The Zwölf awakens!
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The moment of truth came... without any smoke, but also without properly executing the program. The oscar showed a nice steady heartbeat and timing signals on the bus, all at the right frequencies. the state codes showed that the processor was alternately fetching instructions and executing them, as it should. There was also activity on the data bus, as well as on the address bus. perfect, but why does the LED that is hooked up to the processor's single I/O line (very much like a microcontroller) not light up at all? After some time of measuring and searching I thought that I found it. The lower address lines were connected in reverse order. Easy to fix. So I switch on the power, the power LED lights up, and the second one stays dark. I was already reaching for the power switch when it starts to blink merrily. Exactly what the program in the EEPROM should do. I guess, I should look for a smaller capacitor for that power-on reset. Here it is with both LEDs on at the moment the picture was taken.[^] It's a little hard to see on the picture because of the bright lamp. Now come a few modifications before I can safely have a board made: - Replace red LEDs (and all future displays) with blue ones. It's a High Elf, not a Dark Elf. - Add a MAX232 level shifter and we have it talking to a PC in no time over the serial port and terminal emulation. Without a UART! The same signal that now blinks the LED can be used to emulate a serial port. Of course I will need a slightly different program in the EEPROM, but I already have that ready. - Add another 8 bit register, this time set up as an output port. Then I have 24 address lines and can expand the (banked) memory up to 16 megabytes. More than enough for a little 8 bit processor. - Throw out the EEPROM and replace it with a pin compatible RAM. Now the Zwölf would not have anything to execute at startup. But that already worked on the old Elf. The processor has a 'load' mode, that can be entered after a reset and allows to load bytes into memory via DMA. The old Elf simply used it's hex keyboard and 7 segment displays as DMA devices in load mode. Today I would simply let a PIC microcontroller control the processor's mode and copy the BIOS or whatever I want it to boot from a tiny serial EPROM into memory via DMA, reset again and then switch the processor into run mode. Maybe I should still keep the door open for traditional hex keyboa
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The moment of truth came... without any smoke, but also without properly executing the program. The oscar showed a nice steady heartbeat and timing signals on the bus, all at the right frequencies. the state codes showed that the processor was alternately fetching instructions and executing them, as it should. There was also activity on the data bus, as well as on the address bus. perfect, but why does the LED that is hooked up to the processor's single I/O line (very much like a microcontroller) not light up at all? After some time of measuring and searching I thought that I found it. The lower address lines were connected in reverse order. Easy to fix. So I switch on the power, the power LED lights up, and the second one stays dark. I was already reaching for the power switch when it starts to blink merrily. Exactly what the program in the EEPROM should do. I guess, I should look for a smaller capacitor for that power-on reset. Here it is with both LEDs on at the moment the picture was taken.[^] It's a little hard to see on the picture because of the bright lamp. Now come a few modifications before I can safely have a board made: - Replace red LEDs (and all future displays) with blue ones. It's a High Elf, not a Dark Elf. - Add a MAX232 level shifter and we have it talking to a PC in no time over the serial port and terminal emulation. Without a UART! The same signal that now blinks the LED can be used to emulate a serial port. Of course I will need a slightly different program in the EEPROM, but I already have that ready. - Add another 8 bit register, this time set up as an output port. Then I have 24 address lines and can expand the (banked) memory up to 16 megabytes. More than enough for a little 8 bit processor. - Throw out the EEPROM and replace it with a pin compatible RAM. Now the Zwölf would not have anything to execute at startup. But that already worked on the old Elf. The processor has a 'load' mode, that can be entered after a reset and allows to load bytes into memory via DMA. The old Elf simply used it's hex keyboard and 7 segment displays as DMA devices in load mode. Today I would simply let a PIC microcontroller control the processor's mode and copy the BIOS or whatever I want it to boot from a tiny serial EPROM into memory via DMA, reset again and then switch the processor into run mode. Maybe I should still keep the door open for traditional hex keyboa
Cool beans, looks like you got Zwölf running like a singer sewing machine!
Monday starts Diarrhea awareness week, runs until Friday! JaxCoder.com
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Cool beans, looks like you got Zwölf running like a singer sewing machine!
Monday starts Diarrhea awareness week, runs until Friday! JaxCoder.com
Except for the slightly bigger and faster memories it's actually very close to the original Elf from 1976. Six of those little processors brought the Galileo probe to jupiter, survived in its radiation belt for years and finally crashed the probe into Jupiter, so that it does not contaminate one of the moons. Especially not the moon Europa. They did not want a dead probe with 15 kg Plutonium in its nuclear batteries to crash there.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
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Except for the slightly bigger and faster memories it's actually very close to the original Elf from 1976. Six of those little processors brought the Galileo probe to jupiter, survived in its radiation belt for years and finally crashed the probe into Jupiter, so that it does not contaminate one of the moons. Especially not the moon Europa. They did not want a dead probe with 15 kg Plutonium in its nuclear batteries to crash there.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
Yeah I read about that, pretty freaking amazing! Good luck getting a board made. Do you plan on having any extras made?
Monday starts Diarrhea awareness week, runs until Friday! JaxCoder.com
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Yeah I read about that, pretty freaking amazing! Good luck getting a board made. Do you plan on having any extras made?
Monday starts Diarrhea awareness week, runs until Friday! JaxCoder.com
Why not? But the second board is going to get more interesting. How about PS/2 ports for a mouse and a keyboard? Or an IDE port with two Compact Flash memory cards as SSDs? A MC6847 as graphics chip? A YAMAHA sound chip?
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
-
The moment of truth came... without any smoke, but also without properly executing the program. The oscar showed a nice steady heartbeat and timing signals on the bus, all at the right frequencies. the state codes showed that the processor was alternately fetching instructions and executing them, as it should. There was also activity on the data bus, as well as on the address bus. perfect, but why does the LED that is hooked up to the processor's single I/O line (very much like a microcontroller) not light up at all? After some time of measuring and searching I thought that I found it. The lower address lines were connected in reverse order. Easy to fix. So I switch on the power, the power LED lights up, and the second one stays dark. I was already reaching for the power switch when it starts to blink merrily. Exactly what the program in the EEPROM should do. I guess, I should look for a smaller capacitor for that power-on reset. Here it is with both LEDs on at the moment the picture was taken.[^] It's a little hard to see on the picture because of the bright lamp. Now come a few modifications before I can safely have a board made: - Replace red LEDs (and all future displays) with blue ones. It's a High Elf, not a Dark Elf. - Add a MAX232 level shifter and we have it talking to a PC in no time over the serial port and terminal emulation. Without a UART! The same signal that now blinks the LED can be used to emulate a serial port. Of course I will need a slightly different program in the EEPROM, but I already have that ready. - Add another 8 bit register, this time set up as an output port. Then I have 24 address lines and can expand the (banked) memory up to 16 megabytes. More than enough for a little 8 bit processor. - Throw out the EEPROM and replace it with a pin compatible RAM. Now the Zwölf would not have anything to execute at startup. But that already worked on the old Elf. The processor has a 'load' mode, that can be entered after a reset and allows to load bytes into memory via DMA. The old Elf simply used it's hex keyboard and 7 segment displays as DMA devices in load mode. Today I would simply let a PIC microcontroller control the processor's mode and copy the BIOS or whatever I want it to boot from a tiny serial EPROM into memory via DMA, reset again and then switch the processor into run mode. Maybe I should still keep the door open for traditional hex keyboa
Great! You should create kits for sale...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
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Great! You should create kits for sale...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
There already are several. ELF2K - Part 2 - Additional work and a look at PIXIE Video - STB130 - YouTube[^] Waypoint on the 1802 Membership Card Journey - YouTube[^] VIP2k - 40th Anniversary COSMAC VIP Computer Reproduction - YouTube[^] Or do you want a really mobile computer from 1980? I just love this one: Sandy Robson's 1802 Handheld | COSMAC ELF[^] And a few more, including System 00, the first of them all: Gallery | COSMAC ELF[^] Some concepts were decades ahead of its time, like using a RISC processor before RISC was invented or using low power CMOS logic when other processors were slowly cooking at 1 or 2 MHz. And look how compact all these little computers are. The Raspberry PI of its day.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
-
Why not? But the second board is going to get more interesting. How about PS/2 ports for a mouse and a keyboard? Or an IDE port with two Compact Flash memory cards as SSDs? A MC6847 as graphics chip? A YAMAHA sound chip?
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
What I meant was like this[^] guy did with the Z80.
Monday starts Diarrhea awareness week, runs until Friday! JaxCoder.com
