Your perseverance is outstanding my friend. I must admit when you scoped A7 and it was held high right next to the +5v on the schematic I screamed "short!!! check the board for damage". Well WTF do I know, I'll stick to my comfortable "if" and "case" statements and leave the hardware fault finding to the experts. Great work ;-)
Thanks for the video. Bravo on finding the culprit and fixing the Toastrack. I might be wrong, but it seems you scoped the wrong chip at timeline 6.06, as you were checking pin 27 on the PCF chip, but scoped the Z80.
Hang in there man. Video was great and shows that going off track is easy. We're all stubborn because we want these machines to live for ever but clear thinking wins out in the end. Look after yourself and those you love.
Here is how the memory works: Address lines go to all of the RAM ICs, and they are parallel. There is nothing like certain address line goes to a certain RAM IC, they are all in parallel. The RAM ICs on the Spectrum are 1 bit RAMs, this means they all can hold only the 1 bit of the 8 bit data floating around. So, if you want to write a byte, (for example something like 10011010), to a certain address location on the RAM, you put that address on the address bus, all the RAM ICs receive the same address (remember parallel) and put that byte on the data bus. Now, the data bus is the one that is wired differently, each data line (D0 to D7) goes to only one RAM IC. So, each one of them receives a different digit of the data for the same address, 8 of them working together holds the whole byte, but every digit of it is stored in a different IC.
Another toast-rack saved 👍 I like the "Happy Little Diodes" channel. Posting that 16k Speccy tommorow, later than planned, but it should be with you Monday hopefully.
The 74LS157, I recognize that little bugger... It's the same type of Quad Multiplexer IC which I used in TJ's "The Ultimate Bastard" joystick... or in other words; is used in the 4 button version of a Sega Genesis/Mega Drive controller.
The slow zoom as the test’s were running was cinematic gold.
Your perseverance is outstanding my friend. I must admit when you scoped A7 and it was held high right next to the +5v on the schematic I screamed "short!!! check the board for damage". Well WTF do I know, I'll stick to my comfortable "if" and "case" statements and leave the hardware fault finding to the experts. Great work ;-)
Thanks for the video. Bravo on finding the culprit and fixing the Toastrack. I might be wrong, but it seems you scoped the wrong chip at timeline 6.06, as you were checking pin 27 on the PCF chip, but scoped the Z80.
Hang in there man. Video was great and shows that going off track is easy. We're all stubborn because we want these machines to live for ever but clear thinking wins out in the end. Look after yourself and those you love.
Here is how the memory works: Address lines go to all of the RAM ICs, and they are parallel. There is nothing like certain address line goes to a certain RAM IC, they are all in parallel. The RAM ICs on the Spectrum are 1 bit RAMs, this means they all can hold only the 1 bit of the 8 bit data floating around. So, if you want to write a byte, (for example something like 10011010), to a certain address location on the RAM, you put that address on the address bus, all the RAM ICs receive the same address (remember parallel) and put that byte on the data bus. Now, the data bus is the one that is wired differently, each data line (D0 to D7) goes to only one RAM IC. So, each one of them receives a different digit of the data for the same address, 8 of them working together holds the whole byte, but every digit of it is stored in a different IC.
Another cracking video always like a repair on 8bit machine's 👍
Even with less editing the videos are still cool. Do what you need to, sir!
Another toast-rack saved 👍 I like the "Happy Little Diodes" channel. Posting that 16k Speccy tommorow, later than planned, but it should be with you Monday hopefully.
The 74LS157, I recognize that little bugger... It's the same type of Quad Multiplexer IC which I used in TJ's "The Ultimate Bastard" joystick... or in other words; is used in the 4 button version of a Sega Genesis/Mega Drive controller.
Great video as always! We dont need any fancy editing :)
What are those head goggles you are using there ?
You look cleverer anyway :)
Hope all goes well with your domestic doings 🤞🏻
You should be called ...Tenacious Lee
I'm always nervous about static damaging delicate electronics. Are you grounded in some way, or do you take other precautions against static?
2 Coats Lee and his furry rat 🐀
Looks baltic! Someone fetch that man a two-bar fire.
Infrared is wasted on you