Tag Archives: 8bit

Sinclair QL – modifications for EPROM

Posted on December 19, 2020 by Administrator

I have Sinclair QL, “issue 5” with 3 EPROM chips. One of the chips is riding on the other chip. And yes, it is the original solution from Sinclair engineers- they were pressed by Apple computers new product and they … Continue reading →

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Crazy ’80s – computer design with style

Posted on September 16, 2020 by Administrator

When I hear somebody talking that Apple is the pioneer in the computer design, I always want to show photo of Atari XL series: These ones are not the all, they are only ones from my personal collection. Remember, it … Continue reading →

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Repair of the Atari 2600 jr

Posted on April 18, 2020 by Administrator

I found PCB from the classic 2600 JR. It was forcefully removed from the case maybe using a hammer. The PCB is bent, some parts torn out and missing switches. PCB was cracked and several traces were broken. I repaired … Continue reading →

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Thing to know: Z80 CPU clock

Posted on April 17, 2020 by Administrator

I just only want to send notes to myself. Z80 CPU clock must be 5Vpp and pure TTL levels sometimes are too low for good and stable CPU work. Even this old CPU is very stable at 5Vpp clock, meanwhile … Continue reading →

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ZX LCD

Posted on March 26, 2020 by Administrator

After building ZX Spectrum clone in CPLD I ported hardware code to another project and this is a bit simpler, but it uses some mono LCD from old copy machine. Now I used only one CPLD, but I added an … Continue reading →

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Cartridge for Commodore 64

Posted on March 25, 2020 by Administrator

Sometimes I want to show how old 8 bit computers work for some n00bs. It is nice to load some games from tape, some from disk. But when I want to show more games, the best thing is cartridges. And … Continue reading →

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ZX Spectrum inside CPLD

Posted on March 24, 2020 by Administrator

I found an old ZX Spectrum clone made in Soviet Union in the 90’s. It was my computer, I wrote several programs on it and also, I wrote drivers for Epson printer on this hardware. This model has Soviet chip … Continue reading →

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Testing Commodore 6526/8520 copy in CPLD

Posted on March 21, 2020 by Administrator

There are quite expensive obsolete chip from various Commodore computers and peripherals- CIA/PIA MOS 6526 and a bit changed 8520 used in Amiga computers. This is a “complex” peripheral interface adapter chip for 6502 processor or 68K chipset. It is … Continue reading →

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My collection of old computer

Posted on March 1, 2020 by Administrator

For a long time, I collected a small collection of computer hardware. Here is the link to my Old Bits Collection.

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Building 8bit ATARI test ROM in easy way

Posted on May 3, 2018 by Administrator

I was experimenting with damaged Atari 800XL and I need to test it in low level. I wrote several lines in machine code and it was pain in the ass to fill data to ROM chip. After entering HEX data … Continue reading →

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