Search found 40 matches
- 24 Aug 2020, 11:37
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
The 867 seems from 1982 and still in production! Despite not reducing logic gates, replacing the four X and PC incrementers with two 867 might reduce even further chip count also in "standard gigatron" (as a "type 1" change with full hw/sw compatibility). And without external car...
- 21 Aug 2020, 18:39
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
Up only: 74xx461, 463, 590, 591, 592, 593 Up and down: 74xx469, 579, 869, 867 74HC(T)590 should be the most common one. Wonderful! So any of them can in general be used for the VGA low address! The 74xx461 as I was mentioning before is very interesting and with the potential to replace 4 ICs of X a...
- 21 Aug 2020, 06:36
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
The 163 has the preset capabilities that are not used in this case but is just 4 bit, so 2 chips will be required. There is no other option for a single chip 8-bit counter fast enough (with preset capabilities or not)?
- 20 Aug 2020, 15:23
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
You probably want to look at the 161/163 synchronous counters for doing memory addressing. The 4040 ripple counters have a 35ns propagation delay per flip-flop. The clock needs to transition through 18 stages to get to the MSB in this circuit. This is around 630ns to change from the clock edge whic...
- 18 Aug 2020, 20:32
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
VGA schema
Trying to be a bit more concrete for the VGA circuit idea I tryed to depict the circuit in kikad (have mercy please, is my first time for me drawing a circuit). screen.jpg The low address counter is using the main clock (that for now runs at around VGA dot /4), and the reset should be at 200 (=800/4...
- 18 Aug 2020, 18:52
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
I must say, that seems like a little bit of genius. I especially like the first comment saying it won't work. A brave choice of words to place under a photo of it working. II would expect it to maybe a little temperamental. Infact pretty boldish, and many considerations he put out were proved wrong...
- 18 Aug 2020, 18:29
- Forum: Hardware and software hacking
- Topic: Ye Olde Gigatron and Gigatronski
- Replies: 11
- Views: 7219
Re: Ye Olde Gigatron and Gigatronski
The Soviet chips also have a different pin spacing (2.5mm instead of 2.54mm). But I was able to (gently!) get them all into their sockets, even the larger ones. I did spend quite some time looking for Soviet replacements of the 62256 SRAM and 27C1024 EPROM, but don't believe they ever existed. The ...
- 14 Aug 2020, 12:34
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Decoupling VGA signal generation
I've found a very interesting article on generating full vga signal via a single counter and few other components: https://hackaday.io/project/9782-nes-zapper-video-synth-theremin/log/32271-vga-sync-generation With the consideration of Alastair to access the graphic memory pages on alternating clock...
- 04 Aug 2020, 21:56
- Forum: Hardware and software hacking
- Topic: microtron
- Replies: 42
- Views: 24420
Re: microtron
I have a project page on Hackaday . There's also a Git Repo with the current build tools. The ALU lookup tables are built with this Ruby script (outputs Intel HEX). It's still a work-in-progress, but I hope to have a completed version by the end of this month. I had a look at it and... I was impres...
- 04 Aug 2020, 18:54
- Forum: Hardware and software hacking
- Topic: vCPU instruction frequency
- Replies: 5
- Views: 3640
Re: vCPU instruction frequency
Just updated native instruction frequency with actual instruction code: hex frequency % cum instruction --- --------- --- --- --------------- 5d 231666880 37% 37% ora [Y,X++],out c2 43701745 7% 44% st [nn] 01 33627338 5% 49% ld [nn] 0d 26085751 4% 54% ld [Y,X] 00 24871641 4% 58% ld nn 80 19154237 3%...