Search found 25 matches

by tocksin
19 Oct 2018, 13:56
Forum: Hardware and software hacking
Topic: First gigatron clone
Replies: 11
Views: 4149

Re: First gigatron clone

Boards are in! They look good on first inspection. Time to start building and testing. Thanks guys for the coupon!
IMG_2883.JPG
IMG_2883.JPG (901.57 KiB) Viewed 3093 times
by tocksin
27 Sep 2018, 17:00
Forum: Hardware and software hacking
Topic: First gigatron clone
Replies: 11
Views: 4149

Re: First gigatron clone

I made a quick cartridge example so I could make sure I didn't make any mistakes with the wiring. Turned out a lot bigger than I expected. I could probably make it smaller with surface mount chips...
2018-09-27 12_58_43-GGTcart.PrjPCB - Altium Designer (18.1.9).jpg
2018-09-27 12_58_43-GGTcart.PrjPCB - Altium Designer (18.1.9).jpg (30.46 KiB) Viewed 3223 times
by tocksin
21 Sep 2018, 14:01
Forum: Hardware and software hacking
Topic: Extending the Gigatron instruction set
Replies: 22
Views: 6662

Re: Extending the Gigatron instruction set

My new logic only requires a single extra (4x)OR chip, and I'd rather not have to add another chip. But I think I've figured out a way to have the override to select D on the lower byte without more chips. The problem is that I need an inverter and I don't have one. But I can have effectively an inv...
by tocksin
20 Sep 2018, 15:00
Forum: Hardware and software hacking
Topic: Extending the Gigatron instruction set
Replies: 22
Views: 6662

Re: Extending the Gigatron instruction set

If the diode logic is really causing that much of a slow down, you could decrease the value of the pull-up resistors. It would consume a lot more current, but that might be a easy tradeoff for speed.
by tocksin
19 Sep 2018, 13:44
Forum: Hardware and software hacking
Topic: Extending the Gigatron instruction set
Replies: 22
Views: 6662

Re: Extending the Gigatron instruction set

I like this idea. This would change the ST AC -> [X++, X++] instruction to ST AC -> [X++, D] which is much more useful. More instructions for no more chips is good!
by tocksin
18 Sep 2018, 16:05
Forum: Hardware and software hacking
Topic: All-In-One DB9
Replies: 5
Views: 1610

Re: All-In-One DB9

You could have a one cable that splits out into the multiple connectors. Or have the cables in a cable wrap, so it looks like one cable. Like this:

https://www.parts-express.com/parts-exp ... k--080-558
by tocksin
15 Sep 2018, 11:57
Forum: Hardware and software hacking
Topic: First gigatron clone
Replies: 11
Views: 4149

Re: First gigatron clone

I took the store instructions which read and write to/from RAM, and replaced them since they were useless. I kept all the others. Instead those instructions now read from the AC register and then select X as the upper byte (when 0 is not selected). The only really useful one is ST X,D, but there is ...
by tocksin
14 Sep 2018, 19:51
Forum: Hardware and software hacking
Topic: First gigatron clone
Replies: 11
Views: 4149

First gigatron clone

I don't mean to step on any toes, but I couldn't wait for a Gigatron with a built-in keyboard, so I'm making one myself. The Apple had tons of clones, so it makes sense the Gigatron should have one too. Mechanical keyboards is also a hobby of mine, so I wanted to combine the Gigatron with one. I use...
by tocksin
28 Aug 2018, 19:43
Forum: Hardware and software hacking
Topic: Audio storage of programs
Replies: 1
Views: 906

Audio storage of programs

With the creation of BASIC, I'm thinking of ways to store and load programs. I'd like to be independent of another computer. I think the best medium is something we have on hand these days - our smart phones. We could do what retrocomputers did and use audio medium to store and load programs. We hav...
by tocksin
15 Aug 2018, 20:08
Forum: Hardware and software hacking
Topic: High resolution mode?
Replies: 38
Views: 17221

Re: High resolution mode?

I wonder if a 74HCT14 would oscillate closer to 50/50 duty cycle. It's still an inverter, but has Schmitt triggered inputs. If you haven't tried it, I will get some and see if there's any improvement.