Search found 5 matches
- 06 Apr 2019, 21:40
- Forum: Hardware and software hacking
- Topic: Clock circuit check
- Replies: 3
- Views: 3730
Re: Clock circuit check
As a sanity check, measure the voltage at the power input jack. If that's good, then look at the polarity of the Zener diode D1. The zener is installed across the power rails in the opposite direction of a normal diode. If installed the wrong way it would become a short and would definitely drop the...
- 02 Apr 2019, 22:01
- Forum: Hardware and software hacking
- Topic: Another Gigatron Instruction Set Question.
- Replies: 2
- Views: 2692
Re: Another Gigatron Instruction Set Question.
Thanks for the reply and the documentation pointers. The ROM code makes much more sense once you know that store can writes to ram and a register in a single instruction.
- 01 Apr 2019, 22:51
- Forum: Hardware and software hacking
- Topic: Another Gigatron Instruction Set Question.
- Replies: 2
- Views: 2692
Another Gigatron Instruction Set Question.
Some aspects of the Gigatron remind me of the 6502, which shouldn't be a shock since they're both eight bit CPU's with three registers. One similarity is that it is possible to load X or Y with a load instruction, or to move a value from the accumulator into them. For example, I think this: ld [$17]...
- 30 Mar 2019, 00:19
- Forum: Hardware and software hacking
- Topic: Decoding Branch Instructions
- Replies: 2
- Views: 2650
Re: Decoding Branch Instructions
Thanks for the reply. Glad that it's the web page and not me.
Also thanks for the link to the control unit. Reading through the schematics is next on my agenda.
Also thanks for the link to the control unit. Reading through the schematics is next on my agenda.
- 29 Mar 2019, 21:34
- Forum: Hardware and software hacking
- Topic: Decoding Branch Instructions
- Replies: 2
- Views: 2650
Decoding Branch Instructions
First off. Nice Job on the Gigatron! I've been reading through the documentation, and I watched your YouTube video on how it worked. It was quite interesting to see how you did without microcode for instruction sequencing. To really understand it, I read the ROM assembler, and mapped the machine cod...