and put 3 LEDs on A0-A2 but they are unchanging (2Hz clock).
Something must be up, because the EEPROM is full of NOPs so it should just be acting as a counter.
Something must be up, because the EEPROM is full of NOPs so it should just be acting as a counter.
December 15, 2025 at 7:38 PM
Allright, I hooked everything up and put 3 LEDs on A0-A2 but they are unchanging (2Hz clock).
Something must be up, because the EEPROM is full of NOPs so it should just be acting as a counter.
Something must be up, because the EEPROM is full of NOPs so it should just be acting as a counter.
The active low bars are just for notation's sake right, It's just a simple OR operation?
December 15, 2025 at 6:13 PM
The active low bars are just for notation's sake right, It's just a simple OR operation?
I could have sworn I had a 74'32, but it's not in my new parts. I'll check my scrap boards for one, and if I don't find anything I'll cook up a GAL.
December 15, 2025 at 5:37 PM
I could have sworn I had a 74'32, but it's not in my new parts. I'll check my scrap boards for one, and if I don't find anything I'll cook up a GAL.
I got a little better, I think.
December 14, 2025 at 10:03 PM
I got a little better, I think.
28c64 (to avoid getting out the uv eraser)
61c64
61c64
December 14, 2025 at 10:02 PM
28c64 (to avoid getting out the uv eraser)
61c64
61c64
I’ll have to add the 8255 when I understand how it all fits together.
December 14, 2025 at 8:11 PM
I’ll have to add the 8255 when I understand how it all fits together.
I haven’t set up the brownout circuit yet, but I do make use of a gpio for a 10ms reset pulse.
I think I’ll be okay once I understand the bus architecture; it’s a bit confusing to have peripherals not be memory mapped like I’m used to.
I guess step one is just an eeprom containing NOPs?
I think I’ll be okay once I understand the bus architecture; it’s a bit confusing to have peripherals not be memory mapped like I’m used to.
I guess step one is just an eeprom containing NOPs?
December 14, 2025 at 8:11 PM
I haven’t set up the brownout circuit yet, but I do make use of a gpio for a 10ms reset pulse.
I think I’ll be okay once I understand the bus architecture; it’s a bit confusing to have peripherals not be memory mapped like I’m used to.
I guess step one is just an eeprom containing NOPs?
I think I’ll be okay once I understand the bus architecture; it’s a bit confusing to have peripherals not be memory mapped like I’m used to.
I guess step one is just an eeprom containing NOPs?
Do you mind sharing your z80 schematic?
Just at a glance it seems more intimidating than the 6502, and I'm a bit lost as to where to start.
I did program an ATTiny85 to provide a 512KHz clock that can be divided based on the state of a few pins down to ~128KHz.
Just at a glance it seems more intimidating than the 6502, and I'm a bit lost as to where to start.
I did program an ATTiny85 to provide a 512KHz clock that can be divided based on the state of a few pins down to ~128KHz.
December 14, 2025 at 7:33 PM
Do you mind sharing your z80 schematic?
Just at a glance it seems more intimidating than the 6502, and I'm a bit lost as to where to start.
I did program an ATTiny85 to provide a 512KHz clock that can be divided based on the state of a few pins down to ~128KHz.
Just at a glance it seems more intimidating than the 6502, and I'm a bit lost as to where to start.
I did program an ATTiny85 to provide a 512KHz clock that can be divided based on the state of a few pins down to ~128KHz.
I'll start by getting it fed into a 74'393 and move on when I get something within spec. Gotta desolder the crystal and caps first though, so that'll be a few.
December 7, 2025 at 8:35 PM
I'll start by getting it fed into a 74'393 and move on when I get something within spec. Gotta desolder the crystal and caps first though, so that'll be a few.
Looking at the Z8400PS you gave me, and the internet is telling me it's a 2.5MHz part, is it going to mind that 7MHz crystal?
December 7, 2025 at 8:21 PM
Looking at the Z8400PS you gave me, and the internet is telling me it's a 2.5MHz part, is it going to mind that 7MHz crystal?
Maybe it's time for me to actually just start hooking things up rather than thinking about external clock generation and the like.
I probably have everything I need: z80, '74138, roms, srams, and that 8255 should be good enough for blinky.
I probably have everything I need: z80, '74138, roms, srams, and that 8255 should be good enough for blinky.
December 7, 2025 at 8:10 PM
Maybe it's time for me to actually just start hooking things up rather than thinking about external clock generation and the like.
I probably have everything I need: z80, '74138, roms, srams, and that 8255 should be good enough for blinky.
I probably have everything I need: z80, '74138, roms, srams, and that 8255 should be good enough for blinky.
Those 80c31 boards I have might have a UART friendly crystal, I’d have to try powering it up to find out cause they soldered over the markings.
December 7, 2025 at 7:32 PM
Those 80c31 boards I have might have a UART friendly crystal, I’d have to try powering it up to find out cause they soldered over the markings.
Dang, I don't have any oscillators kicking around of that frequency unless I look on junk boards.
Why 9.216MHz though?
9600*16 = 153,600
Just trying to wrap my head around this; I'm not used to getting this far into clocking yet.
Why 9.216MHz though?
9600*16 = 153,600
Just trying to wrap my head around this; I'm not used to getting this far into clocking yet.
December 7, 2025 at 5:50 PM
Dang, I don't have any oscillators kicking around of that frequency unless I look on junk boards.
Why 9.216MHz though?
9600*16 = 153,600
Just trying to wrap my head around this; I'm not used to getting this far into clocking yet.
Why 9.216MHz though?
9600*16 = 153,600
Just trying to wrap my head around this; I'm not used to getting this far into clocking yet.
YES!
That's going to be so much easier than trying to understand the ch32v003 reference manual this late.
I wonder if I should generate TXCLK/RXCLK and CLK separately, or just divide CLK by something using a '393?
That's going to be so much easier than trying to understand the ch32v003 reference manual this late.
I wonder if I should generate TXCLK/RXCLK and CLK separately, or just divide CLK by something using a '393?
December 7, 2025 at 3:59 AM
YES!
That's going to be so much easier than trying to understand the ch32v003 reference manual this late.
I wonder if I should generate TXCLK/RXCLK and CLK separately, or just divide CLK by something using a '393?
That's going to be so much easier than trying to understand the ch32v003 reference manual this late.
I wonder if I should generate TXCLK/RXCLK and CLK separately, or just divide CLK by something using a '393?
Looking into generating clocks for the i8251 clone I extracted.
December 7, 2025 at 3:53 AM
Looking into generating clocks for the i8251 clone I extracted.
Bah!
Those 3 pins on the left are really holding it in place.
Those 3 pins on the left are really holding it in place.
December 6, 2025 at 6:26 PM
Bah!
Those 3 pins on the left are really holding it in place.
Those 3 pins on the left are really holding it in place.
Source + schematic:
github.com/TaraHoleInIt...
github.com/TaraHoleInIt...
GitHub - TaraHoleInIt/i8255_Blinky: Simple blinky for i8255 driven by ch32v003
Simple blinky for i8255 driven by ch32v003. Contribute to TaraHoleInIt/i8255_Blinky development by creating an account on GitHub.
github.com
December 6, 2025 at 2:42 AM
Source + schematic:
github.com/TaraHoleInIt...
github.com/TaraHoleInIt...
What if the legs aren’t straight and were soldered at weird angles?
December 5, 2025 at 4:50 PM
What if the legs aren’t straight and were soldered at weird angles?
There's a V20 on there too, but I'm nervous about it because of a few bent pins on the back. I might have to handle those manually.
December 4, 2025 at 5:35 PM
There's a V20 on there too, but I'm nervous about it because of a few bent pins on the back. I might have to handle those manually.
That's way more elegant than setting the heat gun to 450c and giving it a few thwacks, but I don't have a hot plate.
I need to find a way to get under the chip and apply a pulling force on it.
I need to find a way to get under the chip and apply a pulling force on it.
December 4, 2025 at 5:34 PM
That's way more elegant than setting the heat gun to 450c and giving it a few thwacks, but I don't have a hot plate.
I need to find a way to get under the chip and apply a pulling force on it.
I need to find a way to get under the chip and apply a pulling force on it.